Spain’s large-scale study on the coronavirus indicates just 5% of its population has developed antibodies, strengthening evidence that a so-called herd immunity to Covid-19 is “unachievable,” the medical journal the Lancet reported on Monday.
The findings show that 95% of Spain’s population remains susceptible to the virus. 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.
The European Center for Disease Control told CNN that Spain’s research, on a nationwide representative sample of more than 61,000 participants, appears to be the largest study to date among a dozen serological studies on the coronavirus undertaken by European nations.
To achieve what epidemiologists call herd immunity, mathematical modelers suggest at least between 60% and 70% of people would need to be immune to SARS-CoV-2, the coronavirus that causes COVID-19.
According to the Mayo Clinic, there are two paths to herd immunity for COVID-19: vaccines and infection.
Vaccines would be the ideal approach, though experts say its effects can wane over time. Another path would be infection, but there’s much still unknown about COVID-19, including if having the virus makes a person immune to future infection.