As I write this, most of Western Europe is in some state of lockdown. And not just Europe; to give one example, the government of Vietnam last weekend did the same to Hanoi and Ho Chi Minh City.
What is the aim here? Many point to China, Singapore and South Korea: if we can just use big data and testing to identify and contact trace every infected person, we can get new cases down to zero. That is what China has almost done: new cases are now usually imported. Unless we shut down borders and impose quarantines universally, this strategy cannot work forever. But, some argue, it buys time for a vaccine and effective treatments to be developed.
There is a contrarian view. This is that we are fighting a disease where the denominator is unknown: we literally have no idea how many people have been exposed to coronavirus. My son returned in late January from a trip to Northern Italy, complaining to me on WhatsApp about delays checking in due to “armies of Chinese families” ahead of him. Shortly after he got back, he developed fever and diarrhoea. I thought it must be a norovirus or similar bug until I saw the NEJM paper which said 5% of Chinese patients also presented with diarrhoea. Shortly afterwards my partner developed a cough and a fever. It wiped her out for a couple of days, but I discounted the idea that it could be COVID-19 – that would be much more serious, surely?
The truth is that without an antibody test – and widespread antibody testing – we have very little idea how far coronavirus has spread. It appears children and younger people can acquire the virus while being almost asymptomatic. It could be that SARS-CoV-2 could be much more widespread in the population than we think. This was supported by a Science paper which noted that “undocumented infections often experience mild, limited or no symptoms and hence go unrecognized, and, depending on their contagiousness and numbers, can expose a far greater portion of the population to virus than would otherwise occur.”
The next question is whether infection confers protection from subsequent exposure. Despite a few case reports suggesting reinfection does occur, experience from other coronaviruses suggests that protection will occur – at least for several months, if not years. And if it is shown that reinfection in exposed populations is very widespread with SARS-CoV-2 then the chances of creating an effective vaccine have dropped substantially.
Countries are racing to produce an antibody test. Hopefully we will soon have better data. My hope is that we are much further down the path of mass infection than we think. The lockdowns will inevitably weaken over time. The much-criticised ‘herd immunity’ target of 60% of the population exposed is worth achieving, while we make sure those at high risk avoid exposure. People talk about a vaccine being available in a year, but eighteen months to two years is more likely – if ever. We can’t stop economies for that length of time without substantial collateral damage to many people’s health through increased levels of poverty.
Here in the UK, it is clear some policymakers consider the lockdowns may have to continue until the early part of 2021, or later. We are in uncharted territory. But my hope is that we may be further down the path to herd immunity than the models currently suggest.