CDC: Moderna Vaccine Shows Highest Efficacy Against Hospitalizations in Healthy Adults

Vaccine effectiveness (VE) against COVID-19 hospitalization among healthy adults was higher for the Moderna mRNA vaccine than for both the Pfizer and Johnson & Johnson vaccines, according to a new analysis of data involving 21 US hospitals.

“Although these real-world data suggest some variation in levels of protection by vaccine, all FDA-approved or authorized COVID-19 vaccines provide substantial protection against COVID-19 hospitalization,” wrote study authors led by Wesley Self, MD, associate professor, Vanderbilt University Medical Center, Nashville, Tennessee, in the Morbidity and Mortality Weekly Report published online September 17, 2021.

To further examine VE of the 3 available COVID-19 vaccines in the US in preventing COVID-19 hospitalizations, Self and colleagues analyzed data from adults aged ≥18 years who were admitted to 21 hospitals across 18 states between March 11 and August 15, 2021.

A total of 3689 patients were included (1682 case-patients and 2007 control-patients) in the analysis, of whom 20% were fully vaccinated with the Pfizer vaccine, 12.7% with Moderna, 3.1% with J&J; 64% were unvaccinated. Overall, the median age was 58 years, 48% were women, 23% were non-Hispanic Black, and 18% were Hispanic.

Researchers found VE against COVID-19 hospitalizations was higher for the Moderna vaccine (93%) than for the Pfizer vaccine (88%) (p=0.011), while VE for both mRNA vaccines was higher than that for the J&J vaccine (71%) (all p<.001).

After 120 days from the time of full vaccination, Moderna’ VE against COVID-19 hospitalization fell slightly to 92% and Pfizer’s decreased significantly to 77% (p<.001), according to study results. There were no data shown for the J&J viral-vector shot after 120 days because only a small number of patients received the vaccine; the VE rate, however, fell to 68% for the single-dose vaccine after 28 days.

“Differences in VE between the Moderna and Pfizer-BioNTech vaccine might be due to higher mRNA content in the Moderna vaccine, differences in timing between doses (3 weeks for Pfizer-BioNTech versus 4 weeks for Moderna), or possible differences between groups that received each vaccine that were not accounted for in the analysis,” suggested researchers.

In addition, a secondary analysis involving 100 healthy volunteers showed that patients vaccinated with the J&J vaccine had significantly lower anti-SARS-CoV-2 antibody response at 2 to 6 weeks after being fully vaccinated compared with mRNA vaccine recipients.

“Understanding differences in VE by vaccine product can guide individual choices and policy recommendations regarding vaccine boosters. All FDA-approved or authorized COVID-19 vaccines provide substantial protection against COVID-19 hospitalization,” concluded researchers.

Study limitations included that it was limited to non-immunocompromised adults, the small cohort of J&J vaccine recipients, follow-up time after being fully vaccinated was limited to approximately 29 weeks, and product specific VE by variant (including against Delta variants) was not evaluated.