Real-life evaluation of incidence and clinical outcomes of COVID-19 among healthcare workers during pre-vaccination and post-vaccination periods: A cross-sectional impact study.

INTRODUCTION: We aimed to evaluate the prevalence and clinical outcomes of COVID-19 in healthcare workers (HCWs) in the pre-vaccination and post-vaccination periods. In addition, we determined factors associated with the development of COVID-19 after vaccination. METHODOLOGY: In this analytical cross-sectional epidemiological study, HCWs who were vaccinated between January 14, 2021, and March 21, 2021, were included. HCWs were followed up for 105 days after the 2 doses of CoronaVac. Pre-vaccination and post-vaccination periods were compared. RESULTS: A total of 1,000 HCWs were included, 576 patients (57.6%) were male, and the mean age was 33.2 ± 9.6 years. In the last 3 months during the pre-vaccination period, 187 patients had COVID-19, and the cumulative incidence of COVID-19 was 18.7%. Six of these patients were hospitalized. Severe disease was observed in three patients. In the first 3 months post-vaccination period, COVID-19 was detected in 50 patients, and the cumulative incidence of the disease was determined to be 6.1%. Hospitalization and severe disease were not detected. Age (p = 0.29), sex (OR = 1.5, p = 0.16), smoking (OR = 1.29, p = 0.43), and underlying diseases (OR = 1.6, p = 0.26) were not associated with post-vaccination COVID-19. A history of COVID-19 significantly reduced the likelihood of the development of post-vaccination COVID-19 in multivariate analysis (p = 0.002, OR = 0.16, 95% CI = 0.05-0.51). CONCLUSIONS: CoronaVac significantly reduces the risk of SARS-CoV-2 infection and alleviates the severity of COVID-19 in the early period. Additionally, HCWs who have been infected and vaccinated with CoronaVac are less likely to be reinfected with COVID-19.

Evaluation of clinical outcomes of vaccinated and unvaccinated patients with hospitalization for COVID-19.

We aimed to compare vaccinated and unvaccinated patients hospitalized with COVID-19 in terms of disease severity, need for intensive care unit (ICU) admission, and death. In addition, we determined the factors affecting the COVID-19 severity in vaccinated patients. Patients aged 18-65 years who were hospitalized for COVID-19 between September and December 2021 were retrospectively analyzed in three groups: unvaccinated, partially vaccinated, and fully vaccinated.A total of 854 patients were included. Mean age was 47.9 ± 10.6 years, 474 patients (55.5%) were male. Of these, 230 patients (26.9%) were fully vaccinated, 97 (11.3%) were partially vaccinated, and 527 (61.7%) were unvaccinated. Of the fully vaccinated patients, 67% (n = 153) were vaccinated with CoronaVac and 33% (n = 77) were vaccinated with Pfizer-BioNTech. All patients (n = 97) with a single dose were vaccinated with Pfizer-BioNTech. One hundred thirteen (13.2%) patients were transferred to ICU. A hundred (11.7%) patients were intubated and 77 (9.0%) patients died. Advanced age (P = 0.028, 95% CI = 1.00-1.07, OR = 1.038) and higher Charlson Comorbidity Index (CCI) (P < 0.001, 95% CI = 1.20-1.69, OR = 1.425) were associated with increased mortality, while being fully vaccinated (P = 0.008, 95% CI = 0.23-0.80, OR = 0.435) was associated with survival in multivariate analysis. Full dose vaccination reduced the need for ICU admission by 49.7% (95% CI = 17-70) and mortality by 56.5% (95% CI = 20-77). When the fully vaccinated group was evaluated, we found that death was observed more frequent in patients with CCI>3 (19.1 vs 5.8%, P < 0.01, OR = 3.7). Therefore, the booster vaccine especially in individuals with comorbidities should not be delayed, since the survival expectation is low in patients with a high comorbidity index.