Repository logo

Browsing by Author "INS COVID-19 group"

Now showing 1 - 1 of 1
  • Portuguese National Serological Survey to Coronavirus Disease-19
    Publication . Rodrigues, Ana Paula; Guiomar, Raquel; INS COVID-19 group
    Introduction: Seroepidemiological studies allow estimating more precise cumulative incidence when compared with results obtained from the SARS-CoV-2 RNA detection test. In this context, the first Portuguese COVID-19 National Serological Survey (ISN-COVID-19) had as primary objectives to: characterize the extent of SARS-CoV-2 infection; determine seroprevalence in specific age groups and Health Regions; and determine the proportion of asymptomatic SARS-CoV-2 infections within Portuguese population. Methods: ISN-COVID-19 was an observational, cross-sectional study. A non-probabilistic sample of 2,301 people residing in Portugal, aged over 1 year old, was analyzed. Sociodemographic, epidemiological and clinical data were collected using a questionnaire and a blood sample was collected from each participant, at 114 collection points, between May 21-July 8, 2020. SARS-Cov-2 specific IgG and IgM were measured in serum by ELISA. Results: National seroprevalence was 2.9% (2.0-4.2%), being higher than the accumulated incidence of the infection reported by the National Surveillance System (0.44%). The estimated seroprevalence was higher in males than in females (4.1% vs 1.8%). It ranged from 2.2% (0.8-5.5) in the 10-19 age group to 3.2% (1.5-6.7) in the 40-59 age group. At the regional level, seroprevalence varied between 1.2% (0.3-4.0) in Alentejo and 3.5% (1.9-6.3) in Lisbon and Tagus Valley. Age and regional differences were not statistical significant. About 44% of individuals with SARS-CoV-2 antibodies did not report previous COVID-19 symptoms. Conclusions: The estimated value is compatible with a limited extent of infection in the Portuguese population, between March and June. Differences observed between seroprevalence and cumulative incidence of the infection are consistent with the evidence of lesser capacity to capture mild or asymptomatic cases by surveillance systems. These results advise universal maintenance of protection measures.
    2020-11-27Conference object Restricted access Show more