Just 5.2% of people in Spain have coronavirus antibodies — far from a so-called herd immunity level, a government study found. In a potentially worrying development, the study also indicated that people’s immunity to coronavirus wanes after just a few weeks.
The third and final phase of a large study across Spain found that 5% of participants had antibodies to coronavirus after the first phase, 5.2% after the second phase and again 5.2% after the third phase.
Spain’s study also found that 7% of participants who had antibodies in the first phase no longer showed them by the second phase, and that about 14% who had them in the first phase had lost them by the third phase, although this final figure requires more study, the Health Ministry said in a statement Monday.
This means that any perceived immunity “can be incomplete, transitory and then disappear,” Dr. Raquel Yotti, head of the Carlos III Health Institute, a key government agency leading the study, said in a news conference on Monday.
More on the study: Spain’s study from April to June involved more than 61,000 participants – which the European Center for Disease Prevention and Control told CNN appears to be the largest to date in Europe.
The study “reflects the difficulty of obtaining herd immunity in the short term,” the Health Ministry statement said.
The medical journal The Lancet on Monday published the peer-reviewed first phase of Spain’s study, which was completed in early May. And in a commentary companion piece, two virologists in Geneva said that herd immunity is “unachievable.”
Spain’s study also found that 10% of health care workers had antibody prevalence and 7.7% of senior care facility workers had antibodies, higher than the national average, the Health Ministry statement said.
Remember: Herd immunity is achieved when enough of a population has become infected with a virus or bacteria – or vaccinated against it – to stop its circulation.
Yotti urged the population, including people who have had Covid-19, to remain cautious and wear masks, maintain social distancing and use hand hygiene.