Connecticut has seen a slight increase in COVID-19 cases over recent weeks, hospital officials say, as federal agencies warn of a potential summer wave of the disease.

At several of the state's major hospitals, officials say they've observed a jump in COVID patients, while stressing that totals remain very low compared to recent years.

"I think we're seeing a little bit of an uptick, but nothing like previous summers," Dr. Ulysses Wu, chief epidemiologist at Hartford HealthCare, said Monday. "I do not see a sustained increase."

Dr. Richard Martinello, medical director for infection prevention at Yale New Haven Health, said both incidental and serious COVID cases had risen there as well, though only slightly.

"We have seen a little bit of an uptick, but I wouldn't say at this point that it's clear we're seeing a substantial change," Martinello said. "If it wasn't for hearing about the CDC's concern I would wonder if this was just part of the normal variation that we're seeing."

Martinello said Connecticut residents concerned about infection should make sure they have received every vaccine dose they're eligible for and consider wearing a mask in crowded public places.

Nationally, officials at the U.S. Centers for Disease Control and Prevention have begun to warn of summer bump, citing rising test positivity, hospitalizations and emergency room visits. Dr. Brendan Jackson, the CDC's COVID-19 incident manager, told NPR last week that cases "are starting to tick back up again" after a long period of decline.

"We've seen the early indicators go up for the past several weeks, and just this week for the first time in a long time we've seen hospitalizations tick up as well," Jackson said. "This could be the start of a late-summer wave."

Though Jackson said the increases are most noticeable in the southeastern part of the country, other regions have seen upticks as well. According to CDC data, Connecticut had experienced a 20 percent week-over-week increase in hospitalizations as of mid-July.

Jordan Peccia, whose lab at Yale monitors New Haven wastewater for signs of COVID-19, said traces of the disease reached a low on June 24 but have approximately doubled since then. Still, Peccia said, even the elevated quantity "translates to very few cases in New Haven."

Wu theorized that the weather could be fueling a rise in COVID cases, as hot summer temperatures drive people indoors.

"I've always said the weather matters," he said. "We have the highest temperature on this globe ever recorded. Everybody's inside."

Monitoring COVID-19 data in Connecticut has become more difficult in recent months, since the state Department of Public Health sharply curtailed its collection and reporting practices. As of June 1, the agency now treats COVID the way it does the flu, reporting cases, hospitalizations and deaths only seasonally, from October to June.

Meanwhile, COVID testing in Connecticut and elsewhere has become less accessible than it was previously, meaning more cases are likely going undetected.

In an email Monday, DPH spokesperson Chris Boyle said the agency continues to monitor COVID "using both statewide surveillance data and national indicators." He said the state had not seen a rise in cases or deaths and that the recent uptick in hospitalizations appeared to be in line with routine fluctuations.

"Connecticut is not seeing a sustained increase in hospitalizations as reported in other parts of the country," Boyle said.

Connecticut has seen slight COVID upticks during some previous summers, though often as a result of new variants, which do not appear to be causing this latest increase.

Martinello said it's difficult to know whether the bump in hospitalizations is the start of a broader trend or merely a blip.

"That's the major question," Martinello said. "Is this just part of what we would think of as normal variation, or is this the start of something bad? Time is going to tell."