They will provide the health personnel for carrying out the project and will be in charge of adapting the logistics of the study in the way that is considered most appropriate in each territory, ensuring that all the methodological requirements of the study are met.
The role of Primary Health Care services will be especially relevant throughout the entire process.
With this study, the Ministry of Health and the ISCIII, under the Ministry of Science and Innovation, in close collaboration with the Autonomous Communities, intend to estimate the percentage of the Spanish population that has developed antibodies against the new SARS-CoV-2 coronavirus ( concept known as seroprevalence). The information obtained will be extremely relevant for public health decision-making in the State as a whole.
In collaboration with the National Statistics Institute (INE), more than 36,000 Spanish households have been selected, so that the sample has participants from all age groups and geographic locations. In this way, a minimum of 60,000 people will be invited to participate.
The design of the ENE-COVIDl study, whose scientific coordination is carried out at the National Center of Epidemiology of the ISCIII, contemplates the study of all the people who live in the same home, since this facilitates the representativeness of the sample, and also , can allow differentiating between new infections that are produced by community transmission and those that may be occurring within homes.
This design is inspired by the recommendations of the World Health Organization (WHO) for seroprevalence studies against SARS-CoV-2.
Furthermore, the ENE-COVID aims to dynamically assess the evolution of the epidemic, for which purpose several visits will be made to the participants to determine if they develop antibodies throughout the study period.
The sampling carried out provides a representative sample at the provincial, regional and national levels. The sample size by province varies between 900 people in the autonomous cities of Ceuta and Melilla and 6,000 people in Madrid, which allows estimating the seroprevalence of COVID-19 with sufficient precision in all the provinces. In turn, interprovincial population proportionality is preserved, which will result in greater efficiency in both regional and national estimates.
Participants in the ENE-COVID will answer a short questionnaire and serological tests will be carried out to determine if they have antibodies against the virus.
First, they will undergo a rapid blood antibody determination test by immunochromatography, which provides information to know if the person has been infected. This test will be carried out in the home or in a health center, depending on the evolution of the epidemic and the circumstances of each family.
The sensitivity of this test, which only requires a finger prick, is estimated to be greater than 80%, but this information regarding its diagnostic accuracy has been obtained in very specific groups of patients and it is unknown whether it can be extrapolated to the whole of the population.
Therefore, to ensure the reliability of the results and to apply the maximum methodological rigor, it was considered highly recommended to obtain additional blood samples by venipuncture (arm prick) in all those participants who give their consent. The analysis of the serum samples, led by the National Center for Microbiology, will be done using more sophisticated and precise serological techniques.
Thanks to these two tests, which combine different levels of precision, a population estimate of the presence of virus antibodies will be obtained.
Together with these two serological studies, the participants in the study will answer different questions about symptoms and possible sources of infection, using an epidemiological questionnaire that will be collected through a web application to facilitate rapid collection of information.
Information for participants
Households have been randomly selected. Each of them will receive a phone call to inform their residents about the objectives of the ENE-COVID study, request their consent and arrange a home visit or appointment at the health center. Participation in the study is voluntary, but the collaboration of all the selected people is very important so that the study information is a real photo of the situation.
From each participant, the necessary information will be obtained to know the existence of a previous diagnosis of COVID19, the presence or history of symptoms compatible with this disease and the main known risk factors.
Particular attention is being paid to the information offered to the participants, especially regarding the interpretation of the test results. Among other measures, a telephone helpline will be made available to participants to answer questions, and there will be an informed consent document for each member of the household, including one aimed at minors, so that they understand what their participation consists of.
In addition, a training program coordinated by the National School of Health for the health personnel who will carry out the study has been established, and a specific biosecurity protocol has been developed to protect the health of the personnel who will carry out the field work and participating people.