Just weeks after most cities and states across the country rolled back mask mandates and vaccine requirements, COVID case numbers are rising again due to the BA.2 Omicron subvariant.

Last week, more than 31,000 new cases were reported daily nationwide, a 3% increase from just two weeks ago, according to the New York Times’s COVID database. But in big cities like New York City, where Mayor Eric Adams just tested positive for COVID, cases have increased nearly 40% in the past two weeks, largely because of the emergence of the BA.2 subvariant.

Now some doctors say that rolling back COVID safety precautions may have come too soon, and that the continued rise in cases poses a higher risk to even the most careful followers of COVID safety guidelines.

“Now that all the restrictions have been lifted, people have this idea that the happy days are here again,” Dr. Noah Greenspan, a specialist in cardiovascular physical therapy who treats COVID-19 patients, told Fortune. “But that puts everyone at risk, including those who have been most careful not to expose [themselves] to COVID in the last two years.”

Despite the recent rise in case numbers, it’s unclear whether COVID restrictions will return in many cities.

Dr. Manoj Gandhi, senior medical director at medical instruments maker Thermo Fisher Scientific, said the pandemic is far from over and compared the country’s battle against the virus to a nine-inning baseball game.

“We are probably only in the fourth inning, maybe the top of the fifth,” Gandhi told Fortune. “This virus is not going anywhere anytime soon, and we will end up seeing some [new] different variants down the line.”

In Philadelphia, where there’s been a 50% increase in positive cases in the past 10 days, Mayor Jim Kenney announced on Monday that the city would bring back its indoor mask mandate starting April 18.

“Our city remains open; we can still go about our daily lives and visit the people and places we love while masking in indoor public spaces,” Kenney tweeted in announcing the mandate’s return.

At the federal level, meanwhile, White House COVID-19 response coordinator Ashish Jha said during an appearance on The Today Show Monday that rising COVID cases nationwide were not yet concerning.

“Obviously I never like to see infections rising, and we've got to be careful, but I don't think this is a moment where we have to be excessively concerned," Jha said.

Some experts have also warned of a COVID surge, but because testing isn’t readily available and many Americans who test positive fail to report positive results from at-home test kits, it’s increasingly difficult to gauge just how rampant the virus is now.

“There’s always more spread than we can detect,” Abraar Karan, an infectious disease physician at Stanford University, said in an interview with Bloomberg. “That’s true even more so now than earlier in the pandemic.”

That’s why experts like Gandhi are still advising patients to mask up if they are at risk or at large indoor gatherings, and to get tested regularly.

“It's a good practice for people to just get themselves tested,” Gandhi said. “You might not express symptoms, but you can still harbor [and spread] the virus. If you come back from travel, or were at a place where a lot of people were indoors together…it’s a really good idea to stay on top of things and get tested.”

This story was originally featured on Fortune.com