Epidemiology

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By Bernd Sebastian Kamps

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In December 2019, several patients from Wuhan, People’s Republic of China, developed pneumonia and respiratory failure reminiscent of the SARS epidemic in 2003 (WMHC 2019, www.SARSReference.com). In early January 2020, a new virus was grown from bronchoalveolar lavage fluid samples and found to be a betacoronavirus (Zhou 2020). Between then and the time of this writing (19 April), the virus has spread to every corner of the world. More than 2.3 million have been diagnosed and > 160,000 people have died.

In this chapter, we will discuss

  • the transmission routes of SARS-CoV-2;
  • the natural COVID-19 epidemic and Epidemic 2.0;
  • lockdown and measuring its effects;
  • the characteristics of the epidemic in selected places;
  • lockdown exit;
  • ‘COVID pass’;
  • a second epidemic wave.

Transmission

Person-to-person spread

Transmission of coronaviruses is airborne, fecal-oral or through fomites. (A fomite is any inanimate object that, when contaminated with or exposed to infectious agents such as a virus, can transfer a disease to another person, for example elevator buttons, restroom taps, etc.) (Cai 2020). It is assumed that SARS-CoV-2 is spread mainly through person-to-person contact via respiratory droplets generated by coughing and sneezing. Whether and to what extent other transmission routes are epidemiologically relevant is unclear.

Human-to-human transmission of SARS-CoV-2 was proved within weeks (Chan 2020, Rothe 2020). It is unknown if symptom severity is a proxy for infectivity. Even asymptomatic individuals can transmit the virus and a substantial proportion of secondary transmission is believed to occur prior to onset of illness (Nishiura 2020). However, in one case report, there was no evidence of transmission to 16 close contacts, among them 10 high-risk contacts, from a patient with mild illness and positive tests for up to 18 days after diagnosis (Scott 2020).

The SARS-CoV-2 virus is highly contagious, with a basic reproduction number R of around 2.5 (Chan 2020, Tang B 2020, Zhao 2020). [R indicates the average number of infections one case can generate over the course of the infectious period in a naïve, uninfected population.]

The mean incubation is around 5 days (Li 2020, Lauer 2020). The serial interval of COVID-19 – defined as the duration of time between a primary case-patient having symptom onset and a secondary case-patient having symptom onset – has been estimated to be between 5 and 7.5 days (Cereda 2020).

The issue of fomites is still a topic of public anxiety. One study (van Doremalen 2020) showed that the virus can be detectable as an aerosol (in the air) for up to three hours, up to four hours on copper, up to 24 hours on cardboard and up to two to three days on plastic and stainless steel. Hence the imperative advice for regular and thorough handwashing.

Transmissibility of SARS-CoV-2 appears not to be reduced in warm and humid conditions (Luo 2020). However, one study suggests that high temperature and high relative humidity might reduce the transmission of COVID-19 (Wang 2020). It is still unclear if and to which extent the epidemic might temporarily slow down in Europe and North America during the 2020 summer.

Nosocomial spread

Hospitals seem to be a favorable environment for the propagation of the SARS-CoV-2 virus. In some instances, hospitals might be the main COVID-19 carriers, as they are rapidly populated by infected patients, facilitating transmission to uninfected patients (Nacoti 2020). Within the first 6 weeks of the epidemic in China, 1,716 cases among health care workers were confirmed by nucleic acid testing, and at least 5 died (0.3%) (Wu 2020). One study reports that the virus was widely distributed in the air and on object surfaces in both the intensive care units and general wards, implying a potentially high infection risk for medical staff. Contamination was greater in ICUs. Virus was found on floors, computer mice, trash cans, sickbed handrails and was detected in air approximately 4 m from patients (Guo 2020). The virus has also been isolated from toilet bowl and sink samples, suggesting that viral shedding in stool could be a potential route of transmission (Young 2020, Tang 2020). However, most of these studies have evaluated only viral RNA. It remains to be seen whether this translates into infective virus.

Although nosocomial spread of the virus is well documented, appropriate hospital infection control measures can prevent nosocomial transmission of SARS-CoV-2 (Chen 2020). This was nicely demonstrated by the case of a person in her 60s who travelled to Wuhan on Dec 25, 2019, returned to Illinois on Jan 13, 2020, and transmitted SARS-CoV-2 to her husband. Although both were hospitalized in the same facility and shared hundreds (n=348) of contacts with HCWs, nobody else became infected (Ghinai 2020). However, working in a high-risk department, longer duty hours, and suboptimal hand hygiene after coming into contact with patients, were all associated with an increased risk of infection in health care workers (Ran 2020). At one time during the early epidemic in March 2020, around half of 200 cases in Sardinia were among hospital and other health care workers.

At the end of March, medical personnel represented 12% and 8% of reported Spanish and Italian infections, respectively. Whether there should be universal masking in hospitals is still being debated. The main value could be in giving health care workers the confidence to absorb and implement prevention practices (Klompas 2020).

As of 18 April, 130 doctors had died in Italy (roughly half of them family doctors), 23 in Spain and a yet unknown number in France.

Transfusion

After screening of 2,430 donations in real-time (1,656 platelet and 774 whole blood), authors from Wuhan found plasma samples positive for viral RNA from 4 asymptomatic donors (Chang 2020). It remains unclear whether detectable RNA signifies infectivity.

In a Korean study, seven asymptomatic blood donors were later identified as COVID-19 cases. None of 9 recipients of platelets or red blood cell transfusions tested positive for SARS-CoV-2 RNA (Kwon 2020). More data are needed before we can conclude that transmission through transfusion is unlikely.

Long-term care facilities

Long-term care facilities are high-risk settings for infectious respiratory diseases. In a skilled nursing facility in King County, Washington, US, 167 cases of COVID-19 were diagnosed within less than three weeks after the identification of the first case: 101 residents, 50 health care personnel and 16 visitors (McMichael 2020) (Table 1).

Among residents (median age: 83 years), the case fatality was 33.7%. Chronic underling conditions included hypertension, cardiac disease, renal disease, diabetes mellitus, obesity and pulmonary disease. The study demonstrates that once introduced in a long-term care facility, SARS-CoV-has the potential to spread rapidly and widely.

Table 1. COVID outbreak in a long-term care facility
  Residents
(N = 101)
Healthcare personnel
(N = 50)
Visitors
(N = 16)
Median age (range) 83 (51-100) 43.5 (21-79) 62.5 (52-88)
Female (%) 68.3 76 31.2
Hospitalized (%) 54.5 6.0 50.0
Died (%) 33.7 0 6.2
Chronic underlying conditions (%)      
Hypertension 67.3 8.0 12.5
Cardiac disease 60.4 8.0 18.8
Renal disease 40.6 0 12.5
Diabetes mellitus 31.7 10.0 6.2
Obesity 30.7 6.0 18.8
Pulmonary disease 31.7 4.0 12.5

 

Cruise ships and aircraft carriers

Cruise ships carry a large number of people in confined spaces. On 3 February 2020, 10 cases of COVID-19 were reported on the Diamond Princess cruise ship. Within 24 hours, ill passengers were isolated and removed from the ship and the rest of the passengers quarantined on board. Over time, more than 700 of 3,700 passengers and crew tested positive (~20%). One study suggested that without any interventions 2,920 individuals out of the 3,700 (79%) would have been infected (Rocklov 2020). The study also showed that an early evacuation of all passengers on 3 February would have been associated with only 76 infected. Today, all cruise ships are idle in ports around the world and face an uncertain future. Shipping village-loads of people from one place to another may not be a viable business model for years to come.

Large navy vessels seem equally prone to large outbreaks. During an epidemic on the aircraft carrier USS Theodore Roosevelt in late March, around 600 sailors out of a crew of 4,800 were infected with SARS-CoV-2 (see also the March 30 entry of the Timeline); around 60% remained asymptomatic. One active duty sailor has died as of 17 April (USNI News). On the French aircraft carrier Charles-de-Gaulle, a massive epidemic was confirmed on 17 April. Among the 1,760 sailors, 1,046 (59%) were positive for SARS-CoV-2, 500 (28%) presented symptoms, 24 (1.3%) sailors were hospitalized, 8 on oxygen therapy and one in intensive care.

Transmission hotspots during lockdown

It seems that under strict lockdown conditions (with the population confined to their homes and allowed only to go to work and do essential shopping), transmission continues mainly in places where people are crowded and/or working closely together:

  • Hospitals
  • Long-term care facilities
  • Prisons
  • Aircraft carriers and other military vessels

The pandemic

Natural Pandemic

The COVID-19 epidemic started in Wuhan, in Hubei province, China, and spread within 30 days from Hubei to the rest of mainland China, to neighboring countries (in particular, South Korea, Hong Kong and Singapore) and west to Iran, Europe and the American continent. The first huge outbreaks occurred in regions with cold winters (Wuhan, Iran, Northern Italy, Alsace region in France).

A hundred or even 50 years ago, the COVID-19 pandemic would have followed its natural course. With a mortality rate of around 0.5%, COVID-19 would have resulted globally in 7.0 billion infections and 40 million deaths during the first year (Patrick 2020). The peak in mortality (daily deaths) would have been observed approximately 3 months after the beginning of local epidemics. One model predicted that 80% of the US population (around 260 million people) would have contracted the disease. Of those, 2.2 million would have died, including 4% to 8% of Americans over age 70 (Ferguson 2020).

Some politicians seriously considered such a Pandemic 1.0 plot, speculating on the advantages of “letting-the-virus-loose”:

  • The country would avoid the dramatic economic downturn that seems unavoidable in countries and states which opted for strict containment measures (Italy, Spain, France, California, New York, to name a few).
  • After three months, 70% of the population would be immunized against further outbreaks (through infection with SARS-CoV-2) and would be able to look ahead to the next winter season with an even temper. (How long would such acquired immunity last? Maybe only a few years. See the Immunology chapter, page 89).

In mid-March 2020, the prime minister of an ex-EU country thus introduced the notion of ‘herd immunity’ as a solution to the epidemic his nation was about to face. The shock treatment: accepting that a large majority of the population would contract the virus, thus developing a collective immunity and avoiding coronavirus epidemics in the immediate future. The figures were dire. With a little over 66 million inhabitants, some 40 million people would have been infected, 4 to 6 million would have become seriously ill, and 2 million would have required intensive care. Around 400,000 Britons would have died. The prime minister forecast: “Many more families are going to lose loved ones before their time.”

Pandemic 2.0: Lockdown

Fortunately, for now, the world has been saved from a freely circulating SARS-CoV-2. After all, humanity can change climate, so why shouldn’t it be able to change the course of a pandemic? Although economists warned that unemployment could surpass the levels reached during the Great Depression in the 1930s, almost all governments rated saving hundreds of thousands lives higher than avoiding a massive economic recession. First in China, six weeks later in Italy and still another week later in most Western European countries, an unprecedented experiment of gigantic dimensions was started: ordering entire nations to lockdown. In Italy and Spain, people were ordered to stay home, except for “essential activities” (purchasing food, medicine and other necessities) and going to hospital or work. Italians were told to stay at home even on the popular Pasquetta day, Little Easter, where people usually flock to the countryside to enjoy a picnic with family and friends.  Italians were not even allowed to move from one village to another.

Lockdown results

The result of lockdown measures can be measured by the number of

  • SARS-CoV-2-infected people
  • Hospital admissions
  • Patients treated in intensive care units (ICU)
  • Deaths

Number of infections

The daily communication of newly diagnosed SARS-CoV-2-infected people has become a ritual in most countries. These figures are indeed an indicator for the evolution of a national epidemic and the effects of lockdown measures.

However, these data do not reflect the true number of infections. To know the true number, the entire population would need to be tested which is of course impractical. Best estimates can only be made by mathematical modelling. Surprisingly, the first accurate models of the European epidemic revealed that reported COVID-19 cases represent only a fraction of those truly infected. A model based on observed deaths in 11 European countries suggested that true infections were much higher than reported cases (Flaxman 2020). According to the model, as of 28 March, in Italy and Spain, 5.9 million and 7 million people could have been SARS-CoV-2-infected, respectively (Table 2). Germany, Austria, Denmark and Norway would have the lowest attack rates (proportion of the population infected). If these assumptions are validated, the true number of cases would outnumber the reported cases on March 28 (Italy: 92,472; Spain: 73,235; France: 37,575) by up to two orders of magnitude.

[The data provided by Flaxman et al. immediately invite one to do some kitchen epidemiology. First: if on 28 March the number of infected people in Italy was around 6 million (with a credible interval of 2 to 15 million) and if we assume that 18 days later the total number of deaths in Italy was around 30,000 (the official figure reported on 15 April was 21,645 deaths), the mortality of COVID-19 infection in Italy could be in the range of 0.5% (0.19%-1.6%).

Second: if at the end of March, around 60% of all deaths in Italy were reported from Lombardy, 60% of the 6 million projected Italian SARS-CoV-2 infections – 3.6 million – would have occurred in a region with a population of 10 million. Moreover, 20% of all deaths in Italy were reported from the province of Bergamo alone which has a population of one 1.1 million. Seroprevalence studies will sort out these figures soon.]

 

Table 2. Estimates of total population infected as of 28 March 2020
Country
Deaths on 28 March
% of population
infected*
Population infected*
Austria
68
1.1% (0.36%-3.1%) 96,800
(31,680-272,800)
Belgium
353
3.7% (1.3%-9.7%) 425,500
(149,500-1,115,500)
Denmark
65
1.1% (0.40%-3.1%) 63,800
(23,200-179,800)
France
2,314
3.0% (1.1%-7.4%) 2,010,000
(737,000-4,958,000)
Germany
433
0.2% (0.28%-1.8%) 166,000
(232,400-1,494,000)
Italy
10,023
9.8% (3.2%-26%) 5,919,200
(1,932,800-15,704,000)
Norway
23
0.41% (0.09%-1.2%) 21,600
(4,860-64,800 )
Spain
5,982
15% (3.7%-41%) 7,035,000
(1,735,300-19,229,000)
Sweden
105
3.1% (0.85%-8.4%) 316,200
(86,700-856,800)
Switzerland
264
3.2% (1.3%-7.6%) 275,200
(111,800-653,600)
UK
1,019
2.7% (1.2%-5.4%) 1,798,200
(799,200-3,596,400)
*mean (95% credible interval)

Data source: Flaxman S et al. (Imperial College COVID-19 Response Team). Report 13: Estimating the number of infections and the impact of non-pharmaceutical interventions on COVID-19 in 11 European countries. 30 March 2020. DOI: https://doi.org/10.25561/77731

Admissions into intensive care units

A reliable indicator of the epidemic trend is the number of people treated in intensive care units. In France, the number of new hospital ICU admissions peaked on 1 April (Figure 1), while the daily variation in people treated in ICU (the balance between ICU entries and exits; Figure 2) started being negative one week later.

 

Figure 1. Daily number of new hospital ICU admissions for COVID-19 (y-axis: Nouvelles admissions en réanimation).
Source: Pandémie de Covid-19 en France, Wikipedia.

 

Figure 2. Daily variation in the number of people in ICU for COVID-19 (y-axis: Variation des cas en réanimation).
Source: Pandémie de Covid-19 en France, Wikipedia.

Deaths

Asymptomatic infections go unnoticed. Even mild to moderate symptoms may go unnoticed. Deaths do not. Consequently, deaths reflect the reality of the COVID-19 epidemic better than the number of SARS-CoV-2-infected people. Figures 3 and 4 show the number of deaths in Italy and Spain from 4 March through 19 April.

However, these numbers are incomplete and will soon be corrected upwards. (By 10%, 30%, 50% or more? Nobody knows yet.) In Italy, especially in the most hit Northern regions, a certain number of people died at home and did not appear in the official statistics. In Spain, many municipalities noted an excess mortality not reflected in the national figures. In France, as in other countries, deaths from long-term care facilities were initially not included.

Figure 3 shows that the number of daily deaths decreases about three weeks after the implementation of lockdown measures (Italy: 8/10 March; Spain: 14 March).

 

Figure 3. Coronavirus deaths in Italy and Spain from 4 March through 19 April. Source: worldometers.info, Johns Hopkins CSSE

Countries and continents

On 23 January, China ordered the first massive lockdown in history. European countries followed 6 weeks later. Astonishingly, almost no European country was really prepared for the COVID-19 epidemic although everyone could observe the events in China for more than a month. When European countries finally ordered lockdown measures, these were not as strict and swiftly imposed as in China. In some countries, lockdown was powered up over several days (Italy), while in other countries, extended subway systems continued to work and people were joyfully jogging on the streets in large numbers (Paris, France). From the very beginning, it was therefore clear that the European epidemic would need a few days or weeks more than in China to see infection and death figures decline. The following paragraphs summarize distinctive features of some local epidemics.

China

The nationwide spread to all provinces in January 2020 was favored by travelers departing from Wuhan before the Chinese Spring Festival (Zhong 2020).

Starting on 23 January, China imposed a lockdown of the population of Wuhan and later of the entire Hubei province. This astonishing first in human history achieved what even specialists didn’t dare dream: curbing an epidemic caused by a highly contagious virus (Lau 2020). This recipe of stringent confinement of people in high-risk areas, is now being re-combined by nations around the world, everyone adding some more or some less efficient ingredients.

Figure 6 proved as early as four weeks after the Wuhan lockdown that strict containment measures are capable of curbing a SARS-CoV-2 epidemic. The figure presents the Chinese COVID-19 epidemic curves of laboratory-confirmed cases, by symptom onset (blue) and – separately – by date of report (orange). The data were compiled on 20 February 2020, four weeks after the beginning of the containment measures which included a lockdown on nearly 60 million people in Hubei province as well as travel restrictions for hundreds of millions of Chinese citizens. The blue columns show that (1) the epidemic rapidly grew from 10-22 January, (2) reported cases (by date of onset) peaked and plateaued between 23 January and 28 January and (3) steadily declined thereafter (apart from a spike reported on 1 February). Based on these data, we could expect a decline in reported cases around three weeks after the implementation of strict containment measures.

 

Figure 6. The Chinese outbreak in January/February 2020. Epidemic curves by symptom onset and date of report on 20 February 2020 for laboratory confirmed COVID-19 cases for all of China. Modified from Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19). 16-24 February 2020. https://www.who.int/publications-detail/report-of-the-who-china-joint-mission-on-coronavirus-disease-2019-(covid-19)

 

Three months after the beginning of the epidemic, Chinese authorities started lifting travel restrictions, slowly restoring life to normal even in the most hard-hit provinces.

In a study on cases reported through 11 February, among 44,672 confirmed cases, most were aged 30-79 years (86.6%), diagnosed in Hubei (74.7%), and considered mild (80.9%) (Wu 2020). A total of 1,023 deaths occurred among confirmed cases for an overall case-fatality rate of 2.3%.

Models have estimated how quarantine and movement restrictions determined the outcome of the first Chinese epidemic. According to one model, without the Wuhan travel ban, there would have been 744,000 cases by February 19, day 50 of the epidemic (Tian 2020). With the Wuhan travel ban alone, the number of cases would have decreased to 202,000.

Lombardy and Italy

Italy was the first European country struck by the pandemic. Complete genome analysis of SARS-CoV-2 isolates suggests that the virus was introduced on multiple occasions (Giovanetti 2020). Although the first local case was diagnosed only on 20 January, the force of the outbreak also suggests that the virus had been circulating for weeks, possibly as early as 1 January  (Cereda 2020). People from Milan remember discussing unusual frequent occurrence of pneumonia as early as mid-January (Dario Barone, personal communication).

It is as yet unclear why the epidemic has taken such a dramatic turn in the northern part of Italy, especially in Lombardy, while other areas, especially the southern provinces, are relative spared. One super-spreader event may have been the Champions League soccer match between Atalanta (Bergamo and Valencia) on 19 February at the San Siro stadium in Milan. Forty-four thousand fans from Italy and Spain witnessed the 4-to-1 win of the Italian team. The mass transport from Bergamo to Milan and back, hours of shouting as well as the following festivities in innumerable bars have been considered by some observers as a coronavirus ‘biological bomb’. Support for this assumption comes from a recent study that visualized speech-generated oral fluid droplets with laser light scattering (Anfinrud 2020). The study found that aerosols and droplets increased with the loudness of speech. Loud and persistent shouting as would be usual during a 4-to-1 qualification for the Champions League quarterfinal can be assumed to produce the same number of droplets produced by coughing (Chao 2020).

How could the beginning of such an important epidemic be missed? The signs on the wall were there, but deciphering them was not straightforward. During the yearly flu season, COVID-19 deaths in elderly people could easily be interpreted as flu deaths. On the other end of the age spectrum, among the most active social age group – young people crowded in bars, restaurants and discos –, the rapidly SARS-CoV-2 virus would not have caused life-threatening symptoms. Before exploding, the epidemic had time (at least one month) to grow.

Spain

Spain is currently the European country with the highest number of reported and projected cases (Flaxman 2020). The region hardest hit by the epidemic is the Community of Madrid, accumulating 28% of the confirmed cases as of mid-April.

Fortunately, the Mobile World Congress in Barcelona, the world’s largest technology congress scheduled for 24-27 February, was canceled two weeks before although health authorities insisted that there was no risk. The decision was made after some of the largest technology companies (among others LG, Facebook, Sony and Vodafone) suspended their participation for fear of contagion on a large scale from those attending. This was the first blow to the Spanish tourist industry.

On March 14, the Spanish Government decreed a “state of alarm” for fifteen days, extending it later 26 April. It is now extended to May 9, although children under 12 will be able to “circulate” as of 27 April. Free movement of citizens is limited to acquisition of food and medications or going to medical centers or the workplace (as of 20 April, approx. 20% of the workforce is going to work). Masks and gloves are now given to anyone entering the metro, and will be reimbursed by the health authorities from 22 April.

France

The epidemic in France demonstrated the importance of the single most important health care figure in the COVID-19 epidemic: the number of beds available in intensive care units, equipped with respirators and fully operated by specialist staff. The first national outbreak was in the Eastern region of Mulhouse, Alsace, near the Swiss and German border, where a super-spreader event disseminated SARS-CoV-2 among the attendants of a religious meeting from 17 to 24 February. Three weeks later, patients started filling local hospitals, swiftly outstretching the capacities. Patients in serious conditions were flown out across the borders to Germany, Switzerland and Luxembourg. Then, on the weekend of 21 March, virtually from one day to another, patients were pouring into the hospitals of the Greater Paris Region where the number of available intensive care unit beds had been increased from 1,400 to 2,000 during the preceding week. At the height of the epidemic, more than 500 patients were evacuated from epidemic hotspots like Alsace and the Greater Paris area to regions with fewer COVID-19 cases. Specially adapted TGV high-speed trains and aircraft were employed, transporting patients as far away as Brittany and the Bordeaux area in the South-West, 600 km from Paris and 1000 km from Mulhouse. The French management of ICU beds was a huge logistical success.

UK

In the UK (as in some other places like Brazil and the US), clumsy political maneuvering and/or denial of the COVID-19 reality delayed the start of effective lockdown measures by a week or more. With the epidemic doubling in size about every 7 days (Li 2020), around 50% and 75% of all deaths might have been prevented with lockdown or social distancing ordered one or two weeks earlier, respectively. Preliminary data from Ireland and the United Kingdom seem to confirm this assumption. History will remember.

Germany’s low fatality rate

German’s fatality rate seems to be lower than in other countries. As of 11 April, the country reported 2,736 deaths for 122,171 cases (case fatality ration [CFR]: 1.9%). This is in stark contrast with Italy (18,849 deaths, 147,577 cases; CFR: 12.8%), Spain (13,197 deaths, 124,869 cases; CFR: 10.6) and the UK (8,958 deaths, 73,758 cases; CFR: 12.1%). It is assumed that the main reason for this difference is simply testing. While other countries were conducting a limited number of tests of older patients with severe cases of the virus, Germany was doing many more tests that included milder cases in younger people (Stafford 2020). The more people with no or mild symptoms you test, the lower the fatality rate. Reliable PCR methods have been reported by the end of January (Corman 2020).

Furthermore, in Germany’s public health system, SARS-CoV-2 testing is not restricted to a central laboratory as in many other nations but can be conducted at quality-controlled laboratories throughout the country. Within a few weeks, overall capacity reached half a million PCR tests a week. The same low fatality rate is seen in South Korea, another country with high testing rates.

As lockdown measures were less strict in Germany – people were told to stay at home but could move more freely than in Italy and Spain – the coming weeks will show the efficacy of this approach. Another important reason for the low mortality in Germany is the age distribution. During the first weeks of the epidemic, most people became infected during carnival sessions or ski holidays. The majority were younger than 50 years of age. Mortality in this age group is markedly lower than in older people.

North America

Like in Iran, where the regime covered up news of the coronavirus for three days to avoid impacting turnout at parliamentary elections on 21 February, domestic politics (i.e., the fear that economic disruption could harm re-election chances; see the British Medical Journal, 6 March 2020) influenced the epidemic response in the US. As of this writing (19 April), more than 700,000 cases and 40,000 deaths had been reported, almost half being from New York and New Jersey. The total number of deaths of the first COVID-19 wave might reach 60,000, at least half of which could have been prevented (see the UK entry, page 61). Because of an unprecedented vacuum in leadership, the US is now the epicenter of the COVID-19 epidemic.

Africa and South America

New cases are reported from around the world, but the figures are still comparatively low in Africa and South America. One study estimated the risk of transmission of the SARS-CoV-2 through human passenger air flight from four major cities of China (Wuhan, Beijing, Shanghai and Guangzhou) (Haider 2020). From 1-31 January, 388,287 passengers were destined for 1,297 airports in 168 countries or territories across the world. In January, the risk of transmission of the virus to Africa and South America seemed to be low.

On 19 April, Africa, South Africa, Egypt, Algeria and Morocco reported between 2,500 and 3,000 cases each. Algeria had the highest number of deaths (367), many of which can be traced back to citizens living or coming back from France. Such high numbers suggest that the number of infected people in Algeria could be substantially higher than the 2,500 cases officially reported.

In South America, Brazil is on track for a major epidemic fostered by bad governance. Ecuador, a country of 17 million, has the highest death toll relative to the size of its population.

Australia and New Zealand

In Australia, the total number of new cases grew exponentially after the confirmation of the first case on 25 January, levelled out around 22 March, and started falling at the beginning of April. As of 19 April, 6,606 cases had been reported, almost 50% of which from New South Wales.

New Zealand reported the first COVID-19 case on 28 February. On 26 March, the government implemented a nationwide lockdown where citizens could only leave their homes for activities such as accessing essential services. Close contact was only allowed with persons from the same household. With a population of 5 million, the country had 1,431 cases on 19 April. Twelve people died.

Lockdown exit

Over the coming weeks, countries who ordered lockdown will have to put in place a balanced lockdown exit – normalizing and restoring societal activities – while at the same time minimizing the risk of setting off a second cataclysmic wave of contagion.  (Normile 2020). The International Monetary Fund (IMF) forecast a contraction of 3% of the planet’s GDP in 2020. In a recession like no other in peacetime for nearly a century, the countries of the euro zone, the United States and the United Kingdom might see a contraction in activity of between 5.9% and 7.5%. Economically, protracted lockdown is unsustainable. What can be done once – the month-long isolation of the entire population – can probably not be repeated.

Countries will have to decide which activities to open in which order, fix a timetable, consider if some regions shall exit lockdown earlier than others and decide which activities would be shut down for 6 months or more, possibly until the general availability of a vaccine:

  1. Minimize transmission
  • All mass gatherings will probably have to be banned, including sport events, festivals and the reopening of cinemas, discos and bars. To be effective, some countries may extend some of these bans until a vaccine is available to all.
  • Postpone partly the opening of universities courses where teaching can be organized as online education.
  • Wearing face masks in public (Anfinrud 2020).
  1. Maximize economic activity (while guaranteeing social distancing)
  • Young adults need to be able to return to work, schools need to open as soon as possible to take care of young children.
  • Small shops will open first; other shops will follow.
  • Hotels and restaurants will open at a still later stage.

 

Austria was the first European country to relax lockdown measures.  On 14 April, it opened up car and bicycle workshops, car washes, shops for building materials, iron and wood, DIY and garden centers (regardless of size) as well as smaller dealers with a customer area under 400 square meters. These shops had to ensure that there was only one customer per 20 square meters. In Vienna alone, 4,600 shops were allowed to open. Opening times were limited to 7:40 a.m. to 7 p.m.  The roadmap for the following weeks and months considered the following scheme:

  • 1 May: All stores, shopping malls and hairdressers reopen.
  • 15 May: Possible opening of services such as restaurants and hotels.
  • 15 May or later: Possible re-opening of schools.
  • July: Possible – but improbable – organization of events of all sorts (sports, music, theater, cinema etc.).

From Monday, 20 April, Germany will re-open small shops with a retail space of under 800 square meters, on the condition that hygiene and social distancing measures are in place. Larger car dealerships, bike shops and book shops can also reopen.

Schools will re-open on 4 May, giving priority to students that have to take exams. Mass gatherings will remain banned throughout spring and summer. No decision has been announced as to when and whether lift restrictions on restaurants and bars.

“COVID Pass”

In countries that are currently experiencing huge COVID-19 outbreaks, tens of thousands of people will die. Those who survive severe or less severe illness, with or without hospitalization, will have developed antibodies against the SARS-CoV-2 virus (Zhang 2020, Okba 2020). Even more people, those who were infected but developed no symptoms, will have antibodies, too. All in all, millions of people in Italy, Spain and France will be thus have SARS-CoV-2 antibodies.

In South Korea and elsewhere more than 100 people who had recovered from COVID-19 were retested positive (Ye 2020) and there was concern that patients who recover from COVID-19 may be at risk of reinfection. However, there was no indication that they were contagious. The most likely explanation is that the ‘infection had been reactivated’ in the patients or that the tests picked up non-infective RNA of the virus. Very preliminary data from an animal study (n=2) suggest that that immunity acquired following primary infection may protect upon subsequent exposure to the virus. Infection of rhesus macaques with SARS-CoV-2 and re-infection after recovery showed that there was no viral replication in nasopharyngeal or anal swabs, nor any other any signs of COVID-19 disease recurrence (Bao 2020).

In mid-April 2020, we still don’t know if antibodies protect against a second infection. There is no reason to believe why they would not and most researchers strongly think they do, but further studies are needed to support the inference from our general knowledge of coronavirus infection that neutralizing antibodies are likely to be protective. Once people have recovered from SARS-CoV-2 infection, it is therefore likely that they are not vulnerable to secondary infection.

There has been speculation about the introduction of a SARS-CoV-2 antibody passport, or COVID Pass. People with neutralizing antibodies – assumed to be protected from COVID-19 infection, symptomatic and asymptomatic, and therefore unable to transmit the virus – would be allowed to freely move around. However, not only it is too early for issuing such passe-partout (see the previous paragraph), but it would also present a huge logistical challenge: Would the pass need to come in the form of a costly national identity card? How would citizens be controlled? After how many months and years would the card be revoked if antibody levels are shown to wane with time (see chapter Immunology, page 89)? For the time being, a positive SARS-CoV-2 serological status might be used in health care settings to determine who should be in close contact to confirmed or suspected COVID-19 patients.

The second wave

The dilemma faced by lockdowned countries is to restart and maximize economic activity while, at the same time, minimizing the number of new SARS-CoV-2 infections and the risk of setting off a second cataclysmic wave of contagion.

In the immediate future, there will be no return to “life before COVID-19”. The above-mentioned study by Ferguson (Ferguson 2020) predicts that after lifting strict “Stay at home” measures (extreme social distancing measures and home quarantines), the epidemic would simply bounce back (Figure 7)!

So what will our future look like? A pendulum existence of three months “Stay at home” interspersed with a few months of “Go out again”? We have good reason to believe that this is economically not viable. Unless a miraculous drug or vaccine is/are developed and produced quickly in sufficient quantities, the people of the world will have to invent intermediate measures. Mitigation strategies focusing on shielding the elderly (60% reduction in social contacts) and slowing but not interrupting transmission (40% reduction) will certainly reduce the disease and death burden by half, but would still result in 20 million deaths in 2020 (Patrick 2020). For a long time we might all wear face masks when leaving our homes and rely on intensive contact tracing and isolation of cases once the lockdown is lifted (Hellewell 2020). Fear for the second wave of the epidemic might be with us for years.

 

Figure 7. Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand (Source: Ferguson 2020).

 

Fortunately, people have the ability to learn. In any second wave of the COVID-19 epidemic, there will be no mass gatherings, no 2020 UEFA European Football Championship and no 2020 Summer Olympics in Tokyo. Discos, pubs and all other places which weeks ago brought people into close contact would be closed until further notice. In daily life, everyone would take action when experiencing fever and cough and suggesting action when witnessing it. There will be testing on a massive scale with extensive contact tracing and ensuing quarantine measures (Nussbaumer-Streit 2020).

Science

Coronaviruses have come a long way (Weiss 2020) and will stay with us for a long time. Questions abound: When will air travel resume? Will we be able to move from one country to another soon? When can we plan our next vacation and return to beaches and nightlife? Will we wear face masks for years? For how long will we live in a closed world?

The French have a precise formula to express unwillingness for living in a world we don’t recognize: “Un monde de con!” Fortunately, we will walk out of this monde de con thanks to a scientific community which is vaster, stronger and faster than at any time in history. (Should politicians who are skeptical of science be ousted out of office? Yes, please, it might be time now!) Today, we don’t know how long, how intense and how deadly the epidemic will be. We are walking on moving ground, and in the coming weeks and months, we will need to be flexible and inventive, finding solutions nobody would have imagined just months ago. Sure enough, though, science will lead the way out. If we leapt three years into the future and read the story of COVID-19, we would be excited.

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