The Ministry of health in Spain published the results of studies showing that antibodies to COVID-19 was detected in 5.2% of the population.
Since the beginning of the pandemic in Spain was recorded over 297 thousand cases of infection, of which more than 28 thousand case proved fatal.
"At present, herd immunity is hard to achieve without accepting collateral damage of many deaths in the susceptible population and overburdening health systems", the authors wrote, according to CNN. Health officials said this week that of the almost 10,000 residents of the city of Bergamo who had blood tests done between April 23 and June 3, approximately 57 percent had antibodies, indicating that they had come into contact with the virus.
"In light of these findings, any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable", said the Lancet's commentary authors, Isabella Eckerle, head of the Geneva Centre for Emerging Viral Diseases, and Benjamin Meyer, a virologist at the University of Geneva. Previous reports show that when a large proportion of the population gets immune to the novel coronavirus, through vaccination, herd immunity can be achieved.
The Spanish study, which tested more than 61,000 people, is the latest to pour cold water over the idea of herd immunity.
The findings suggest that majority of the Spanish population is seronegative to SARS-CoV-2 infection, even in hotspot areas, according to the researchers. The country has the third-highest number of deaths related to population in the world, with 607 deaths per million people, according to Our World in Data.
The eight-week study was conducted by the Carlos III public health institute, which took blood samples from close to 70,000 participants.
The study's lead author, Marina Pollán, told CNN: "Some experts have computed that around 60 percent of seroprevalence might mean herd immunity".
As found in antibody studies elsewhere in the world, Spain's most densely populated areas - the cities of Madrid and Barcelona - had the highest levels of antibody prevalence.
This nationwide population-based study aims to estimate the seroprevalence of SARS-CoV-2 (coronavirus) infection in Spain at the national and regional level.