A team of researchers from Stanford University and other California colleges recruited volunteers in Santa Clara County to take blood tests and the stunning results show that 50 times more people than projected have had the coronavirus and now possess the antibodies that makes them immune.

Some 3,000 people volunteered to take a blood test, U.S. Spectator reported:

The result was positive in 1.5 percent of cases. Adjusting for age, gender and ethnicity the results suggest that 2.8 percent of people in the county had already had the virus. That might not seem many, but at the time of the study — on April 4 and 5 — only 1,094 people in the county were recorded as having the virus. The study suggests the real figure is between 48,000 and 81,000.

Like many studies which have been pre-published in order to aid understanding of the COVID-19 pandemic, the paper produced by the Stanford-led team has not yet been peer-reviewed. Moreover, it took place in a part of the United States where very few people have so far tested positive with the virus. It would be interesting to see the experiment repeated in New York City, where recorded infections are far higher.

But it is one more piece in a jigsaw which is slowly building up a picture of a virus which may be far more prevalent — and possibly far less deadly — than was at first believed. As has been argued here before, knowing the general level of infection in the population is absolutely crucial because this informs both the virulence and the mortality rate of the infection. If only a small percentage of the population have had the virus, then it might be worth continuing with lockdown policies. But if SARS-Cov-2 is already endemic in the population there is nothing we can do to stop it but no great reason to try to stop it, either: it has already ripped its way through the population with only a small proportion showing any symptoms.

The Spectator reported on a similar study in northwestern Germany where 15 percent of the population was found to have the antibodies to SARS-CoV-2, the virus strain that causes the novel coronavirus.

“Were that to be reflected in the wider population, it would still mean we were a long way short of the 60 percent infection rate which scientific advisers originally considered necessary for ‘herd immunity’ of the population,” the Spectator reported. “But it would mean we were well on the way.”

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