The conclusions of the National Covid-19 Serological Survey (ISN COVID-19), carried out between April 27 and June 8 of this year, indicate an increase of about 10% in seroprevalence compared to the third phase of the study (86.4%), which ran from September to November 2021.

The study, promoted by INSA, states that the total seroprevalence was higher in the age group between 20 and 29 years (98.6%) and in the North region (96.8%).

Similar values ​​were also observed in all age groups over 20 years of age, including those over 70 years of age, in which the estimated seroprevalence was 97.2%, according to the INSA in a statement.

The age groups below 10 years of age were those with the lowest seroprevalence (76.2% among 0-4 years and 78.7% among 5-9 years), however, those under 20 years of age were registers a greater increase in seroprevalence compared to the third phase of the survey.

For the authors of the study, these values ​​mainly reflect the high incidence of Covid-19 in the child population, especially during the Ómicron wave, in January 2022.

“Antibody levels were highest in the 50-59 age group and lowest in the under 10 age group, indicating that individuals who were both vaccinated and who had a SARS-CoV-2 infection were remain as those with higher levels of antibodies, as observed in the second and third phases of the ISN COVID-19”, advances the INSA.

According to the study, the Algarve remains the region with the lowest seroprevalence (91.7%), probably related to lower vaccination coverage in the region, while the North is where this value is higher.