The 2020 Lockdowns

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(around 260 million people) would have contracted the disease. Of those, 2,2 million Americans would have died, including 4% to 8% of those over age 70 (Ferguson 2020). In Germany alone, the SARS-CoV-2 pandemic could have resulted in 730.000 deaths (Barbarossa 2020) with 500.000 deaths each in France, Italy, Spain and the UK.

Fortunately, the world has been spared from a freely circulating SARS-CoV-2. If humanity can change the climate, why shouldn’t we 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, at first, almost all governments considered saving hundreds of thousands lives more important than avoiding a massive economic recession. First in China, six weeks later in Italy and another a week later in most Western European countries, and later in the US and in many other countries in the world, unprecedented experiments of gigantic dimensions were started: ordering entire regions or the whole nation to lockdown. By the first week of April, 4 billion people worldwide were under some form of lockdown — more than half of the world’s population. Lockdowns in Europe were generally less strict than in China, allowing the continuation of essential services and industries and the circulation of people when justified. People were generally compliant to mandatory stay-at-home orders, even in the US. Based on location data from mobile devices, in 97,6% of US counties these orders were associated with decreased median population movement (Moreland 2020). Lockdowns were generally also well accepted. During the week of May 5–12, 2020, a survey among 2402 adults In New York City and Los Angeles found widespread support of stay-at-home orders and non-essential business closures, and a high degree of adherence to COVID-19 mitigation guidelines (Czeisler 2020). Lockdowns were also successful in slowing down the pandemic. In New York City, SARS-CoV-2 prevalence varied substantially between boroughs between 22 March and 3 May 2020 (for example, Manhattan: 11,3%; South Queens: 26,0%). These differences in prevalence correlate with antecedent reductions in commuting-style mobility between the boroughs. Prevalence was lowest in boroughs with the greatest reductions in morning movements out of and evening movements into the borough (Kissler 2020). According to one study, between 12 and 15 million individuals in Europe had been infected with SARSCoV-2 by May 4th, representing only between 3,2% and 4,0% of the population (Flaxman June 2020). Projected percentages of the total population infected ranged from a low of 0,76% in Austria to a high of 8,0% in Belgium. In South

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America, lockdowns were successful, too, although they worked best among the wealthy and less well among the less wealthy who had to choose at times between the risk of dying from COVID or dying from hunger.

Curfews

Lockdowns are effective but frighteningly costly. The spring lockdown cost most countries around 10% of their PIB with unforeseeable economic, political and also health consequences; in exchange, they can “flatten the curve” and did succeed in keeping seroprevalence rates low, somewhere between 1% and 10%. Generalised lockdowns are clearly not a viable, long-term model for the future. Might curfews be a less costly alternative, both economically and socially? In French Guiana, an French overseas départment, a combination of curfews and targeted lockdowns in June and July 2020 was sufficient to avoid saturation of hospitals. On weekdays, residents were first ordered to stay at home at 11 p.m., then at 9 p.m., later at 7 p.m., and finally at 5 p.m. On weekends, everyone had to stay at home from 1 p.m. on Saturday (Andronico 2020). Whether curfews can be successfully adapted to other areas than French Guiana, is not known. French Guiana is a young territory with a median age of 25 years and the risk of hospitalization following infection was only 30% that of France. About 20% of the population had been infected with SARS-CoV-2 by July 2020 (Andronico 2020). Following Belgium and Germany, France has just implemented now a night curfew in Paris and a few other major cities. Be prepared to see more curfews orders over the coming six months.

The “second wave”

There is no real pandemic in Africa, a never-ending wave in the Americas, and now a second wave in Europe. The worst may be yet to come (The Lancet 2020) with more people dying and every death leaving 10 more people mourning a grandparent, parent, sibling, spouse, or child (Verdery 2020). Will the SARS-CoV-2 pandemic follow the scenario of the 1918 influenza pandemic (Horton 2020) with a much worst second wave? In anticipating local epidemics, politicians should prepare for the worst, at least until spring 2021. There are important differences between the springtime “first wave” of COVID-19 epidemics in Europe and the late-summer and autumn second wave. An important feature of this second wave of infections is its widespread nature, as opposed to earlier, more localized outbreaks (e.g., northern Italy, Madrid, Spain or Mulhouse, France.) More populated and better-connected municipalities were generally affected earlier by the SARS-CoV-2 epidemic,

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and less populated municipalities at a later stage of the epidemic (de Souza 2020). Relaxation of mitigation measures and the decreased burden of diseases during the summer led to a resumption of “normal life” behaviors and a resurgence of infections. Initially, the diffusion of the virus may have appeared to have few negative effects, only to lead to deadly outbreaks weeks or months later (Thomas 2020). Public health messaging must stress that apparent lulls in disease progress are not necessarily indicators that the threat has subsided, and that areas “passed over” by past outbreaks could be impacted at any time. A second major difference in this second wave is the role played by different age groups in the spread of the virus. Understanding whether increasing incidence is predominantly occurring in specific age groups is important for identifying opportunities to prevent or reduce transmission (Oster 2020). In the French Bouches-du-Rhône department, which includes Marseille, the first signs of the second wave were detected in wastewater on July 132. Three weeks later, the first post-lockdown rise in new SARS-CoV-2 infections was seen in young adults 20 to 29 years old; and again a few weeks later, infection rates increased in older age groups. In Spain (NCOMG 2020), Switzerland (see Figure 1.4) and other European countries, the second wave looked equally triggered mostly by transmission among young adults in leisure venues such as bars, restaurants, discos or clubs during the summer of 2020. In the USA, the summer COVID-19 dynamic was comparable. During June–August 2020, SARS-CoV-2 incidence was highest in persons aged 20–29 years, who accounted for > 20% of all confirmed cases. Across the southern United States, in June 2020, increases in percentage of positive SARS-CoV-2 test results among adults aged 20–39 years preceded increases among those aged ≥ 60 years by 4–15 days (Boehmer 2020, Oster 2020). First the kids, then the parents and, finally the grandparents – with unknown outcome?

2 SARS-CoV-2 can be detected in wastewater using RT-qPCR. In one study, the total load of gene equivalents in wastewater correlated with the cumulative and the acute number of COVID-19 cases reported in the respective catchment areas [Westhaus 2020]. Note that wastewater is no route for SARS-CoV-2 transmission to humans! All replication tests were negative tests.

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Figure 1.4. Weekly positive SARS-CoV-2 tests in Switzerland by age group (August 3 through October 5).Source: SRF, So entwickeln sich die Corona-Zahlen in der Schweiz (https://www.srf.ch/news/schweiz/coronavirus-so-entwickeln-sich-die-corona-zahlen-in-derschweiz; accessed 12 October 2020).

Herd immunity: Not yet!

Herd immunity, the notion introduced to a wider public by a foolish politician, may not be on the agenda for a long time. Herd immunity, also known as indirect protection, community immunity, or community protection, refers to the protection of susceptible individuals against an infection when a sufficiently large proportion of immune individuals exist in a population (Omer 2020). As for now, not a single country is anywhere close to reaching herd immunity. Even in past hotspots like Wuhan, the prevalence of SARS-CoV-2 IgG positivity was 9,6% among 1021 people applying for a permission to resume work (the SARS‐CoV‐2 nucleic acid test needed to be negative) (Wu X 2020). A French study projected 2,8 million or 4,4% (range: 2,8–7,2) prevalence of infections in France. In Los Angeles, the prevalence of antibodies was 4,65% (Sood 2020). (And even this low number may be biased because symptomatic persons may have been more likely to participate.) A nationwide coronavirus antibody study in Spain showed that about 5% of the population had contracted the virus. These infection rates are clearly insufficient to avoid a second wave of a SARS-CoV-2 epidemic (Salje 2020). Achieving herd immunity