A number of countries have managed to stem the spread of SARS-CoV-2. Island nations that moved swiftly, like New Zealand and Iceland, reported no new cases of infection yesterday.
Some observers, looking at the low number of Covid-19 deaths in places like Iceland (10) and New Zealand (20), are describing the recent restrictions on businesses and personal movement aimed at stemming the spread as an over reaction.
In an interview with The Guardian, Christian Drosten, Germany’s leading coronavirus expert, called this the prevention paradox. If those in charge successfully reduce the spread and save lives, they’re likely to be criticised for seemingly overreacting. “..for many Germans I’m the evil guy who is crippling the economy. I get death threats…” said Drosten.
The prevention paradox arises because there is no scientific control. There is no Iceland without social distancing to compare to an Iceland with social distancing, no Switzerland without social distancing to compare to a Switzerland with social distancing.
However, there are other places where lockdown came later and worked less well that offer a glimpse of how things might have turned out in places that did well at containing the spread.
New York City (8.54 million) and Switzerland (8.57 million) have similar sized populations. Both New York City (13.5%) and Switzerland (13.3%) have a similar percentage aged over 64, the age group hardest hit by the virus.
By 4 May 2020, NYC had 175,651 confirmed cases (2.1% of the population), 19,057 deaths, around 130,000 estimated active cases and an estimated 43,045 people hospitalised with Covid-19. Given NYC’s large number of remaining active and hospitalised cases it is possible deaths there could reach 30,000 if new drugs and treatments take too long to materialise.
Compared to Switzerland, NYC, with its high population density and reliance on public transport, was at a natural disadvantage when trying to stem the spread of this disease. However, given enough time, a virus like SARS-CoV-2 will eventually spread through any interconnected population if enough connections are not interrupted.
Of course this comparison isn’t perfect. The underlying health of these two populations could be different, something that could affect death rates. Hospital capacity and the ability to keep people alive is another factor. And there might be differences in how it spread, for example to more or fewer vulnerable people. It is likely more differences will come to light too, for example, genetic or immunological differences.
However, NYC offers at least some insight into what SARS-CoV-2 can do when it isn’t well contained and really starts to spread successfully, something that could potentially happen anywhere given enough time and the right conditions. In some ways, NYC, with its dense population and subway system, is the world’s accelerated spread experiment. Spread on fast forward.
Recent antibody testing suggests 20% of NYC’s population have been infected, 10 times the confirmed case percentage. If accurate, that still leaves 80% of the population uninfected.