COVID has been rising and flu is coming. Here’s what you need to know about respiratory virus season in Mass.

The start of fall marks the beginning of respiratory virus season. COVID has been on an upswing for much of the past couple months — and other viruses, including flu and RSV, are still to come.

Experts are hopeful that vaccines and treatments could help prevent the level of illness and death seen the past few winters. One key difference this year is there are vaccines for all three of the major viruses that tend to make people sick: COVID, flu and RSV.

Here’s what you need to know about this season of fevers, coughs and runny noses:

What’s going on with COVID

For much of the summer, COVID was steadily rising in Massachusetts and across the country. The level of virus in Boston-area wastewater increased for a couple months through early September. And the number of COVID patients hospitalized in Massachusetts increased four-fold in about that time.

But by these metrics and others, this COVID upswing has remained far below the level of previous surges. And the virus isn’t hitting most people as hard as it was a couple years ago, because the population has built up immunity from vaccinations and previous infections, according to public health and infectious disease experts. Treatments such as Paxlovid also help prevent severe illness.

“The bad news is every fall and winter since 2020, we have had a significant increase in viral respiratory infections that have strained our health care system,” said Dr. Paul Sax, clinical director of the Division of Infectious Diseases at Brigham and Women’s Hospital. “The good news is that the severity of each individual case of COVID-19 has become progressively lower. And that is a huge piece of good news.”

Other viruses to watch for

In addition to COVID, two other viruses tend to appear every fall and winter: flu and respiratory syncytial virus, or RSV. Like COVID, both can be deadly for higher-risk groups, including older people.

RSV also can be severe for newborn babies and other young children. Last fall, pediatric hospitals were overwhelmed with cases of young children sick with RSV.

Flu and RSV are both expected to pick up in the coming months, though experts can’t predict exactly when. Flu tends to peak later in the season, around February — while RSV tends to come earlier, said Dr. Ashish Jha, dean of Brown University’s school of public health.

“Timing can vary year to year,” Jha said.

The role of vaccines

The COVID vaccine has been updated to better match the strains of the virus that are currently circulating. In this way, it’s becoming more like the flu vaccine, which also is updated regularly and administered once a year.

This fall, for the first time, there’s also an RSV vaccine for people at highest risk of getting sick from that virus: people 60 and older, and pregnant women, who can pass the protection on to their babies in the first six months of life. Another new option this year is a monoclonal antibody treatment to prevent RSV in young children.

Jha said the vaccines for COVID, flu and RSV are critical for preventing hospitalizations and deaths.

“We are probably at a point where more than a hundred thousand Americans are going to die each fall and winter for a long period of time, unless we do something about it,” said Jha, former White House COVID response coordinator.

“We now have three highly effective vaccines that can prevent a large chunk of those deaths," he said. "So when I think about the fall ahead, I'm really looking at a period where there could be a lot of serious illness, a lot of suffering — but so much of it is preventable.”

Who should get vaccines, and when

The flu vaccine and the COVID vaccine both are approved for everyone 6 months and older. The Centers for Disease Control and Prevention recommends that just about everyone get these shots.

Both vaccines are available now, though some pharmacies and health care providers may still be waiting for their shipments of the new COVID vaccine, which was just approved by federal regulators earlier this month.

Some experts are not convinced that the new COVID shot is essential for younger, healthier people — but there’s consensus that the vaccine is likely to help people at higher risk of getting very sick from COVID.

“We do seem to have great efficacy from this vaccine,” said Dr. Cassandra Pierre, infectious disease physician at Boston Medical Center.

Pierre recommends thinking about the COVID shot the way we tend to think about flu shots — as an annual fall ritual. “We are normalizing, annualizing, this process,” she said.

Doctors say the COVID and flu vaccines should be taken by the end of October — before Halloween — in order to provide protection against illness through the peak winter months. It’s fine to get both vaccines on the same day, they say.

For those eligible for the RSV vaccine, it’s possible to get all three shots on the same day. Doctors also say you can get the COVID and flu shots together, and the RSV vaccine on a different day.

What about masks?

Mask mandates, even in hospitals, have mostly disappeared. Hospital leaders could choose to reinstate masks for employees, patients and visitors if infection numbers rise, but so far few have done so.

At the individual level, infectious disease doctors recommend people at high risk of illness — such as the elderly, and people with underlying medical conditions — wear masks in crowded indoor spaces when COVID numbers swell. It’s also a good idea for those who live with higher-risk people to mask up, Pierre said.

“For everyone else, I think it really just depends on your risk tolerance,” she said. “I personally prefer not to get sick right now. My kids are back in school. I want to keep them in school.”

What to do if you get sick

If you have COVID symptoms, or recently spent time with someone who has COVID, it’s still a good idea to take a test, doctors said — though free COVID tests are not as widely available as they used to be.

No matter what the virus, if you’re coughing, sneezing or have a fever — stay home, experts say.

“It's very reasonable to tell people not to socialize, not to go to work when you're sick,” said Brigham and Women's Sax. “The times when you're most contagious is right around when you're sickest.”

For all respiratory viruses, Sax said, “It’s much better to give yourself a break, and give your colleagues and friends a break, by staying home. Just get better. It takes a few days.”

If you do end up with COVID, CDC guidelines still say you should isolate for at least five days, and wear a mask for 10 days if you have to be around other people.

And remember, the popular decongestant phenylephrine is not actually effective, according to the Food and Drug Administration. Doctors recommend rest, fluids and acetaminophen or ibuprofen instead. Pseudoephedrine and some nasal sprays also may help relieve congestion.

Impact on the health care system

Winter is always a busy time for hospitals as they see rising numbers of patients sick with flu, COVID, RSV and many other ailments. In the past few years, hospitals have sometimes had to delay non-urgent medical care because they were so full of patients who needed to be treated right away.

Pierre is hopeful that scenario will not repeat.

“We will not be seeing — should not be seeing — another season of significant strains on the health care system,” she said. “I certainly don't anticipate that.”

But doctors acknowledged there’s a lot they can’t predict about the timing of respiratory viruses and how hard they will hit.