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Preprint in English | EuropePMC | ID: ppcovidwho-327762


Several studies have reported a waning of the effectiveness of COVID-19 vaccines. We report real-life vaccine effectiveness in Hungary, estimated with the screening method, in 2021, i.e., covering the dominance of both the Alpha and the Delta variant, and including the booster roll-out. Hungary is in the unique position to use six different vaccines (including the Sputnik V and Sinopharm vaccines, for which limited evidence was available prior to the present study) in the same, relatively homogeneous population. All vaccines provided high level of protection initially which declined over time. While the picture is different in each age group, the waning of immunity is apparent for all vaccines and especially in the younger age groups and the Sinopharm, Sputnik-V and AstraZeneca vaccines, which performed similarly. This is clearly reversed by booster doses, more prominent for those vaccines, where recipients were more likely to take the booster dose (which were the aforementioned three vaccines). Booster doses were almost exclusively mRNA vaccines. Overall, two vaccines, Pfizer/BioNTech and Moderna tend to produce the best results in all age groups, and even with waning taken into account.

Epidemiol Infect ; 149: e157, 2021 04 27.
Article in English | MEDLINE | ID: covidwho-1203374


Hospital healthcare workers (HCWs) are at increased risk of contracting COVID-19 infection. We aimed to determine the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in HCWs in Ireland. Two tertiary referral hospitals in Irish cities with diverging community incidence and seroprevalence were identified; COVID-19 had been diagnosed in 10.2% and 1.8% of staff respectively by the time of the study (October 2020). All staff of both hospitals (N = 9038) were invited to participate in an online questionnaire and blood sampling for SARS-CoV-2 antibody testing. Frequencies and percentages for positive SARS-CoV-2 antibody were calculated and adjusted relative risks (aRR) for participant characteristics were calculated using multivariable regression analysis. In total, 5788 HCWs participated (64% response rate). Seroprevalence of antibodies to SARS-CoV-2 was 15% and 4.1% in hospitals 1 and 2, respectively. Thirty-nine percent of infections were previously undiagnosed. Risk for seropositivity was higher for healthcare assistants (aRR 2.0, 95% confidence interval (CI) 1.4-3.0), nurses (aRR: 1.6, 95% CI 1.1-2.2), daily exposure to patients with COVID-19 (aRR: 1.6, 95% CI 1.2-2.1), age 18-29 years (aRR: 1.4, 95% CI 1.1-1.9), living with other HCWs (aRR: 1.3, 95% CI 1.1-1.5), Asian background (aRR: 1.3, 95% CI 1.0-1.6) and male sex (aRR: 1.2, 95% CI 1.0-1.4). The HCW seroprevalence was six times higher than community seroprevalence. Risk was higher for those with close patient contact. The proportion of undiagnosed infections call for robust infection control guidance, easy access to testing and consideration of screening in asymptomatic HCWs. With emerging evidence of reduction in transmission from vaccinated individuals, the authors strongly endorse rapid vaccination of all HCWs.

Antibodies, Viral/blood , COVID-19 , Personnel, Hospital/statistics & numerical data , Adolescent , Adult , Aged , COVID-19/epidemiology , COVID-19/immunology , Cross-Sectional Studies , Female , Humans , Ireland/epidemiology , Male , Middle Aged , SARS-CoV-2/immunology , Seroepidemiologic Studies , Young Adult