COVID-19 and flu are both on the rise in Massachusetts. The latest wastewater detection levels of the SARS-CoV-2 virus in the days after Christmas, released Thursday, met or surpassed the post-holiday peak reached this time last year in the Boston area.

The uptick has public health experts urging people to get vaccinated and do what they can to stop the spread of respiratory illnesses.

Dr. Sabrina Assoumou, an infectious disease physician at Boston Medical Center and an associate professor at Boston University, said people are still not getting as severely ill when they contract COVID due to the degree of immunity many have through previous vaccinations or infections.

But still, she pointed to the ongoing deaths due to COVID in the United States, which have stayed above 1,000 per week for the last few months across the country.

“That’s just too many, especially at a time when we have a vaccine that could prevent this,” Assoumou said. “And the reason why you want to get vaccinated right now is because, as we're learning, the virus is changing, and we also have what we call waning immunity. So the protection is waning.”

State data shows that about 18% of Massachusetts residents have gotten a recent COVID vaccine, and about 37% have gotten the flu shot.

Experts advised that the problem isn’t just about how severe the infection is upfront. COVID can turn into long COVID, a wide-ranging set of health problems including brain fog and severe fatigue — some of which can be debilitating — that people can experience for months or even years after being infected. The flu, too, can bring about other long-term health complications.

“Probably the biggest argument around trying to avoid COVID, and even flu for that matter, is that there are higher risks for medical problems after you get these infections,” said Dr. Lou Ann Bruno-Murtha, the division chief of infectious diseases at Cambridge Health Alliance.

“It’s not just the infection itself: it’s that the inflammation caused by the infection puts you at risk for other comorbidities and problems down the road,” Bruno-Murtha added. “And certainly, long COVID is still a thing that we want to avoid — there's previously healthy people that are currently suffering from long COVID. So if you can avoid long COVID, or avoid having a cardiac complication after influenza, you're going to be well ahead of the game.”

A line chart shows a massive spike in winter 2021-2022 and then smaller spikes in the subsequent two winters. It represents levels of viral RNA tied to COVID-19 in the Boston-area wastewater
New wastewater data shows the prevalence of the virus that causes COVID-19 has met or exceeded last year's levels after the holidays.
Courtesy of Massachusetts Water Resources Authority

Assoumou said that, for those who think they’ve been infected, the federal government is making more free COVID tests available.

“If you’re at high risk for complications from COVID, you could consider wearing a high-quality mask in indoor public settings and also trying to avoid crowds,” Assoumou said. “And if you’re sick, please stay home so that we can protect the community.”

The Centers for Disease Control and Prevention recommends that people who test positive for COVID should isolate for at least five days and wear a high-quality mask if they have to be around others, at home or in public. But the CDC recommends continuing to isolate if symptoms persist past five days.

Bruno-Murtha added that there is one bright spot in the respiratory illnesses picture in the state right now: the number of infections caused by RSV is going down.

“The good news is RSV seems to have peaked and is subsiding. So that’s great news for our young children, neonates that are really at risk for that to be a really severe disease,” said Bruno-Murtha.

Public health experts have also been reminding those who get COVID to talk to their doctor about getting treated — promptly — with the antiviral drug Paxlovid, which is highly effective at preventing severe disease after infection.

Some patients and even clinicians have been concerned about what has been described as a kind of viral rebound after the five-day Paxlovid treatment ends.

But Assoumou pointed out that the CDC has looked into that recently and found that there was “no consistent association between treatment and rebound.”

“So I really hope and I wish that we would get the word out, that if your health care professional thinks you're qualified, please take Paxlovid,” Assoumou said. “And I would not worry about rebound, because I would much more prefer to be at home with a stuffy nose than in a hospital because I did not take the Paxlovid.”

Both Assoumou and Bruno-Murtha emphasized that people can safely and conveniently get their flu shot and COVID shot at the same time, and that the current COVID vaccines are effective against the most prevalent variants circulating now.

“We are so fortunate in that regard,” Bruno-Murtha said. “Everything we know — the preliminary, even unpublished data — seems to show that for vaccines: really, really, truly miraculous.”