Almost two-thirds of staff and residents in long-term care facilities for older people in England were likely to have been infected with SARS-CoV-2 in the first 2 years of the COVID-19 pandemic, researchers said.
A study by University College London (UCL) concluded that older people in residential homes experienced a "high burden" of infection and associated mortality between March 2020 and March 2022. Researchers estimated an overall infection rate of 65% after 2 years in long-term residential care homes, with residents more likely to have been infected than staff.
The actual cumulative incidence rate could have been even higher, according to the researchers, who said they excluded from their calculations residents who died before sampling began.
Data from the VIVALDI Care Home Infection Study
The study was based on data from UCL's VIVALDI study, which was set up at the outset of the pandemic to find out how many residents and staff in long-term care homes were infected with SARS-CoV-2, as well as the effectiveness of COVID vaccines in protecting them.
Investigators drew on information from 5179 individuals from 220 facilities, of whom 3385 were staff, with a median age of 49 years, and 1794 were residents, with a median age of 87 years. Residents and staff were eligible for inclusion if they had undergone at least one PCR or lateral flow test.
Blood samples from consenting staff and residents were tested for antibodies against COVID-19, with the results linked to data from the national PCR or lateral flow test routine screening programme in long-term care homes which tested all staff weekly, and residents monthly, and more frequently if there was an outbreak or development of symptoms, up to March 2022.
During the 2 years, 2780 individuals had at least one positive antibody test or a positive PCR or lateral flow test. Of those, 998 (35.9%) were residents and 1782 (64.1%) were staff. The median time-at-risk was 438.5 days in residents and 610 in staff. The overall incidence rate was 0.12 cases per 100 person-days and was higher in residents than staff (0.13 vs 0.11).
Results 'Back Reports of High Infection Rates in Residential Care'
Dr Maria Krutikov from UCL's Institute of Health Informatics, who led the study, said: "The comparable incidence of infection between the general population (70% by March 2022) and our care home population of first wave survivors supports reports of high infection incidence in long term care facilities."
She added: "As prior infection and vaccination protects against severe infections, the predominance of previously-exposed residents may explain the recent decline in SARS-CoV-2 deaths in long-term care facilities."
The authors noted limitations to their study, including the observational nature of their investigation and the likelihood that the number of infections might have been underestimated because some individuals died in the first wave of the pandemic before recruitment for blood sampling was in place.
Results from the study, which has yet to be submitted to a journal for publication, is being presented at the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Copenhagen. The study abstract was peer-reviewed by the ECCMID selection committee.
The investigation was funded by the UK Health Security Agency.