A so-called prevalence or antibody study with blood tests of 70,000 Spaniards found that about 5 percent are infected with the corona virus – many without being aware of it. This study was initiated by the Spanish Ministry of Health in Madrid.
There are big regional differences. In the province of Soria, northwest of Madrid, 14.2 percent of the population had antibodies against SARS-CoV-2. In the region of the capital city that was particularly badly affected, 11.3 percent of the Madrilenians had apparently been infected.
The lowest number of infected people was below two percent in Murcia, Asturias and the Canary Islands.
The five percent infection rate is considered low, but when extrapolated across Spain, it means that 2.3 million people were infected with the corona virus. That is 10 times more than the almost 230,000 cases confirmed by tests.
The problem with the currently available antibody tests is that they are not absolutely reliable. In some cases, infections with other corona viruses are also shown as a positive result, without the person having been infected with the novel corona virus.