Staff in care homes should be tested for Covid-19 on a weekly basis, the commissioner for older people in Northern Ireland said.
Virologists support the plan to pick up asymptomatic cases sooner, Eddie Lynch added.
Everyone is checked fortnightly at present, to protect vulnerable residents.
Mr Lynch said: "We need to ramp it up."
He told Stormont assembly members that experts had suggested testing every 14 days was too big a gap, and there was scope for catching coronavirus in between.
"Moving from twice weekly to weekly for care workers would be an appropriate response to the level of risk we are currently seeing."
Regular checking of all asymptomatic staff every 14 days, and asymptomatic residents every 28 days, began in August.
That regime applies to care homes with no suspected or confirmed outbreak.
Mr Lynch said the system so far had been working quite well.
"The authorities are saying it has actually caught a number of asymptomatic cases."
Northern Ireland had the lowest proportion of excess care home deaths in the UK during the early months of the pandemic, research shows.
Half of fatalities with Covid-19 between March and June involved care home residents, the study by academics from the LTCcovid organisation found recently.
Mr Lynch voiced concern at rates of coronavirus infection rising again.
"It is clear that the levels of spread in the community have increased to a markedly higher level unfortunately.
"We do need to be looking at the care workers and nurses living in our community, coming in every day. That is why we need weekly testing."
Age NI chief executive Linda Robinson also gave evidence to Stormont's health committee.
She said: "It is very important that we are following the advice of experts in terms of science and medicine."
She said a timely response could involve increased staff on duty and making sure testing was done effectively.
Some of the homes have 100 beds. "It is not straightforward. You are dealing with people with advanced levels of dementia."