Association between COVID-19 vaccination type and dose and adverse SARS-CoV-2 outcomes

In recent studies, BMJMore found the association between 2019 coronavirus disease (COVID-19) vaccination or non-vaccination and adverse outcomes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) delta and omicron waves. investigated.

study: Adverse outcomes of SARS-CoV-2 infection with Delta and Omicron variants in vaccinated and non-vaccinated US veterans: a retrospective cohort study. Image credit: MeekoMedia/Shutterstock.com

Background

Studies suggest that vaccine effectiveness declines during the delta period and vaccine breakthrough infections surge. However, SARS-CoV-2 Omicron caused an even greater increase in cases and breakthroughs in the United States.

There is evidence that severe symptoms from SARS-CoV-2 infection are less frequent in vaccinated people than in non-vaccinated people.

Nonetheless, differences in clinical severity of COVID-19 by vaccination status are largely uncharacterized.

Furthermore, few studies have addressed the impact of the third and fourth vaccinations on COVID-19 outcomes, driving vaccination decisions and also risk factors for severe COVID-19. Only minor adjustments were made for potential confounders.

About research

This study investigated the association between COVID-19 vaccination status and severe clinical outcomes in patients from the U.S. Veterans Health Administration.

Adult patients were included on the sampling date of the first SARS-CoV-2-positive test (index day) when the 30-day outcome assessment was initiated.

Only those who tested positive between July-November 2021 (Delta period) or January-June 2022 (Omicron period) were included.

Patients not receiving primary care within 18 and 12 months, respectively, of the index date and inpatients/outpatients were excluded. Reinfection was not considered for analysis.

The primary exposure variable was SARS-CoV-2 vaccination status. Subjects were stratified by vaccine type and number of doses.

Primary outcomes were hospitalization, intensive care unit (ICU) admission, ventilator use, and all-cause mortality. Investigators assessed patients’ clinical and demographic characteristics at baseline.

They applied multivariate logistic regression to examine associations between vaccination status adjusted for patient characteristics and individual outcomes. Models were constructed separately for the SARS-CoV-2 delta and omicron phases.

In addition, the team tested whether results differed by mRNA vaccine manufacturer and time since last vaccination.

Investigation result

95,336 patients tested positive for SARS-CoV-2 during Delta and 184,653 patients during Omicron. They were disproportionately older, male, non-Hispanic Caucasian, and more likely to be vaccinated if infected during the Omicron period.

The proportion of patients receiving 3 doses of vaccine increased to 30.4% in the Omicron phase compared with 1.8% in the Delta phase.

The proportion of patients experiencing adverse COVID-19 outcomes (hospitalization or ICU admission, ventilator, death) was lower in the Omicron stage compared to the Delta stage. Regardless of the number of vaccinations, vaccination was shown to be associated with a lower risk of adverse outcomes than no vaccination.

During the delta period, after adjusting for multiple comparisons, partial mRNA vaccination was associated with increased risk of hospitalization, ventilator use, and death compared with 2 doses of mRNA vaccination. .

Janssen vaccine (Ad26.COV2.S) vaccination was associated with increased rates of hospitalization, ICU admission, and death compared with 2 doses of mRNA vaccine.

A third vaccination did not produce a consistent pattern of association with delta phase outcome. Estimates for the Omicron stage were similar to those for the Delta stage.

However, a third vaccination was associated with a lower risk of hospitalization, ICU admission, ventilator use, and death compared with two vaccinations.

Two doses of Pfizer’s BNT162b2 vaccine increased the odds of hospitalization or ICU admission and ventilator use during both periods compared with two doses of Moderna’s mRNA-1273 vaccine.

Additionally, three doses of BNT162b2 were associated with an increased risk of hospitalization or ICU admission during the Omicron period compared to three doses of mRNA-1273.

Longer post-vaccination associations with adverse outcomes among patients receiving two doses of mRNA vaccine, even when the interval between vaccination and infection was 271 to 365 days was not accepted.

However, after the third mRNA dose, extending the time from vaccination to 91 to 150 days increased the risk of hospitalization and death.

Conclusion

Study Finds Vaccination During SARS-CoV-2 Delta and Omicron Dominance Periods Significantly Reduces Risk of Severe and Fatal COVID-19 Outcomes Among U.S. Veterans proved to do.

Overall, the Omicron period data showed that the third mRNA vaccination, especially the mRNA-1273 vaccine, provided the highest efficacy.