A study today in Morbidity and Mortality Weekly Report shows that nursing home residents in the United States who received a second booster dose of the COVID-19 mRNA vaccine 60 days earlier were 26% protected against Omicron infection, 74% against hospitalization or death and 90% against death alone.
A team led by researchers at the Veterans Administration Medical Center in Providence, Rhode Island, monitored electronic health record data from residents of 196 Genesis HealthCare nursing homes in 19 states who received their second COVID-19 mRNA booster. 19 (primary series plus two booster doses) from March 29 to June 15, 2022, until July 25. There was a median of 49 residents per facility.
Of the 9527 residents, 3245 (34.1%) received a second booster dose.
In a matched analysis, 1902 residents were matched in a 1:1 ratio with controls (1343 residents were not included because they could not be matched with a control). The average age was 78 and about 35% were male. The study period covered the predominance of Omicron subvariants BA.2 and BA.2.12.1 (March to June) and BA.4 and BA.5 (July).
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A second booster dose of COVID-19 had an estimated 60-day vaccine efficacy (VE) of 25.8% against infection, 73.9% against hospitalization or death, and 89.6% against death alone . The researchers said they included the composite endpoint of hospitalization or death because the hospitalization of a nursing home resident is subject to many other considerations in addition to acute illness.
“General and functional health status, life expectancy, wishes of residents and families, and the general policies of this site are considered,” they wrote. “Some residents might have a low probability of being hospitalized even with severe COVID-19 illness, which might explain not being able to rule out a zero effect to prevent hospitalization alone.”
Also, reporting the death alone is problematic, they said, because if residents are hospitalized or transferred, their deaths might not be noted in nursing home records.
The results demonstrate the importance of second booster doses of COVID-19 in preventing poor outcomes among nursing home residents, the researchers concluded, noting that the relatively short follow-up period made it impossible to assess decline. over time.
“These results suggest that among nursing home residents, second booster doses of the mRNA COVID-19 vaccine provided additional protection over first booster doses against severe COVID-19 outcomes at a time of emergence of Omicron variants,” they wrote. “Facilities should continue to ensure nursing home residents stay up to date with COVID-19 vaccination, including booster doses of the bivalent vaccine.”