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

Abstract

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.

Effect of vaccination on COVID-19 hospitalizations and mortality

“… 6 In addition, full vaccination reduced the need for ICU admission by 49.7% and mortality by 56.5%. 6 In a retrospective study evaluating 486 hospitalized COVID-19 patients, 4 not having been vaccinated or not having been fully vaccinated were factors associated with increased mortality. In individuals who require hospitalization despite COVID-19 vaccination, the length of hospital stay, the need for ICU admission, and mortality are lower than in unvaccinated individuals.…”

“…Studies have shown that vaccination reduces COVID-19 mortality, COVID-19 severity, and the length of hospital stay. 4 , 6 , 7 Individuals with complete vaccination schedules had higher survival rates in a retrospective study evaluating 854 patients with COVID-19. 6 In addition, full vaccination reduced the need for ICU admission by 49.7% and mortality by 56.5%.…”

“… 4 , 6 , 7 Individuals with complete vaccination schedules had higher survival rates in a retrospective study evaluating 854 patients with COVID-19. 6 In addition, full vaccination reduced the need for ICU admission by 49.7% and mortality by 56.5%. 6 In a retrospective study evaluating 486 hospitalized COVID-19 patients, 4 not having been vaccinated or not having been fully vaccinated were factors associated with increased mortality.…”

“…Estudos já evidenciaram que a vacinação reduz as taxas de mortalidade da COVID-19, a gravidade da doença e o tempo de internação hospitalar. (4,6,7) Indivíduos com esquema vacinal completo tiveram maior sobrevida em um estudo retrospectivo no qual foram avaliados 854 pacientes com COVID-19. (6) Além disso, a vacinação completa reduziu a necessidade de internação na UTI em 49,7%, e a mortalidade em 56,5%.…”

“…(4,6,7) Indivíduos com esquema vacinal completo tiveram maior sobrevida em um estudo retrospectivo no qual foram avaliados 854 pacientes com COVID-19. (6) Além disso, a vacinação completa reduziu a necessidade de internação na UTI em 49,7%, e a mortalidade em 56,5%. (6) Em outro estudo retrospectivo, (4) no qual foram avaliados 486 pacientes hospitalizados por COVID-19, não ter sido vacinado ou ter sido vacinado incompletamente foram fatores associados a maior mortalidade.…”