tetano
Editor, Senior Moderator
Infect Dis (Lond)
. 2022 Jan 13;1-7.
doi: 10.1080/23744235.2021.2025421. Online ahead of print.
SARS-CoV-2 seroprevalence in Portugal following the third epidemic wave: results of the second National Serological Survey (ISN2COVID-19)
Irina Kislaya[SUP] 1 [/SUP], Paulo Gonçalves[SUP] 2 [/SUP], Verónica Gómez[SUP] 1 [/SUP], Vânia Gaio[SUP] 1 [/SUP], Rita Roquette[SUP] 1 [/SUP], Marta Barreto[SUP] 1 [/SUP], Mafalda Sousa-Uva[SUP] 1 [/SUP], Ana Rita Torres[SUP] 1 [/SUP], Joana Santos[SUP] 1 [/SUP], Rita Matos[SUP] 2 [/SUP], Carla Manita[SUP] 2 [/SUP], João Almeida Santos[SUP] 2 [/SUP], Sofia Soeiro[SUP] 2 [/SUP], Rita de Sousa[SUP] 2 [/SUP], Inês Costa[SUP] 2 [/SUP], Nuno Verdasca[SUP] 2 [/SUP], Raquel Guiomar[SUP] 2 [/SUP], Ana Paula Rodrigues[SUP] 1 [/SUP], ISN2COVID-19 Group
Affiliations
Abstract
Background: Integrated approaches to surveillance of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection are important for public health actions. The 2nd National Serological Survey (ISN2COVID-19) aimed to characterize the extent of SARS-CoV-2 infection and vaccine-induced response in the Portuguese population following the third epidemic wave and the launch of the vaccination campaign.
Methods: A cross-sectional study was performed using data on 8463 Portuguese 1-79 years of age, collected in February and March, 2021. SARS-CoV-2 IgM and IgG (anti-nucleoprotein and anti-spike) antibodies were determined in serum samples using Abbott Architect chemiluminescent microparticle assays. Post-infection and vaccine-induced seroprevalence with 95% confidence intervals (95%CI) were estimated in the overall sample and stratified by population characteristics.
Results: The estimated seroprevalence was 15.5% (95%CI:14.6-16.5%), of which 13.5% (95%CI: 12.6-14.4%) was attributable to natural infection and 2.0% (95%CI:1.7-2.4%) to vaccination. The lowest seroprevelence was observed in persons aged 70-79 years (8.9% 95%CI:6.8-11.6), while seroprevalence in children (14.3%; 95%CI:11.5-17.6%) and adolescents (12.9%; 95%CI:10.5-15.7%) was similar to that of persons aged between 20 and 69 years. Of seropositive individuals, 22.6% (95%CI:19.7-25.9%) did not report any symptoms in 6 months prior to interview. Of persons with completed vaccination (2-doses), 98.6% (95%CI: 93.0-99.7%) had specific IgG (anti-S) antibodies.
Conclusions: After the third epidemic wave, the post-infection SARS-CoV-2 seroprevalence was 1.7 times higher than the cumulative incidence based on PCR-testing, but was higher (2.7 times) in children may be due to the high proportion of asymptomatic and mild infections.
Keywords: COVID-19; Portugal; Seroprevalence; seroepidemiological survey; severe acute respiratory syndrome coronavirus 2.
. 2022 Jan 13;1-7.
doi: 10.1080/23744235.2021.2025421. Online ahead of print.
SARS-CoV-2 seroprevalence in Portugal following the third epidemic wave: results of the second National Serological Survey (ISN2COVID-19)
Irina Kislaya[SUP] 1 [/SUP], Paulo Gonçalves[SUP] 2 [/SUP], Verónica Gómez[SUP] 1 [/SUP], Vânia Gaio[SUP] 1 [/SUP], Rita Roquette[SUP] 1 [/SUP], Marta Barreto[SUP] 1 [/SUP], Mafalda Sousa-Uva[SUP] 1 [/SUP], Ana Rita Torres[SUP] 1 [/SUP], Joana Santos[SUP] 1 [/SUP], Rita Matos[SUP] 2 [/SUP], Carla Manita[SUP] 2 [/SUP], João Almeida Santos[SUP] 2 [/SUP], Sofia Soeiro[SUP] 2 [/SUP], Rita de Sousa[SUP] 2 [/SUP], Inês Costa[SUP] 2 [/SUP], Nuno Verdasca[SUP] 2 [/SUP], Raquel Guiomar[SUP] 2 [/SUP], Ana Paula Rodrigues[SUP] 1 [/SUP], ISN2COVID-19 Group
Affiliations
- PMID: 35023439
- DOI: 10.1080/23744235.2021.2025421
Abstract
Background: Integrated approaches to surveillance of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection are important for public health actions. The 2nd National Serological Survey (ISN2COVID-19) aimed to characterize the extent of SARS-CoV-2 infection and vaccine-induced response in the Portuguese population following the third epidemic wave and the launch of the vaccination campaign.
Methods: A cross-sectional study was performed using data on 8463 Portuguese 1-79 years of age, collected in February and March, 2021. SARS-CoV-2 IgM and IgG (anti-nucleoprotein and anti-spike) antibodies were determined in serum samples using Abbott Architect chemiluminescent microparticle assays. Post-infection and vaccine-induced seroprevalence with 95% confidence intervals (95%CI) were estimated in the overall sample and stratified by population characteristics.
Results: The estimated seroprevalence was 15.5% (95%CI:14.6-16.5%), of which 13.5% (95%CI: 12.6-14.4%) was attributable to natural infection and 2.0% (95%CI:1.7-2.4%) to vaccination. The lowest seroprevelence was observed in persons aged 70-79 years (8.9% 95%CI:6.8-11.6), while seroprevalence in children (14.3%; 95%CI:11.5-17.6%) and adolescents (12.9%; 95%CI:10.5-15.7%) was similar to that of persons aged between 20 and 69 years. Of seropositive individuals, 22.6% (95%CI:19.7-25.9%) did not report any symptoms in 6 months prior to interview. Of persons with completed vaccination (2-doses), 98.6% (95%CI: 93.0-99.7%) had specific IgG (anti-S) antibodies.
Conclusions: After the third epidemic wave, the post-infection SARS-CoV-2 seroprevalence was 1.7 times higher than the cumulative incidence based on PCR-testing, but was higher (2.7 times) in children may be due to the high proportion of asymptomatic and mild infections.
Keywords: COVID-19; Portugal; Seroprevalence; seroepidemiological survey; severe acute respiratory syndrome coronavirus 2.