The epidemiologist Óscar Zurriaga explains what indicators are necessary to know the real situation of Covid-19
Óscar Zurriaga, professor of the Department of Preventive Medicine and Public Health of the University of Valencia (UV), an expert in Epidemiology, warns about the difficulty of having unquestionable figures that report on the real situation of Covid-19. In an article published on the scientific dissemination platform The Conversation, he points out that different indicators must be taken into account, and not just one, to know the situation of the pandemic and the actions to be taken.
28 de october de 2020
“The indicators that are frequently used are the absolute numbers and the cumulative incidence (CI), which report on the total number of cases since the beginning and the change (new cases) that occurs over time, respectively”, highlights Óscar Zurriaga. However, these indicators do not provide information on the real burden of the disease, since they do not provide information on the number of people affected at the population level.
According to the expert, prevalence must be used for this, “an indicator that does reveal how many sick people there are from a population perspective”. In addition, when talking about seroprevalence, not only people who have had or have symptoms are taken into account, but also those who have developed antibodies against SARS-CoV-2.
That is why in Spain a seroprevalence study (ENE-COVID) is being carried out, which reports on the real burden of the disease. In it, a seroprevalence of 5% of the population has been evidenced, with great geographical heterogeneity, so that the coastal areas are less affected than the capital and its surroundings. Taking into account that to achieve group immunity, seroprevalence must range between 20-60%, Spain is a long way from achieving such group immunity.
Zurriaga uses the case of Manaus (Brazil) to reflect the difficulty of having unquestionable figures on the situation of the virus. There, a study pointed out that seroprevalence was between 44% and 66% of the population, which seemed to indicate that group immunity had been achieved, but the current increase in cases there puts that immunity into question.
The expert points to different factors to take into account in order to understand the difficulty of knowing the real situation of Covid-19: the identification of cases requires the performance of a diagnostic test, there may be delays in the notification of cases, the objectives for measurements can be different and also several measurements are used. “It is not the same to have surveillance as an objective for immediate action in public health than to carry out a study”, says Zurriaga.
Original article by clicking here.