A Spanish study has cast doubt on the feasibility of herd immunity as a way of tackling the coronavirus pandemic.
The study of more than 60,000 people estimates that around just 5% of the Spanish population has developed antibodies, the medical journal the Lancet reported.
Herd immunity is achieved when enough people become infected with a virus to stop its spread.
Around 70% to 90% of a population needs to be immune to protect the uninfected.
The prevalence of Covid-19 antibodies was below 3% in coastal regions, but higher in areas of Spain with widespread outbreaks, the report said.