Growing evidence exists that a herd immunity to COVID-19 is "unachievable," according to a large-scale study on the coronavirus conducted in Spain, The Lancet medical journal reported on Monday.

The research, on a nationwide representative sample of more than 61,000 participants, indicated that 95% of Spain's population remains susceptible to the virus, with only 5% having developed antibodies.

These results came despite Spain being one of the countries in Europe hit hardest by the coronavirus and the study starting on April 27, while the nation remained on a strict lockdown, and running through May 11, according to CNN.

A herd immunity is achieved when enough of a population has become infected with a virus or been vaccinated against it, to halt its circulation.

"The relatively low seroprevalence observed in the context of an intense epidemic in Spain might serve as a reference to other countries,” the report states. “Herd immunity is difficult to achieve without accepting the collateral damage of many deaths in the susceptible population and overburdening of health systems."

National Center for Epidemiology director Marina Pollán, the lead author of the Spanish study, emphasized to CNN that "Some experts have computed that around 60% of seroprevalence might mean herd immunity. But we are very far from achieving that number."

Similar research worldwide has been conducted, and "the key finding from these representative cohorts is that most of the population appears to have remained unexposed" to COVID-19, "even in areas with widespread virus circulation," according to a Lancet commentary published with the findings of the Spanish study.

The commentary added that "In light of these findings, any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable."

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