During a Covid surge, what proportion of the population is exposed to an infective dose of the virus, which they either fight off with no or minimal symptoms or are infected by? This is one of the most important questions scientists need to answer.
It’s closely related to the question of whether lockdowns work. If lockdowns work then, as per SAGE and Imperial orthodoxy, the restrictions successfully prevent the virus from reaching most people, who remain unexposed and susceptible – and hence in need of vaccination to protect them when the protective restrictions are lifted. If lockdowns don’t work, however, then they don’t prevent the virus spreading, and thus the majority of people will be exposed to it as it spreads around unimpeded by ineffectual restrictions.
Another related question is: What proportion of exposed people are infected? Using ONS data we can estimate that around 10-15% of the country tested positive for SARS-CoV-2 over the autumn and winter. How many were exposed to the virus to produce this number of infections? Was it, say, 10-20%, with half to all of them catching the virus? Or was it more like 80-90%, with around 10% being infected? It’s a question that makes all the difference in our understanding of the virus and how to respond to it.
If almost all are exposed during a surge, and relatively few of them are infected, then a number of things follow. First, most people have enough immunity to fight off the virus when exposed to it, and only a small minority become infected. Second, the surge ends when enough of that small minority who are particularly susceptible to this virus or variant acquire immunity through infection, i.e., when herd immunity is reached. Third, there won’t be another surge or wave until there is a new virus or variant which evades enough of the existing population immunity to require herd immunity to be topped up via a further spread of infections.
If, on the other hand, very few are exposed during a surge, and most of them are infected, none of these things is true. It means: Most people have little immunity and are highly susceptible. A surge which infects 10-20% of the population has exposed not much more than that. The surge does not end because of herd immunity but because of restrictions. And there will be another surge as soon as restrictions are eased or behaviour changes and the unexposed begin to be exposed again. SAGE orthodoxy, in other words.
The evidence, however, is strongly supportive of the first position – ubiquitous exposure – not the second, limited exposure.
What SAGE Gets Wrong: The Evidence that Almost Everyone is Exposed During a Surge and Most Are ImmuneRead More