The Waning of BNT162b2 Vaccine Effectiveness for SARS-CoV-2 Infection Prevention over Time: A Test-Negative Study in Health Care Professionals of a Health Department from January 2021 to December 2021.

The duration of protection of vaccines against SARS-CoV-2 infection has been evaluated in previous studies, but uncertainty remains about the persistence of effectiveness over time and the ideal timing for booster doses. Therefore, the aim of this study was to evaluate BNT162b2 vaccine effectiveness against SARS-CoV-2 infection in health care workers (HCWs) at a tertiary hospital depending on time elapsed since the completion of a two-dose vaccination regimen. We conducted a case-control with negative test study between 25 January and 12 December 2021 that included 1404 HCWs who underwent an active infection diagnostic test (AIDT) to rule out SARS-CoV-2 infection due to COVID-19 suspicion or prior close contact with patients diagnosed with COVID-19. The adjusted vaccine effectiveness (aVE) for the prevention of SARS-CoV-2 infection 12 to 120 days after completing the full two-dose vaccination regimen was 91.9%. Then, aVE decreased to 63.7% between 121 to 240 days after completing the full two-dose regimen and to 37.2% after 241 days since the second dose. Vaccination against SARS-CoV-2 infection in HCWs remains highly effective after 12 to 120 days have elapsed since the administration of two doses of the BNT162b2 vaccine; however, effectiveness decreases as time elapses since its administration.

[Effectiveness of BNT162b2 vaccine to preventing COVID-19 in healthcare personnel]. / Efectividad de la vacuna BNT162b2 para prevenir la COVID-19 en personal sanitario.

OBJECTIVE: To assess the effectiveness of the vaccine against SARS-CoV-2 (BNT162b2) in healthcare personnel of a health department. METHOD: Test-negative case̶control study. Healthcare personnel with suspected COVID-19 and healthcare personnel close contacts of COVID-19 cases were included between January 27th and June 6th, 2021. They were PCR tested for SARS-CoV-2; those with positive PCR were considered cases and those with negative PCR were considered controls. The adjusted vaccine effectiveness (aVE) to prevent COVID-19 cases and their 95% confidence interval (95%CI) were calculated using the formula VE=(1-odds ratio)×100. RESULTS: 624 healthcare personnel were included, of which 43 (6.9%) were considered cases and 581 (93.8%) controls. The aVE of the complete regimen was 96.3% (95%CI: 82.5̶99.2). The aVE of the incomplete pattern was 68.0% (95%CI: 30.0̶85.4). CONCLUSIONS: The administration of the complete pattern of BNT162b2 vaccine against SARS-CoV-2 is effective for the prevention of cases of COVID-19 in healthcare personnel.

Efectividad de la vacuna BNT162b2 para prevenir la COVID-19 en personal sanitario Effectiveness of BNT162b2 vaccine to preventing COVID-19 in healthcare personnel

Objetivo: Conocer la efectividad de la vacuna BNT162b2 en personal sanitario de un departamento de salud. Método: Estudio de casos y controles con prueba negativa. Se incluyó personal sanitario con sospecha de COVID-19 y personal sanitario que fue contacto estrecho de casos de COVID-19 entre el 25 de enero y el 6 de junio de 2021. Se les realizó prueba de reacción en cadena de la polimerasa (PCR) para SARS-CoV-2;aquellos con PCR positiva fueron considerados casos y aquellos con PCR negativa fueron considerados controles. Se calculó la efectividad vacunal ajustada (EVa) para prevenir casos de COVID-19 y su intervalo de confianza del 95% (IC95%), mediante la fórmula EV = (1 − odds ratio) × 100. Resultados: Se incluyeron 624 profesionales sanitarios;de ellos, 43 (6,9%) casos y 581 (93,1%) controles. La EVa de la pauta completa fue del 96,3% (IC95%: 82,5-99,2) y la de la pauta incompleta del 68,0% (IC95%: 30,0-85,4). Conclusiones: La administración de la pauta completa de vacuna es efectiva para la prevención de casos de COVID-19 en el personal sanitario.

Effectivity of a Program for the Control and Prevention of COVID-19 Healthcare-Associated Infections in a Spanish Academic Hospital.

BACKGROUND: Although recommendations to prevent COVID-19 healthcare-associated infections (HAIs) have been proposed, data on their effectivity are currently limited. OBJECTIVE: The aim was to evaluate the effectivity of a program of control and prevention of COVID-19 in an academic general hospital in Spain. METHODS: We captured the number of COVID-19 cases and the type of contact that occurred in hospitalized patients and healthcare personnel (HCP). To evaluate the impact of the continuous use of a surgical mask among HCP, the number of patients with COVID-19 HAIs and accumulated incidence of HCP with COVID-19 was compared between the preintervention and intervention periods. RESULTS: Two hundred fifty-two patients with COVID-19 have been admitted to the hospital. Seven of them had an HAI origin (6 in the preintervention period and 1 in the intervention period). One hundred forty-two HCP were infected with SARS-CoV-2. Of them, 22 (15.5%) were attributed to healthcare (2 in the emergency department and none in the critical care departments), and 120 (84.5%) were attributed to social relations in the workplace or during their non-work-related personal interactions. The accumulated incidence during the preintervention period was 22.3 for every 1000 HCP and 8.2 for every 1000 HCP during the intervention period. The relative risk was 0.37 (95% confidence interval, 0.25 to 0.55) and the attributable risk was -0.014 (95% confidence interval, -0.020 to -0.009). CONCLUSIONS: A program of control and prevention of HAIs complemented with the recommendation for the continuous use of a surgical mask in the workplace and social environments of HCP effectively decreased the risk of COVID-19 HAIs in admitted patients and HCP.

Frequency, Associated Risk Factors, and Characteristics of COVID-19 Among Healthcare Personnel in a Spanish Health Department.

INTRODUCTION: This study examines the frequency, associated factors, and characteristics of healthcare personnel coronavirus disease 2019 cases in a healthcare department that comprises a tertiary hospital and its associated 12 primary healthcare centers. METHODS: This study included healthcare personnel that showed symptoms or were in contact with a coronavirus disease 2019 case patient from March 2, 2020 to April 19, 2020. Their evolution and characteristics (age, sex, professional category, type of contact) were recorded. Correlations between the different characteristics and risk of developing coronavirus disease 2019 and severe coronavirus disease 2019 were analyzed using chi-square tests. Their magnitudes were quantified with ORs, AORs, and their 95% CIs using a logistic regression model. RESULTS: Of the 3,900 healthcare professionals in the department, 1,791 (45.9%) showed symptoms or were part of a contact tracing study. The prevalence of those with symptoms was 20.1% (784/3,900; 95% CI=18.8, 21.4), with coronavirus disease 2019 was 4.0% (156/3,900; 95% CI=3.4, 4.6), and with severe coronavirus disease 2019 was 0.5% (18/3,900; 95% CI=0.2, 0.7). The frequency of coronavirus disease 2019 in symptomatic healthcare personnel with a nonprotected exposure was 22.8% (112/491) and 13.7% (40/293) in those with a protected exposure (AOR=2.2, 95% CI=1.2, 3.9). The service in which the healthcare personnel performed their activity was not significantly associated with being diagnosed with coronavirus disease 2019. A total of 26.3% (10/38) of male healthcare personnel with coronavirus disease 2019 required hospitalization, compared with 6.8% (8/118) among female healthcare personnel (OR=4.9, 95% CI=1.8, 13.6). CONCLUSIONS: A surveillance and monitoring program centred on healthcare personnel enables an understanding of the risk factors that lead to coronavirus disease 2019 among this population. This knowledge allows the refinement of the strategies for disease control and prevention in healthcare personnel during the coronavirus disease 2019 pandemic.