The author of the Oxford model defends her view that the virus has passed through the UK’s population.
“I think that the epidemic has largely come and is on its way out in this country so I think it [Infection Fatality Rate] would be definitely less than 1 in 1000 and probably closer to 1 in 10,000.” That would be somewhere between 0.1% and 0.01%.
It’s the biggest question in the world right now: is Covid-19 a deadly disease that only a small fraction of our populations have so far been exposed to? Or is it a much milder pandemic that a large percentage of people have already encountered and is already on its way out?
If Professor Neil Ferguson of Imperial College is the figurehead for the first opinion, then Sunetra Gupta, Professor of Theoretical Epidemiology at the University of Oxford, is the representative of the second. Her group at Oxford produced a rival model to Ferguson’s back in March which speculated that as much as 50% of the population may already have been infected and the true Infection Fatality Rate may be as low as 0.1%.
As she sees it, the antibody studies, although useful, do not indicate the true level of exposure or level of immunity. First, many of the antibody tests are “extremely unreliable” and rely on hard-to-achieve representative groups. But more important, many people who have been exposed to the virus will have other kinds of immunity that don’t show up on antibody tests — either for genetic reasons or the result of pre-existing immunities to related coronaviruses such as the common cold.
The implications of this are profound – it means that when we hear results from antibody tests (such as a forthcoming official UK Government study) the percentage who test positive for antibodies is not necessarily equal to the percentage who have immunity or resistance to the virus. The true number could be much higher.
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Asked what her updated estimate for the Infection Fatality Rate is, Professor Gupta says, “I think that the epidemic has largely come and is on its way out in this country so I think it would be definitely less than 1 in 1000 and probably closer to 1 in 10,000.” That would be somewhere between 0.1% and 0.01%.
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Professor Gupta also remains openly critical of the Government lockdown policy:
“The Government’s defence is that this [the Imperial College model] was a plausible worst case scenario. I agree it was a plausible — or at least a possible — worst case scenario. The question is, should we act on a possible worst case scenario, given the costs of lockdown? It seems to me that given that the costs of lockdown are mounting, that case is becoming more and more fragile.”
She recommends “a more rapid exit from lockdown based more on certain heuristics, like who is dying and what is happening to the death rates”. She does not believe that the R rate is a useful tool in making decisions about government policies, as an R rate is “principally dependent on how many people are immune” and we don’t have that information.
She believes that deaths are the only reliable measure, and that the number of cases should not even be presented as it is so reliant on the amount of testing being done.
She explains the flare-ups in places like New York, where the IFR seems to have been higher than 0.1%, through a combination of circumstances leading to unusually bad outbreaks, including the infection load and the layout of the population:
“When you have pockets of vulnerable people it might rip through those pockets in a way that it wouldn’t if the vulnerable people were more scattered within the general population.”
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