The prevailing view has seemed to be that the virus has only reached a small fraction of the population, and that lockdown stopped it in its tracks; lifting lockdown will sooner or later result in resurgence that is just as bad as before or worse, unless we can manage to keep it down with distancing and sanitising and testing and tracing.
But there are other views, and there are certainly observations that contradict the above idea: why did Sweden’s infection rate peak and go down without a lockdown? Why has exponential growth tailed off in such a similar way across countries with a diversity of intervention levels and timings?
One suggestion has been that the virus has spread a lot further through the population than it seems; seroprevalence studies aren’t the whole story as there can be T-cell immunity and perhaps other types of immunity post-infection that we’re not detecting. It would mean a very high proportion of cases were asymptomatic. This seems legit up to a point – but I think extensive, unobserved, largely asymptomatic spread would mean that symptomatic cases would pop up all over the place seemingly unconnected to any others, and I don’t think that’s been the pattern.
Another idea is that a large proportion of the population are inherently not susceptible to the virus and won’t be infected. That doesn’t make sense to me either, because it would be much harder in that case to set off the rapid global spread that happened earlier this year.
I think it’s simply that the idea of exponential growth is wrong, as it’s based on a model in which people move around randomly interacting with others like gas molecules bumping into each other. We don’t do that, we have fixed homes and workplaces and social circles. Without hard borders anywhere, the virus will of course keep spreading, but more slowly. When it enters new susceptible communities, spread will take off exponentially again within those areas, and we’re seeing that in localised outbreaks now.
I don’t think a new wave will be as bad as the first, on a national level. I think the spread, as well as being slowed down naturally as before by limited movement of people, will be further slowed down by distancing, sanitising, masks, and some immunity from the first wave.
Reapplying lockdowns is like cracking a nut with a sledgehammer and I fear more for the collateral damage of that. We seem at times to be fixated on achieving “elimination” at a moment in time, which will be meaningless in the grand scheme of things.
The way we’re operating now – Phase 3 of easing – is pretty much what Sweden has been doing throughout. (Maybe a bit more cautious – I don’t think they’re using masks in Sweden.) It feels to me like a balanced approach that will not overwhelm healthcare. We’ve had a good summer with this approach. I hope we can hold our nerve and continue.