According to the study conducted from the data obtained in the second half of November, Navarra is the community with the highest degree of contagion among the territories of Hego Euskal Herria and with the highest rate of immunity: 14.3%. Data from Carlos III indicate that, behind Navarre, Álava has the highest percentage (12%), followed by Bizkaia (8.4%) and Gipuzkoa (6.4%).

These figures are still far from the percentage that would facilitate group immunity, as, according to a study published this summer in the journal Science, about 43% of the population should have developed antibodies to achieve group immunity in the case of SARS-CoV-2.

If these percentages are crossed with the population of each territory, it can be concluded that more than 275,000 inhabitants of Hego Euskal Herria have developed antibodies against COVID-19 based on the data provided by this study.

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However, it is appropriate to follow up more closely the research data, as in this fourth round the number of people who have shown seroprevalence is lower. That is, in tests conducted in November, fewer people have been detected by rapid tests. Specifically, in Navarre it is 10.8%, in Álava it is 9%, in Bizkaia it is 5.9% and in Gipuzkoa it is 4.6%.

This does not mean that immunity is only held by those who have tested positive in the last round, as according to the researchers low antibody levels can be undetected with the instruments used.

Carlos III has published a report which also identifies other limitations to the research being carried out. Among other things, only “non-institutionalised” citizens have been taken into account, which excludes people living in nursing homes and those living in other institutions.