Fully vaccinated individuals have a much greater chance of not being impacted by COVID-19, whether that impact is via infection, hospitalization, or death, according to new reports by the Center for Disease Control and Prevention (CDC).
CDC’s data shows that not fully vaccinated people are over 10 times more likely to be hospitalized from COVID-19 and over 10 times more likely to die from it. Not fully vaccinated people are also five times more likely to catch COVID-19 than vaccinated people.
Across 13 U.S. jurisdictions, incidence rate ratios for hospitalization and death changed relatively little after the SARS-CoV-2 B.1.617.2 (Delta) variant reached predominance, suggesting high, continued vaccine effectiveness against severe COVID-19. Case IRRs decreased, suggesting reduced vaccine effectiveness for the prevention of SARS-CoV-2 infections.
CDC’s report also says that the findings in this report are subject to at least five limitations. First, combining unvaccinated and partially vaccinated persons resulted in lower IRR and VE estimates.
Second, variable linkage of case surveillance, vaccination, hospitalization, and mortality data might have resulted in misclassifications that could influence IRR estimates; no substantial differences in the ascertainment of outcomes by vaccination status were noted in jurisdictions that were able to assess this. Lags in reporting of deaths might have affected the second period differentially.
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Third, this was an ecological study in which IRRs lacked multivariable adjustments and causality could not be assessed (i.e., possible differences in testing or behaviors in vaccinated and unvaccinated persons). VE is being assessed through ongoing controlled studies.
Fourth, the period when the SARS-CoV-2 Delta variant reached ≥50% overall prevalence was assumed to be the first week when most cases were infected with the Delta variant, but the week varied by jurisdiction.
Finally, the data assessed from 13 jurisdictions accounted for 25% of the U.S. population, and therefore might not be generalizable.
The takeaway from the CDC’s data seems clear: Fully vaccinated individuals have a much greater chance of not being impacted by the disease, whether that impact is via infection, hospitalization, or death.
