Herd immunity doubts as Spanish study finds just 5% of population have Covid antibodies

Hopes of achieving sufficient levels of herd immunity to combat the coronavirus pandemic are unrealistic, a new Spanish study suggests.

The research, outlined in a paper in The Lancet, found that just 5.2% of more than 60,000 people tested three times in as many months had developed coronavirus antibodies.

But “around 70% to 90% of a population needs to be immune to protect the uninfected”, the BBC says.

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Study co-author Dr Marina Pollan, director of Spain’s National Centre of Epidemiology, said that the results show that “Spain is a long way from reaching so-called herd immunity”, reports The Telegraph.

And “it would be very unethical to expose the population to the coronavirus in an indiscriminate way,” she added.

The study paper says that the low rate of antibodies found “despite the high impact of Covid -19 in Spain” indicates that herd immunity “cannot be achieved without accepting the collateral damage of many deaths in the susceptible population and overburdening of health systems”.

Spain has reported almost 251,800 coronavirus infections, and just under 28,400 related deaths, according to latest figures.

Similar studies in China and the US have also found “that most of the population appears to have remained unexposed” to the virus, “even in areas with widespread virus circulation”, the Spanish researchers report.

“Social distance measures and efforts to identify and isolate new cases and their contacts are imperative for future epidemic control,” they conclude.

British Society for Immunology spokesperson Danny Altmann, a professor of immunology at Imperial College London, described the study findings as “sobering”.

The results show that “the challenge is to identify the best vaccine strategies able to overcome these problems and stimulate a large, sustained, optimal, immune response in the way the virus failed to do”, he said.