A study today in Morbidity and Mortality Weekly Report shows that US nursing home residents who received a second mRNA COVID-19 vaccine booster dose 60 days earlier were 26% protected against Omicron infection, 74% against hospitalization or death, and 90% against death alone.

A team led by researchers from the Veterans Administration Medical Center in Providence, Rhode Island, monitored the electronic health record data of residents of 196 Genesis HealthCare nursing homes in 19 states who received their second mRNA COVID-19 booster (primary series plus two booster doses) from Mar 29 to Jun 15, 2022, until Jul 25. There was a median of 49 residents per facility.

Of the 9,527 residents, 3,245 (34.1%) received a second booster dose.

In a matched analysis, 1,902 residents were paired in a 1:1 ratio with controls (1,343 residents weren't included because they couldn't be matched with a control). Average age was 78 years, and about 35% were men. The study period spanned the predominance of the Omicron subvariants BA.2 and BA.2.12.1 (March to June) and BA.4, and BA.5 (July).