Real-word study shows vaccines protect against COVID-19 hospitalization in older adults
Data from a small real-world study demonstrated that receiving two doses of the Pfizer-BioNTech or Moderna COVID-19 vaccine is 94% effective against COVID-19 hospitalization among adults aged 65 years or older, researchers reported in MMWR.
The efficacy of the two messenger RNA vaccines against COVID-19 hospitalization dropped 30 percentage points when study participants received only one dose.
Mark W. Tenforde, MD, PhD, MPH, a member of the CDC’s COVID-19 Response Team, and colleagues noted in the study that clinical trials have demonstrated the vaccines’ high efficacy, but that “evaluation of vaccine effectiveness against severe outcomes in real-world settings and in populations at high risk, including older adults, is needed.”
“These findings are encouraging and welcome news for the two-thirds of people aged 65 and up who are already fully vaccinated,” CDC Director Rochelle P. Walensky, MD, MPH, said in a news release publicizing the study.
“COVID-19 vaccines are highly effective, and these real-world findings confirm the benefits seen in clinical trials, preventing hospitalizations among those most vulnerable,” Walensky said. “The results are promising for our communities and hospitals. As our vaccination efforts continue to expand, COVID-19 patients will not overwhelm health care systems — leaving hospital staff, beds, and services available for people who need them for other medical conditions.”
Tenforde and colleagues used data from two surveillance network encompassing 24 hospitals in 14 states to evaluate the effectiveness of partial or full vaccination with either mRNA vaccine against COVID-19-associated hospitalization among adults aged 65 years and older.
They enrolled 417 patients 187 as case patients and 230 as controls who were hospitalized at one of the sites between Jan. 1 and March 26.
Among the 187 case patients, 19 (10%) had received at least one dose of Pfizer-BioNTech or Moderna vaccine 14 days or more before illness onset, including just one who was fully vaccinated, compared with 62 (27%) of 230 test-negative controls.
According to the authors, the adjusted vaccine effectiveness (VE) was 94% (95% CI, 49%-99%) among fully vaccinated participants and 64% (95% CI, 28%-82%) among partially vaccinated participants.
Additionally, Tenforde and colleagues said there was no significant effect for receiving the first dose of a two-dose mRNA vaccine series within 14 days before illness onset (adjusted VE = 3%; 95% CI, 94% to 51%).
The researchers explained that the confidence intervals for their results were wide because of the study’s small sample size.
The findings were in line with another real-world study that calculated the vaccines reduced the risk for infection by 90% among fully vaccinated heath care personnel.
“SARS-CoV-2 vaccines significantly reduce the risk for COVID-19-associated hospitalization in older adults and, in turn, might lead to commensurate reductions in post-COVID-19 conditions and deaths,” Tenforde and colleagues wrote.