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.

The effectiveness of mRNA vaccines to prevent SARS-CoV-2 infection and hospitalisation for COVID-19 according to the time elapsed since their administration in health professionals in the Valencian Autonomous Community (Spain).

The objective was to understand the effectiveness of the BNT162b2 and mRNA-1273 vaccines against SARS-CoV-2 in health professionals(HPs) in the Valencian Autonomous Community(Spain) who had completed a full vaccination regimen, both in terms of preventing infections and avoiding hospitalisations, according to the time elapsed since the vaccine administration. Case-controlled study with negative test results. HPs who had undergone at least one PCR or antigen(Ag) active infection diagnostic test(AIDT) to rule out SARS-CoV-2 infection between 25 January and 18 July 2021 were included. HPs with positive AIDT result were considered as cases and those with a negative result controls. Adjusted vaccine effectiveness(VEa) to prevent SARS-CoV-2 infection and its 95% confidence interval(95% CI) were calculated using the formula VEa = (1 - OR) × 100. The VEa for the prevention of SARS-CoV-2 infection 12 to 120 days after completing the full two-dose vaccine regimen was 91.6%(95%CI[89.6%,93.2%]) for the BNT162b2 vaccine and 95.2%(95%CI[88.3%,98.1%]) for the mRNA-1273 vaccine. After 120 days the VEa was 71.5%(95%CI[67.0%,75.5%]) for the BNT162b2 vaccine and 88.3%(95%CI[75.7,94.4%]) for the mRNA-1273 vaccine. The VEa for prevention of hospitalisation for COVID-19 for the complete two-dose regimen of mRNA vaccines (BNT162b2 and mRNA-1273) was 96.8%(95%CI[76.1%,99.6%]). The administration of the complete regimen of the BNT162b2 and mRNA-1273 vaccine against SARS-CoV-2 was highly effective for the prevention of COVID-19 cases in HPs when 12 to 120 days had elapsed since the second dose. However, said effectiveness decreased as time from the vaccine administration elapsed, although it was maintained for the prevention of hospitalisation of HPs.

Sero-epidemiological study of SARS-CoV-2 infection among healthcare personnel in a healthcare department.

OBJECTIVE: Estimate IgG antibody prevalence against SARS-CoV-2 in healthcare personnel (HCP) of a healthcare department (HD). METHOD: Prevalence study. The presence of IgG antibodies against SARS-CoV-2 was determined in HCP of the HD. Enzyme linked immunosorbent assays (ELISA) tests were used. Field work took place from April 24, 2020 to May 8, 2020. The age, sex, occupation (physician, nurse, etc.) and the work area (Primary Care, Emergency Room, etc.) were gathered. The IgG antibody prevalence was then calculated with its 95% confidence interval (95% CI). To study the association between HCP characteristics and the presence IgG the Chi Square test was used, and to study the magnitude of association, the Odds Ratio (95% CI) was calculated. RESULTS: Of the 4813 HCP in the HD, 4179 (87,1%) participated. Of these, 73,3% (3065) were women and 26,7% (1114) men. The global prevalence of IgG antibodies against SARS-CoV-2 was 6,6% (95% CI: 5,8-7,3). There were statistically significant differences depending on the occupation, from 8,7% (95% CI: 6,9-10,6) on medics down to 3,2% (95% CI: 1,0-8,0) on personnel not associated with health care. The other characteristics did not associate significantly to antibody presence against SARS-CoV-2. CONCLUSION: The SARS-CoV-2 infection frequency in HCP is similar to the estimated in the general population for big cities in Spain. This highlights the effectiveness of the infection control and prevention programme in this healthcare department targeted at healthcare personnel.

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.

[Sero-epidemiological study of SARS-CoV-2 infection among healthcare personnel in a healthcare department]. / Estudio de sero-epidemiología de la infección por SARS-CoV-2 en profesionales sanitarios de un departamento sanitario.

OBJECTIVE: Estimate IgG antibody prevalence against SARS-CoV-2 in healthcare personnel (HCP) of a healthcare department (HD). METHOD: Prevalence study. The presence of IgG antibodies against SARS-CoV-2 was determined in HCP of the HD. Enzyme linked immunosorbent assays (ELISA) tests were used. Field work took place from April 24, 2020 to May 8, 2020. The age, sex, occupation (physician, nurse, etc.) and the work area (Primary Care, Emergency Room, etc.) were gathered. The IgG antibody prevalence was then calculated with its 95% confidence interval (95% CI). To study the association between HCP characteristics and the presence IgG the Chi Square test was used, and to study the magnitude of association, the Odds Ratio (95% CI) was calculated. RESULTS: Of the 4813 HCP in the HD, 4179 (87,1%) participated. Of these, 73,3% (3065) were women and 26,7% (1114) men. The global prevalence of IgG antibodies against SARS-CoV-2 was 6,6% (95% CI: 5,8-7,3). There were statistically significant differences depending on the occupation, from 8,7% (95% CI: 6,9-10,6) on medics down to 3,2% (95% CI: 1,0-8,0) on personnel not associated with health care. The other characteristics did not associate significantly to antibody presence against SARS-CoV-2. CONCLUSION: The SARS-CoV-2 infection frequency in HCP is similar to the estimated in the general population for big cities in Spain. This highlights the effectiveness of the infection control and prevention programme in this healthcare department targeted at healthcare personnel.

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.