SARS-CoV-2 Seroprevalence in Children from Western Romania, March to June 2021.

Limited data are available regarding severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence in children. In this study, we assessed for the first time the seroprevalence of SARS-CoV-2 in children from Romania. Serum samples of 379 children were investigated for the presence of SARS-CoV-2 total antibodies. Serologic tests were performed using Elecsys Anti-SARS-CoV-2 electrochemiluminiscence immunoassay that targets the nucleocapsid protein of the virus. The overall seroprevalence of SARS-CoV-2 total antibodies was 46.70%. No significant difference was observed between seropositive and seronegative children according to age groups, gender, and area of residence. Our findings revealed a high SARS-CoV-2 seroprevalence in Romanian children at the end of the third COVID-19 pandemic wave. Results suggest that children, regardless of age, gender, or area of residence, are susceptible to infection with SARS-CoV-2. Seroprevalence in children was similar to the seroprevalence reported in the adult population from Western Romania during the same period of time, March to June 2021.

SARS-CoV-2 Seroprevalence in Western Romania, March to June 2021.

Background and Objectives: The extent of SARS-CoV-2 infection among a population may be assessed by the presence of serum SARS-CoV-2 antibodies, which indicates previous exposure. The aim of this study was to determine the seroprevalence of SARS-CoV-2 infection in the adult population from Western Romania. Materials and Methods: Samples of 2443 consecutive individuals, referred for routine laboratory investigations, were tested for SARS-CoV-2 antibodies using the Elecsys immunoassay that targets the nucleocapsid protein, for identifying the presence of the total antibodies against SARS-CoV-2. Results: The overall SARS-CoV-2 seroprevalence was 45.60%. SARS-CoV-2 seroprevalence was significantly higher in age group 30-49 years (53.94%) compared to age groups 50-69 years (43.53%) and 70-91 years (30.79%) (p < 0.001, p < 0.001, respectively). No significant difference in seroprevalence was observed between females (44.83%) and males (47.05%). Conclusions: Our data revealed a high seroprevalence of SARS-CoV-2 infection in the adult population from Western Romania and indicate the rapid and significant spread of the virus. The estimated prevalence of 45.60% was 6 times higher than the rate of confirmed COVID-19 cases reported in the study area. This indicates the magnitude of virus transmission in the community.

Dynamics of Antibody Response to BNT162b2 mRNA COVID-19 Vaccine: A 7-Month Follow-Up Study.

Background and Objectives: Comprehension regarding immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is limited, and the durability of immune responses after vaccination is currently unknown. Several studies have reported on the antibody response in fully vaccinated individuals with a limited follow-up of the participants, i.e., below 7 months. Materials and Methods: The antibody response to complete vaccination with the BNT162b2 mRNA COVID-19 vaccine was assessed monthly, for 7 months, in 92 healthcare workers, between February 26 and September 26, 2021. The SARS-CoV-2 anti-spike protein IgG (IgGS) antibody was detected using the SARS-CoV-2 IgG II Quant assay (Abbott, Diagnostics Division, Sligo, Ireland), a chemiluminescent microparticle immunoassay (CMIA) with a sensitivity of 98.1% and specificity of 99.6%. Participants were divided into two groups, one for individuals previously infected with SARS-CoV-2 and the other for individuals without previous infection. Results: The median IgGS titers decreased monthly both in previously infected individuals and in the uninfected group. Previously infected individuals had significantly higher median titers of IgGS compared with previously uninfected subjects at all seven time points after complete vaccination (p < 0.001). Conclusions: Seven months after vaccination, the median IgGS titer had decreased by more than 92% both in individuals previously infected with SARS-CoV-2 and in uninfected individuals. However, IgGS antibodies were still detected in all study participants and persisted throughout the 7 months after the second dose of the vaccine. Further studies should be conducted to monitor the antibody response to the BNT162b2 mRNA vaccine beyond 7 months, to assess the need for a new booster dose in order to extend the duration and amplitude of the specific immune response.