Antibody response to the COVID-19 virus fell by more than 80% among nursing home residents and staff six months after they completed full COVID-19 vaccination with Pfizer’s drug, according to newly released data.
Although their study has not yet completed peer review, investigators said they were encouraged by the Centers for Disease Control and Prevention to release the data to the public.
The researchers looked at a measure called humoral immunity in blood samples from 120 vaccinated Ohio nursing home residents and 92 staff members. An 80% decrease in immunity over six months was the same in residents, whose median age was 76, and workers, whose median age was 48, said David Canaday, M.D., of the Case Western Reserve University School of Medicine in Cleveland.
The nursing home workers had higher initial antibody levels than residents shortly after vaccination and better maintained them, Canaday and colleagues from Brown University reported. Even so, they also experienced significant declines in immunity over the longer term, according to the study results, published on medRxiv, a preprint server.
The full clinical consequences of a significant drop in humoral immunity remain unclear. But without clinical evidence, it may be necessary to use the data to help decide the advisability of vaccine booster shots — particularly for vulnerable older adults, the researchers said.
“The rapid delta variant spread, vaccine breakthrough in [nursing homes] and community, and rapid antibody decline support CDC’s recommended boosting NH residents to curb spread or prevent severe illness,” they concluded.
Data may support booster shots for residents
Canaday’s earlier research found that many nursing home residents who had never been infected with SARS-CoV-2 showed a far more reduced response in antibodies two weeks after being vaccinated than younger healthcare providers. In that study, 70% of the residents had a “very poor ability to neutralize the coronavirus infection in laboratory experiments,” his team reported.
The current study’s release comes two weeks before Food and Drug Administration advisers are scheduled to consider the need for approving mRNA COVID-19 vaccine booster shots in Americans. These independent experts will specifically discuss recommendations for a Pfizer-BioNTech supplemental Biologics License Application. This would allow administration of a third — or booster — dose of its fully FDA-approved COVID-19 vaccine Comirnaty.
The U.S. government announced in mid-August that it is prepared to offer COVID-19 booster shots to vaccinated Americans beginning on Sept. 20. A booster rollout will depend in part on the results of an FDA safety and effectiveness study and independent data review by the Centers for Disease Control and Prevention’s vaccine advisory committee, according to federal health officials.
Pfizer conducts its own study
In related news, Pfizer CEO Albert Bourla told CNBC that the Comirnaty’s protection against hospitalization dropped from 100% to as low as mid-80% after six months. Those findings are based on a Pfizer-funded study of more than 44,000 people in the United States and abroad. That study also has yet to be peer reviewed, CNBC reported.
Data from that investigation shows a decline in overall vaccine efficacy of 6% on average every two months, according to the researchers.
