Sara Khalid, a nurse practitioner, disinfects Gregory Borino, of New Haven, for COVID-19 vaccination. Yehyun Kim /

Coronavirus booster shots are now open to anyone 18 and older nationwide.

The Centers for Disease Control and Prevention and the Food and Drug Administration on Friday approved Pfizer and Moderna’s requests to expand eligibility of those shots to all adults in the United States.

The “unanimous decision carefully considered the current state of the pandemic, the latest vaccine effectiveness data over time and review of safety data from people who have already received a COVID-19 primary vaccine series and booster,” CDC Director Rochelle Walensky said.

“Booster shots … are an important public health tool to strengthen our defenses against the virus as we enter the winter holidays.”

Case rates in Connecticut and the region have edged up recently, prompting state and local officials to encourage fully vaccinated residents to seek a booster shot.

Gov. Ned Lamont and state Public Health Commissioner Manisha Juthani last week publicly urged adult residents to get inoculated ahead of the holidays.

“Get it before Thanksgiving, before Christmas, before all those holidays,” Lamont said, “[and] before we see what’s going on in Maine and Vermont, Rhode Island, and New York – all around us. We’ll be ready.”

Prior to Friday’s federal authorization, boosters were permitted for people 65 and older, anyone 18 and older with underlying health conditions, those 18 and older who live in long-term care settings such as nursing homes, and those 18 and older who work or live in high-risk settings. Qualifying work places included grocery stores, educational facilities, public transit spaces, manufacturing facilities and prisons, among other locations.

Anyone 18 and older who received the Johnson & Johnson vaccine also was eligible to receive a booster shot. Many of the categories were already considered very broad, with as much as 70% of adults in the U.S. qualifying, according to The New York Times.

Here are some key things to know about booster eligibility for all adults.

Where can I get a booster shot?

Pharmacies like CVS and Walgreens are scheduling COVID-19 booster shots. To sign up at a CVS location, click here. For Walgreens, click here.

Many of Connecticut’s hospitals and health systems are also taking appointments. To sign up at a Hartford HealthCare facility, click here. For Yale New Haven Health, click here. For UConn Health, click here. And for Stamford Health, click here.

Several physicians’ offices are administering booster shots. Residents should check with their primary care doctor.

The state has launched a coronavirus vaccine website to help people find appointments: Residents can also dial 2-1-1 for information or to schedule a vaccine. Anyone out of state can call 1-800-203-1234.

Why do health officials recommend the booster?

Clinical trial data show that protection against COVID-19 infection wanes after the initial vaccine dose or doses, though the immunization continues to shield against severe disease and hospitalization.

The lower effectiveness is likely due to decreasing protection as time passes, as well as the greater infectiousness of the delta variant, the CDC reported.

When should I get a booster?

Anyone who received the Pfizer or Moderna vaccines should wait at least six months before getting a booster. Those who received the single-dose Johnson & Johnson are eligible to get a booster two months after their initial dose.

“If you’ve had your shot more than six months ago, your immunity is waning,” Juthani, the state health commissioner, said. “There is no doubt about that.”

Residents can choose a different booster than their original shot. For example, if someone received two doses of Pfizer to begin with, they can get a Moderna booster. Moderna’s booster is half the dosage of its original vaccine, while Pfizer’s is the same dosage.

What side effects might I experience?

Possible side effects include pain, redness and swelling at the injection site; headache; fatigue; chills; fever; nausea; and muscle pain.

“Adults and children may have some side effects from the vaccine, which are normal signs that their body is building protection,” the CDC noted. “These side effects may affect their ability to do daily activities, but they should go away in a few days. Some people have no side effects, and allergic reactions are rare.”

“Serious side effects that could cause a long-term health problem are extremely unlikely following any vaccination, including COVID-19 vaccination,” the agency said.

“Vaccine monitoring has historically shown that side effects generally happen within six weeks of receiving a vaccine dose.”

Didn’t Connecticut already open booster shots to people 18 and older?

Two days before federal agencies expanded eligibility for the booster shots, Lamont said everyone 18 and older in Connecticut should get one.

“If you’re over 18, go get yourself a booster shot right now if you haven’t had one already,” he said. “[If it’s been] six months since your last shot, get a booster shot. I think that’s the right thing to do. Other states around us are getting … a little more infected. We’re not an island. A booster shot will really protect you, your family and our state.”

With case rates rising, a handful of other states had also urged their adult residents to set aside federal guidance and get a booster shot, regardless of whether they qualified. Rhode Island, California, New Mexico, Colorado and Arkansas were among those states. Officials in New York City made a similar pronouncement.

A day after Lamont’s remarks, Massachusetts Gov. Charlie Baker opened booster eligibility to everyone 18 and older.

How many people in Connecticut have received a booster shot?

As of Monday morning, 516,020 people had received a booster in Connecticut, CDC data show, representing 20.2% of the state’s fully vaccinated population.

Jenna is CT Mirror’s Health Reporter, focusing on health access, affordability, quality, equity and disparities, social determinants of health, health system planning, infrastructure, processes, information systems, and other health policy. Before joining CT Mirror Jenna was a reporter at The Hartford Courant for 10 years, where she consistently won statewide and regional awards. Jenna has a Master of Science degree in Interactive Media from Quinnipiac University and a Bachelor or Arts degree in Journalism from Grand Valley State University.