A study today in Infection Control & Hospital Epidemiology of more than 44,000 COVID-19 cases in Los Angeles County nursing homes reveals that hospitalizations and deaths per 100 residents fell from 31 and 24, respectively, prior to widespread vaccination to 11 and 7, respectively, afterward from March 2020 to April 2022.
LA County has 383 nursing homes housing more than 35,000 licensed beds. County health officials documented all COVID-19 outbreaks beginning in March 2020. In total 44,279 cases were analyzed from 1,587 outbreaks in 313 nursing homes. The authors defined an outbreak as 1 or more cases in nursing home residents with lab-confirmed COVID-19 infection and no periods of 14 or more days between successive COVID-19 cases in residents.
Biggest outbreaks during Omicron
Through the median outbreak size peaked during the 2021-22 winter, when the Omicron variant dominated COVID-19 transmission in the United States, severity dropped significantly, as most residents were vaccinated.
Despite peak or near-peak outbreak duration and size in the winter surge that followed vaccination, the decline in severe outcomes observed upon vaccine introduction endured.
"Despite peak or near-peak outbreak duration and size in the winter surge that followed vaccination, the decline in severe outcomes observed upon vaccine introduction endured," the authors wrote.
They added, however, "Our study also adds to existing evidence that surges in community transmission are strongly correlated with the spread of SARS-CoV-2 in NHs [nursing homes] … even after widespread vaccine availability."
Eighty-seven percent of hospitalizations and 89% of resident deaths took place before widespread vaccination, or March 2020 through January 2021.