The COVID-19 immunity survey that will entail testing 60,000 people across Spain will be conducted by the regional governments after all. Its start will be delayed by at least two weeks over the date initially announced by the Spanish authorities, who said on April 7 that the survey would be carried out in two batches of 30K tests each, starting in mid-April.
Spain’s National Statistics Institute (INE) has randomly selected 36,000 homes across Spain in order to conduct a demographically representative survey that will include all the residents in each household. The chosen subjects may opt out of the programme, although the Spanish Health Ministry has emphasised the need to take part in the survey so as to gather data that is reliable and representative. The actual tests will be administered by every region’s own health service staff, mainly in primary care centres, as agreed on Tuesday by the Interregional National Health Service Board. Therefore, it won’t be up to the army to run the tests after all, contrary to the original plan, the so-called Operation Zendal, which intended to have 750 service personnel carry out the testing over three weeks across all of Spain.
The survey aims to estimate the percentage of the population that has developed antibodies against the coronavirus, which is known as seroprevalence. Survey participants, who range from 900 in Melilla and Ceuta up to 6,000 in Madrid, will be asked to take a short questionnaire by means of an application and will then be administered a serologic test to determine whether they have the antibodies. The initial rapid tests will be administered with a prick of the finger at home or at a local health centre —depending on every family’s circumstances— to find out which individuals have been infected.
This rapid test is supposed to have an 80 per cent reliability rate, but the percentage was obtained from testing conducted with very specific groups of people and, therefore, its results cannot be extrapolated. This means that in order to ensure that the survey provides reliable data, a second test will be required by drawing blood from the arm, so long as participants have given their consent.
Fernando Simón, the director of Spain’s Public Health Emergency Coordination Centre, has pledged that the survey’s preliminary results will be available from the end of the first week of testing and they will provide an insight into the number of new positive cases that we will likely see in the coming weeks. Based on the information provided by the survey, the authorities will make “estimations about the actual impact of the pandemic”, Simón said, which will allow them to draft a transition plan and, if necessary, fine-tune the measures they have already adopted.