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I was preparing a rebuttal Adam, when I saw you'd posted a response from @BallouxFrancois at the end of your thread that rebuts nearly all of the points you've made. As he says, surveys that measure the prevalence of IgG antibodies (which you refer to) are an unreliable way of https://twitter.com/AdamRutherford/status/1282438464131170304
gauging the percentage of a population that has been exposed to SARS-CoV-2. Seroprevalence surveys are unlikely to detect IgG antibodies for asymptomatic or mild infections.
For instance, a Spanish seroprevalence survey found that 2.5% of asymptomatic patients tested positive
For instance, a Spanish seroprevalence survey found that 2.5% of asymptomatic patients tested positive
for IgG antibodies in a point-of-care test and 2% in an immunoassay; for symptomatic patients, the figure was 16.9% for both tests. See Table 2 here. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2820%2931483-5/fulltext
This and other similar findings are important because if many more people have been infected than seroprevalence surveys indicate that means the infection fatality rate is far lower than originally indicated.
The @WHO initially estimated it at 3.4%; @neilfergie and team
The @WHO initially estimated it at 3.4%; @neilfergie and team
estimated it at 0.9% and built that assumption into their modelling; the @CDCgov's best estimate was 0.26%, and it will likely continue to fall (although the @CDCgov did raise its estimate on July 10th).
As Dr John Lee, a former Professor of Pathology, wrote recently in the
As Dr John Lee, a former Professor of Pathology, wrote recently in the
@spectator: "It could yet settle closer to 0.1 per cent – similar to seasonal flu – once we get a better understanding of milder, undetected cases and how many deaths it actually caused (rather than deaths where the virus was present)." https://www.spectator.co.uk/article/how-strong-was-the-scientific-advice-behind-lockdown
To properly assess the extent of immunity in any given population, and the continuing threat posed by the virus, we need to take into account T cell immunity mediated by exposure to other coronaviruses, as @BallouxFrancois says.
According to a paper in Cell, ~70% of recovering COVID-19 patients studied had CD8+ T cells and 100% had CD4+ T cells. In addition, the researchers detected SARS-CoV-2-reactive CD4+ T cells in ∼40%–60% of unexposed individuals, suggesting cross-reactive T cell recognition
between circulating “common cold” coronaviruses and SARS-CoV-2. See here. https://www.cell.com/cell/fulltext/S0092-8674(20)30610-3
A preprint last month from a team at Oxford came to a similar conclusion. https://www.biorxiv.org/content/10.1101/2020.06.05.134551v1.full
Of course, we don't yet know how much protection T cells provide, but the fact that the number of infections and deaths is falling in all European countries that have eased lockdown restrictions, as well as in those European countries that avoided lockdowns altogether, in spite
of most seroprevalence surveys showing that <10% of the populations in those countries have IgG antibodies, suggests something is functioning as a prophylactic against the disease – referred to as immunological "dark matter" by Professor Karl Friston at @ucl.
T cell mediated
T cell mediated
immunity could be that immunological dark matter. It would explain why young people are less susceptible to the virus – the reservoir of programmable T cells declines with age.
In a recent article in the @ConversationUK, a Professor of Genetic Epidemiology and a Professor of
In a recent article in the @ConversationUK, a Professor of Genetic Epidemiology and a Professor of
Epidemiology, speculate that T cell mediated immunity could mean a "population can achieve some sort of immunity to the virus with as little as 20% infected – a proportion well below the widely accepted herd immunity threshold (60-70%)." https://theconversation.com/coronavirus-could-it-be-burning-out-after-20-of-a-population-is-infected-141584
If that's the case, the UK could have achieved herd immunity already – remember, seroprevalence surveys only measure the percentage of the pop that has developed IgG antibodies, not the percentage that's been exposed to infection.
Another recent study, this one from the
Another recent study, this one from the
University of Nottingham, estimated the disease-induced herd immunity level is around 43%. https://pubmed.ncbi.nlm.nih.gov/32576668/
You made the point in your thread that we don't know if having had the disease confers immunity. True, but the fact that there hasn't been a single, uncontested case of reinfection is a reason to be optimistic. IgG immunity may fade, but even undetectable levels of IgG antibodies
would mean a person who did become reinfected would likely get a milder version of the disease than they had the first time, as @BallouxFrancois says. He also points out that T cell mediated immunity is "extremely long-lived".
So suggesting that the UK will soon achieve herd
So suggesting that the UK will soon achieve herd
immunity, as I did in the @Telegraph, does not make me "scientifically illiterate" or "ignorant" or a "pub bore" or "dangerous", as you claim. You write as if there is a single scientific consensus on SARS-CoV-2 – "the science" – and anyone who dissents from it is an
ideologically-driven purveyor of fake news. In fact, there's very little about the virus, particularly its prevalence and lethality, that is uncontested. Rather, there's a wide range of views, each with eminent scientists to back them up, along with plenty of research and data.
You often present yourself as an exemplar of best practice when it comes to scientific debate and inquiry, but then, in the next breath, engage in furious, ad hominem attacks on those who disagree with you. It's as though your self-important, attention-loving self gets the better
of your dispassionate, scientific self. For a journalist claiming to be an advocate for the better public understanding of science, this sophomoric name-calling is counter-productive. Perhaps take a break from Twitter? //ENDS
