COVID-19, INFLUENZA, AND PNEUMOCOCCUS VACCINAL STATUS AMONG HOSPITALIZED PATIENTS DURING THE COVID-19 PANDEMIC ERA

Background: Little is known about the impact of COVID-19, influenza, and pneumococcus vaccinal status on hospital stays in patients admitted to internal medicine units during and after the COVID-19 pandemic.

Methods: Data on adult patients admitted to the internal medicine division (99% from the emergency care unit), Regional Hospital, Bari, Italy, between June 2020 and December 2023 were extracted from the hospital information system. Vaccine status, medical history, demographic data, and clinical outcomes were analyzed using a multiple linear regression model to determine the factors influencing the length of hospitalization.

Results: A total of2,008 patients were included (F/M = 767/1241; mean age = 73.5±SEM0.3 yrs). Overall, their mean hospital stay was 10±0.2 days and was similar between sexes. The prevalence of patients vaccinated against COVID-19 was 82.6% (doses 1, 2, 3, 4, and 5, respectively = 2.4%, 14.4%, 43.3%, 17.8%, and 4.8%); against influenza, it was 69.6% (doses 1, 2, 3, 4, and 5, respectively = 16.0%, 14.2%, 13.7%, 13.8%, and 11.9%); and against pneumococcus, this was 14.2% (doses 1 and 2, respectively = 12.1% and 2.1%), with no gender difference. The hospital stays before and after any vaccine dose were comparable. Multiple linear regression showed that among all factors (age, sex, and vaccine type and doses), only age was positively correlated with hospital stay (R² 0.04, P= 0.01). The prevalence of patients admitted for severe non-COVID-19 pneumonitis was 4.7%, and those vaccinated against COVID-19 had a shorter average hospital stay than unvaccinated patients (8.7 vs 11.3 days, P=0.03).

Conclusions: Vaccinations are preventive tools for decreasing hospital stays in internal medicine wards. COVID-19 vaccination effectively reduces the hospital stay of patients with severe (non-COVID-19) pneumonitis.