(NewsNation) — Many people who got sick over the holidays wonder why they still aren’t feeling back up to speed weeks later.

Many Americans are reporting feeling sick longer with things like COVID-19, the flu and RSV, with some speculating new variants may be to blame.

However, experts say that isn’t the case, with some people experiencing back-to-back infections that tax their immune systems and keep them from healing faster.

Dr. Monica Gandhi, professor of medicine at the University of California, San Francisco, says social distancing during the pandemic could also contribute.

“There is something called immune debt. What we mean by that is that we stayed away from each other for three, four years, we didn’t get exposed to RSV, to influenza as much, those rates really went down,” she said on “NewsNation Now.” “Because we weren’t training our immune systems to fight viruses over the last couple of years, we’re not able to get over it as quickly as we did.”

For those hoping to get better faster, Gandhi suggests making sure you’re up to date on all the vaccines you’re eligible for, stocking up on meds and staying home to stop your illness from spreading to others.

But just because this virus season is bad doesn’t mean next year will be the same.

“Our immune system took a break, and it kind of got lazy,” Gandhi said. “Hopefully, by next season, we’ll have a better kind of immune training to able to fight and get through colds and flus more easily.”