Government funded research has found that coronavirus infections in care home residents fell by 62% from five weeks after they received their first vaccine dose and that they may also be less likely to transmit the virus.
The initial findings from the Vivaldi study, led by researchers from University College London, examined data on 10,412 elderly care home residents from 310 care homes between December and mid-March. They looked at the number of infections confirmed with PCR tests within specific time periods after vaccination and compared this to the number of infections that occurred before vaccination.
They calculated the risk of infection was 56% lower from four weeks after a single dose of either the Pfizer or Oxford-AstraZeneca vaccine, and 62% lower after five weeks.
The authors say this early finding requires further study, as just 11% of the participants had previously contracted the virus.
Further research is also needed to examine how effective a first dose is after eight to 12 weeks, and the impact of a second dose.
This will feed into policy decisions regarding the ongoing need for disease control measures in care homes, such as visitor restrictions, which the authors note continue to have a detrimental impact on families.
In her statement to The Mirror, Laura Shallcross, from UCL's Institute of Health Informatics, said, "Our findings show that a single dose has a protective effect that persists from four weeks to at least seven weeks after vaccination.
"Vaccination reduces the total number of people who get infected and analysis of lab samples suggests that care home residents who are infected after having the vaccine may also be less likely to transmit the virus."
