Just 5% of Spain's population has developed coronavirus antibodies, according to the first results of a serological study conducted by the Spanish government that was announced Wednesday.
The study, which tested the blood of around 60,000 randomly selected participants, suggests that 2.3 million people in Spain have been infected by the virus.
That is around ten times higher than the 228,691 cases that the country has so far confirmed.
If the study is correct, it would bring the fatality rate of the virus to around 1.1% in Spain. So far, the country has confirmed 27,104 deaths.
According to Marina Pollan, the head of the National Center of Epidemiology, around 26% of infections were found to be asymptomatic.
She also said the study found that antibodies were less frequent in children than in the general population.
The rate of antibodies also varied considerably by region. In Madrid, one of Spain's hardest-hit areas, 11.3% of the tested population had antibodies. In regions including Asturias, the Canary Islands and Murcia, immunity was found in less than 2% of the sample.
The results of this study suggest the disease is less widespread than other researchers have thought. In late March, a study by Imperial College London estimated that there had been 7 million cases of coronavirus in Spain.
The study's findings also mean that 95% of Spain's population is still vulnerable to the virus.
According to Johns Hopkins University, for a population to develop herd immunity, usually between 70-90% of the group must have immunity.
The antibody studies were led by the Spanish Health Ministry and the Carlos III Health Institute. Researchers claimed the blood tests were "accurate enough" to use for the study.
