Vaccination Changes the COVID-19 Mortality Predictors

A Brazilian study found that COVID-19 vaccination has changed the profile of who dies from the disease. The study, conducted in São José do Rio Preto and published in the Journal of Infection, sought to identify characteristics linked to increased risk of death in vaccinated individuals.

The retrospective, cross-sectional study utilized data from the SIVEP-Gripe Database, the COVID-19 Immunization State Database, and the local medical reporting systems. The primary outcome of interest was COVID-19-related death in patients with symptoms appearing 15 or mor days after completing a vaccine series.

Upon admission to the hospital with a confirmed COVID-19 diagnosis, the patients were divided into 2 groups based upon whether they were vaccinated (with a breakthrough infection) or unvaccinated.

The investigators specifically looked for COVID-19 seropositivity among individuals with diabetes, chronic heart disease, chronic liver disease, severe asthma, morbid obesity, or who were otherwise immunosuppressed, and who had received 1 or 2 doses of a COVID-19 vaccine. Using binary logistic regression, the investigators identified variables that could predict clinical outcomes. They performed discriminant analysis with p<0.1, estimated by Rao's score test and analyzed with SPSS version 25 software.

From January 5-September 12, 2021, 2777 patients were enrolled in the study. The unvaccinated patients were majority male (56.6%), and the average age upon enrollment was 51.08 years. 71.5% of the patients had 1 or more comorbidity, a profile that aligned with prior studies of hospitalized COVID-19 patients.

Among the vaccinated cohort, the average age was significantly higher, at 73.64 years, and 95.4% had comorbidities. The association between complete vaccination, comorbidities, and advanced age was anticipated, and the investigators emphasized, “The values for Spearman's correlation coefficient confirmed this observation once it was negatively correlated with complete vaccination series when controlling for age and comorbidities (ρ = - 0.005; p = 0.777).”

In the unvaccinated COVID-19 patients, the mortality predictors were age above 60 years, presence of comorbidities, cardiopathy, liver disorder, diabetes, neurological disorder, immunocompromised status, pneumopathy, and kidney disease.

The vaccinated patients had a very different mortality profile. Only age above 59 years and preexisting kidney disorders predicted death in this cohort, results that remained robust in both univariate and multivariate analysis. “This is clear evidence that vaccination is effective as protection and saves lives,” said Maurício Lacerda Nogueira, a professor at São José do Rio Preto Medical School and a corresponding author of the article.

The investigators stressed the importance of understanding the profile of patients at risk of severe or fatal COVID-19, even after full vaccination. They concluded, “Our findings demonstrate how vaccination and nonpharmaceutical interventions have changed the profile of COVID-19 in our population, particularly in terms of predictors of death in hospitalized patients: many comorbidities associated with greater risk in the general population are no longer considered risk factors in vaccinated people.”