Coronavirus: how to stop a second wave
FT science writer Anjana Ahuja explains the science behind governments' strategies to ease lockdown restrictions while allowing economies to reopen
Produced and edited by James Sandy; motion graphics by Victor Diaconescu; additional footage from Reuters and Getty
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The world might be gearing to come out of lockdown, but the threat of coronavirus hasn't gone away. Anyone who hasn't yet had the disease is just as susceptible to catching it now as they were before, and no country in the world has yet achieved herd immunity, where so many of the population have been infected that the risk of infection to others becomes very low. And while lifesaving drugs may have hit the news recently, with one called Remdesivir being given emergency authorisation in the US, no drug has yet been shown to improve the survival chances of Covid patients.
Only a vaccine can allow us to get back to normality. And realistically, that's going to take at least until 2021. Until then, stopping the transmission of coronavirus is the only defence we have.
Some countries have seen the reproduction number, the fabled R number, fall below one. This is critical for disease control. If R is two, then 10 infected people will, on average, pass the disease on to 20 more, and the epidemic grows exponentially. If the R is 0.5, those 10 infected people will only infect another five, and the epidemic gradually declines.
The problem is the lockdowns that are keeping R below one on not seen as sustainable, both for economic and long-term health and social reasons. So how can governments free up economies while keeping Covid-19 under control? In the absence of any certainty, different countries are taking different approaches, but most are favouring the basic principle of testing, tracking, and tracing. That allows public health officials to know where the virus is and how it's spreading so it can be contained.
South Korea has used this technique since the start of the pandemic. It relies on the population using a smartphone app that can track any individual's location. If that individual then comes into close contact with someone who later tests positive, the app will alert them and they can, in turn, get tested and self-isolate.
Apps designed to track and trace are not without their problems, though. In order to work effectively they need the majority of the population to download and use them, and many have data privacy concerns. It's also unclear whether those who've been close to someone with the virus should be forced to isolate. Those living and working in busy areas, like cities, could end up bouncing from one period of isolation to another.
Another idea is to give people immunity certificates or immunity passports, which would exempt workers from lockdowns because they've already had the virus. But until we really understand the link between antibodies and immunity, the World Health Organisation has warned against countries adopting this approach. Sending people who have already had the virus back into circulation could pose an infection risk.
When it comes to relaxing restrictions some countries are trying a more nuanced approach which doesn't treat the entire population as a uniform blob. France has opted to divide the country into red and green zones, which have slightly different rules. Red zones, which include Paris, are where the virus is still circulating and the burden on intensive care units is high. So parks, for example, can reopen in green zones but not red ones.
There is also a discussion on whether there should be different rules for young and old or at-risk groups. Medically speaking, the young are the least at risk from the virus but possibly the hardest hit by lockdowns, in terms of lost education and work.
Each country will end up choosing its own distinctive path out of lockdown. Whether a government decides to reopen schools and restaurants or to allow more contact between households will depend on many things. Its capacity to track and trace, how old its population is, and its mix of urban and rural communities. There may also be cultural considerations. But for now, as we wait for a vaccine, keeping R down while society finds some kind of new normal is the only approach any nation can take.