Effectiveness of mRNA booster doses in preventing infections and hospitalizations due to SARS-CoV-2 and its dominant variant over time in Valencian healthcare workers, Spain.

OBJECTIVE: This study aimed to evaluate the effectiveness of SARS-CoV-2 mRNA vaccines in preventing infection and hospitalization among healthcare workers (HCWs) in the Valencian Community (Spain), considering vaccination timing, dose number, and predominant variant. METHODS: A test-negative case-control design estimated vaccine effectiveness against symptomatic disease and hospitalization due to SARS-CoV-2. HCWs who underwent PCR or antigen testing for SARS-CoV-2 from January 2021 to March 2022 were included. Cases had a positive diagnostic test, while controls had negative tests. Adjusted vaccine effectiveness (aVE) was calculated using the formula: aVE = (1 - Odds ratio) × 100. RESULTS: During the Delta variant's predominance, aVE against infection within 12-120 days post-second dose was 64.8 % (BNT162b2) and 59.4 % (mRNA-1273), declining to 21.2 % and 42.2 %, respectively, after 120 days. For the Omicron variant, aVE within 12-120 days post-second dose was 61.1 % (BNT162b2) and 85.1 % (mRNA-1273), decreasing to 36.7 % and 24.9 %, respectively, after 120 days. After a booster dose of mRNA-1273, aVE was 64.0 % (BNT162b2 recipients) and 65.9 % (initial mRNA-1273 recipients). Regardless of variant, aVE for hospitalization prevention after 2 doses was 87.0 % (BNT162b2) and 89.0 % (mRNA-1273). CONCLUSION: The administration of two doses of Moderna-mRNA-1273 against SARS-CoV-2 in HCWs proved to be highly effective in preventing infections and hospitalizations in the first 120 days after the second dose during the predominance of the Omicron variant. The decline in VE after 120 days since the administration of the second dose was significantly restored by the booster dose administration. This increase in VE was greater for the Pfizer vaccine. COVID-19 hospitalization prevention remained stable with both mRNA vaccines throughout the study period.

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.

Effectiveness of the systematic use of antimicrobial filters in the water taps of critical care units for the prevention of healthcare-associated infections with Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa (PA) is the third leading aetiological agent in healthcare-associated infections (HAIs) and the one most frequently found in patients with pneumonia associated with mechanical ventilation. In intensive care units (ICU), its appearance is associated with higher mortality, an increase in the days spent on ventilation, and hospital stay length and costs. Thus, evaluating strategies for preventing these infections is essential for their control. Therefore, our objective was to evaluate the effectiveness of the systematic use of antimicrobial filters in preventing PA infections in critical care units. METHODS: This was an open experimental crossover study. A total of 2,156 patients admitted for more than 24 hours in critical care units were included, 1,129 of them in units with filters, and 1,027 in units without filters. The study groups were followed-up for 24 months and HAIs were checked for the presence of PA. Chi-squared test were used to compare the rate of HAIs between groups and we calculated 95% confidence intervals adjusted by Poisson regression for the rate ratio (RR) of the association magnitude. RESULTS: Both groups were homogeneous in terms of intrinsic and extrinsic patient factors. The incidence of PA infections in the units with filters was 5.5 cases/1,000 hospitalized days and 5.4/1,000 hospitalized days for the units without water filters (RR = 1.09 [0.67-1.79]). CONCLUSIONS: Routine placing antimicrobial filters in the water taps in critical care units was not an effective means of preventing the emergence of HAIs caused by PA.

Estimated Costs Associated with Surgical Site Infections in Patients Undergoing Cholecystectomy.

Among healthcare-associated infections, surgical site infections (SSIs) are the most frequent in Spain. The aim of this work was to estimate the costs of SSIs in patients who underwent a cholecystectomy at the Hospital General Universitario de Alicante (Spain) between 2012-2017. This was a prospective observational cohort study. The Active Epidemiological Surveillance Program at our hospital recorded all the cholecystectomies performed. Risk factors associated with the development of SSIs were determined by multivariate analysis and two homogeneous comparison groups were obtained by using the propensity score. The number of extra days of hospital stay were recorded for patients with an SSI and with the cost per hospitalised day data, the additional cost attributed to SSIs was calculated. A total of 2200 cholecystectomies were considered; 110 patients (5.0%) developed an SSI. The average length of hospital stay was 5.6 days longer among patients with an SSI. The cost per SSI was EUR 1890.60 per patient, with the total cost for this period being EUR 207,961.60. SSIs after cholecystectomy lead to a prolongation of hospital stay and an increase in economic costs. It is essential to implement infection surveillance and control programs to reduce SSIs, improve patient safety, and reduce economic burden.

[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.

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.

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

OBJECTIVE: A first protective dose of vaccine may allow delaying the second dose in a context of low supply. The objective is to assess the effectiveness of a single dose of vaccine against SARS-CoV-2 (BNT162b2) after twelve days of its administration in healthcare personnel (HCP) of a Health Department. METHODS: A case-control study was made. HCP with suspected COVID-19 and HCP close contacts of COVID-19 cases were included between January 27 and February 7, 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 crude (VE) and adjusted (VEa) vaccine effectiveness to prevent COVID-19 cases and their 95% confidence interval were calculated using the formula VE = (1-Odds ratio) x 100. RESULTS: 268 HCP were included, of which 70 (26.1%) were considered cases and 198 (73.9%) controls. The frequency of vaccine exposure in cases was 55.7% vs. 69.7% in controls (p=0.035). The VEa of the first vaccine dose was 52.6% (95%CI: 1.1-77.3). The VEa in the subgroup of HCP studied for suspected disease was 74.6% (CI95%: 38.4-89.5). CONCLUSIONS: One dose of BNT162b2 vaccine against SARS-CoV-2 offers early protection after twelve days of administration. These data could be considered to adapt strategies and consider postponing the second dose in situations of limited vaccine supply in order to achieve the maximum number of people covered with a first dose.

OBJETIVO: Una primera dosis de vacuna protectora permitiría aplazar la segunda dosis en un contexto de suministro escaso. El objetivo de este trabajo fue conocer la efectividad de una dosis de vacuna frente a SARS-CoV-2 (BNT162b2) tras doce días de su administración en personal sanitario (PS) de un Departamento de Salud. METODOS: Se realizó un estudio de casos y controles. Se incluyó a PS con sospecha de COVID-19 y PS que tuvo contactos estrechos con casos de COVID-19 entre el 27 de enero y el 7 de febrero de 2021. Se les realizó una PCR para determinar SARS-CoV-2; aquellos con PCR positiva fueron considerados casos y aquellos con PCR negativa fueron considerados controles. Se calculó la efectividad vacunal cruda (EV) y ajustada (EVa) para prevenir casos de COVID-19 y su intervalo de confianza al 95%, mediante la fórmula EV = (1-Odds ratio) x 100. RESULTADOS: Fueron incluidos 268 PS, de los cuales 70 (26,1%) fueron considerados casos y 198 (73,9%) controles. La frecuencia de exposición a la vacuna en los casos fue del 55,7% frente al 69,7% en los controles (p=0,035). La EVa de la primera dosis de vacuna fue del 52,6% (IC95%: 1,1-77,3). La EVa en el subgrupo de PS estudiados por sospecha de enfermedad fue del 74,6% (IC95%: 38,4-89,5). CONCLUSIONES: Una dosis de vacuna BNT162b2 frente a SARS-CoV-2 ofrece protección temprana tras doce días de su administración. Estos datos podrían considerarse para adaptar estrategias y valorar aplazar la segunda dosis en situaciones de limitación de suministro de vacuna, con el fin de conseguir el máximo número de personas cubiertas con una primera dosis.

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.