Design: Multicentre, open-label cluster RCT, one season
Population: 20 nursing homes (3963 beds), Toronto
Primary outcome: Number and size of SARS-CoV-2, influenza and RSV outbreaks
Effect: Rate ratio 1.12 (95% CI 0.78 to 1.58); ED transfers −11.0% (−20.6% to −2.0%)

This open-label cluster randomised trial placed an on-site multiplex PCR instrument for SARS-CoV-2, influenza and RSV, run by trained staff, in nursing homes in Toronto over the 2024–25 season. Twenty homes with 3963 beds took part. It was published in JAMA Internal Medicine in September.

Outbreak number and size did not differ (rate ratio 1.12, 95% CI 0.78 to 1.58). Emergency transfers for confirmed or suspected infection fell by 11.0% (−20.6% to −2.0%), without a difference in deaths. Testing doubled, confirmed diagnoses rose, and antiviral treatment started 2.5 days sooner (−3.1 to −1.9).

Rapid on-site diagnosis did not stop spread, but it let homes treat influenza earlier and keep more residents out of hospital, which the authors estimate at about four transfers avoided per 100 beds a season.

Rapid on-site testing helps most where it shortens time to oseltamivir.
Do not expect testing alone to prevent outbreaks; isolation and vaccination still do that.
Agree an antiviral prescribing pathway alongside any on-site testing.
Consider similar arrangements for long-term care facilities you cover.

Why it matters

It shows the value of rapid diagnosis in long-term care lies in treatment and transfer decisions, not in stopping spread.

The statistics, in plain English

The outbreak rate ratio of 1.12 has an interval crossing 1, so testing made no detectable difference to outbreaks. The transfer reduction is a secondary outcome with an upper limit close to zero (−2.0%), so the benefit could be small. Twenty clusters over one season is a modest trial.