If you’re looking for a good reason to take common sense precautions to prevent the spread of illness, public officials have three. COVID-19, influenza and the respiratory syncytial virus (RSV) are all in circulation now, creating a “tripledemic” of respiratory ailments.

COVID-19 is now in its third year, and though it is now endemic in the population, it continues to cause illnesses and deaths. Case numbers in Barnstable County have been edging up since mid-November, but those figures are based on tests administered by healthcare providers, which represent only a fraction of all COVID testing.

“I know three or four families that are positive now; none of them report those data to anybody, so we have no clue how much COVID there is,” Chatham health board member Richard Edwards said at the board’s Dec. 19 meeting.

This year’s flu strain has already infected an estimated 13 million people, causing 120,000 hospitalizations, and 7,300 deaths nationwide, according to the CDC. The current influenza vaccine provides good protection, however, and public health officials say it’s never too late to get a flu shot.

“Everyone over the age of six months is eligible for both the flu and COVID vaccines and can receive both vaccines at the same time,” said Dr. Larry Madoff of the Mass. Department of Public Health. “Spending time around more people increases the chances you will be exposed to one or more viruses,” he added.

RSV provides the third piece of this season’s triple threat. The virus typically causes a runny nose or sneezing, decrease in appetite, fever, coughing or wheezing, and the symptoms typically appear in stages rather than all at once, according to the CDC. In very young infants with RSV, the only symptoms may be irritability, decreased activity, and breathing difficulties, but officials say almost all children will have had an RSV infection by their second birthday.

“I guess Cape Cod Hospital is not too bad right now with the RSV, but the hospitals up in the Boston area are overwhelmed with it,” Chatham Health Agent Judith Giorgio said last month.

Public health officials are bracing for a potential jump in cases of all three illnesses related to the holidays. Chatham health board member John Beckley said it would be helpful if people got in the habit of routinely testing for COVID before social gatherings, particularly around the holidays.

“It takes 15 minutes. No cost,” he said.

Once rare and expensive, at-home COVID tests are now universally available.

“The health department has a surplus of COVID testing kits that are available free of charge,” Orleans Assistant Health Agent Kelly Messier told her board on Dec. 15. Whether they’re planning a gathering or getting ready to travel, “if they need to test themselves for whatever reason, they should not be hesitant to come by and get some,” she said. Most towns have free test kits available; call the health department for details.

“We just ordered 3,000 more test kits from the state,” Giorgio said. “People are coming in a lot to get them.”

Avoiding crowded indoor spaces is another effective strategy for reducing infections, officials say.

“They also recommend if you have small children, especially babies, don’t be passing them around” at holiday gatherings, she said. “Because we could be carrying the RSV and pass that on to a child when we have little to no symptoms.”

Stemming the tripledemic also means staying current with vaccinations. Edwards said some conservative political leaders claim that COVID vaccines don’t work, a claim that doesn’t stand up to scientific scrutiny. While the COVID vaccine prevents serious illness in most people, seniors or those with high risk factors can sometimes fall ill anyway, and “those are the ones that show up in the hospital,” he noted. While the COVID vaccine works, some “people don’t want to hear it,” Edwards said.

“It does become very political,” Giorgio admitted. “All we can do is keep giving people the CDC message, which is to do the right thing: to test yourself, don’t go out if you’re sick. They’re recommending people wear masks if they’re in crowded places again. All these things are known to help you from becoming severely ill,” she said.