New coronavirus vaccines are now approved. Here’s what to know.

The Food and Drug Administration approved new mRNA coronavirus vaccines Thursday, clearing the way for shots manufactured by Pfizer-BioNTech and Moderna to start hitting pharmacy shelves and doctor’s offices within a week.

Health officials encourage annual vaccination against the coronavirus, similar to yearly flu shots. Everyone 6 months and older should receive a new vaccine, the Centers for Disease Control and Prevention recommends.

The FDA has yet to approve an updated vaccine from Novavax, which uses a more conventional vaccine development method but has faced financial challenges.

Our scientific understanding of coronavirus vaccines has evolved since they debuted in late 2020. Here’s what to know about the new vaccines.

Why are there new vaccines?

Coronavirus keeps evolving to overcome our immune defenses, and the shield offered by vaccines weakens over time. That’s why federal health officials want people to get an annual updated coronavirus vaccine designed to target the latest variants. They approve them for release in late summer or early fall to coincide with flu shots that Americans are already used to getting.

The underlying vaccine technology and manufacturing process are the same, but components change to account for how the virus morphs. The new vaccines target the KP.2 variant because most recent COVID cases are caused by that strain or closely related ones.

COVID is less dangerous overall than it was earlier in the pandemic because our bodies have become used to fighting the virus off and nearly everyone has some degree of immunity from receiving shots or getting sick. A new shot is meant to shore up existing defenses.

“It’s an opportunity to mitigate or to reduce that risk even further rather than just relying on what happened in the past,” said Robert Hopkins Jr., medical director of the National Foundation for Infectious Diseases and a physician in Arkansas.

Who needs a new coronavirus vaccine?

The United States differs from other countries in recommending an updated coronavirus vaccine for everyone except young infants, rather than just those at heightened risk for severe disease because they are 65 or older, are moderately to severely immunocompromised or have serious medical conditions.

Health officials rejected a more targeted recommendation, with some contending that it’s easier to tell everyone to get vaccinated than to try to define what makes a person high-risk. Most Americans have a risk factor for severe COVID, such as being overweight or having diabetes.

Critics of this approach, including Paul A. Offit, a pediatrician and director of the Vaccine Education Center at Children’s Hospital of Philadelphia, worry that it detracts from the urgency of vaccinating vulnerable people who have a harder time mounting an immune response to the coronavirus.

Do the vaccines prevent infection?

You probably know by now that vaccinated people can still get COVID. But the shots do offer some protection against infection, just not the kind of protection you get from highly effective vaccines for other diseases such as measles.

The 2023-2024 vaccine provided 54 percent increased protection against symptomatic COVID infections, according to a CDC study of people who tested for the coronavirus at pharmacies during the first four months after that year’s shot was released.

“People who get vaccinated are much less likely to get infected in the first place,” said David J. Topham, director of the University of Rochester Translational Immunology and Infectious Disease Institute. “We’d love vaccines to be perfect, but Mother Nature is pretty damn smart.”

A nasal vaccine could be better at stopping infections outright by increasing immunity where they take hold, and one is being studied in a trial sponsored by the National Institutes of Health.

If you really want to dodge COVID, don’t rely on the vaccine alone and take other precautions such as masking or avoiding crowds. But if you want to carry on with life as normal, a new vaccine lowers your risk of getting COVID - at least in the short term.

Do the vaccines help prevent transmission?

You may remember from early coverage of coronavirus vaccines that it was unclear whether shots would reduce transmission. Now, scientists say the answer is yes - even if you’re actively shedding virus.

That’s because the vaccine creates antibodies that reduce the amount of virus entering your cells, limiting how much the virus can replicate and make you even sicker. When vaccination prevents symptoms such as coughing and sneezing, people expel fewer respiratory droplets carrying the virus. When it reduces the viral load in an infected person, people become less contagious.

That’s why Peter Hotez, a physician and co-director of the Texas Children’s Hospital Center for Vaccine Development, said he feels more comfortable in a crowded medical conference, where attendees are probably up to date on their vaccines, than in a crowded airport.

“By having so many vaccinated people, it’s decreasing the number of days you are shedding virus if you get a breakthrough infection, and it decreases the amount of virus you are shedding,” Hotez said.

How long does vaccine protection last?

CDC data shows that the effectiveness of the 2023-2024 vaccine, meant to reduce emergency room visits and hospitalizations, declined sharply more than four months after receiving it. But the risk of hospitalization still remains low for most people, which made it harder for the CDC to compare outcomes for people who received an updated shot with those who did not.

The CDC usually recommends a second dose for those at greatest risk, rather than everyone.

Vaccines create antibodies that target the spike protein of a virus that enters a cell, but the spike protein is often evolving to overcome them or avoid detection. Other elements of the immune response, such as killer T cells, are more durable and recognize the additional parts of the virus that are not mutating.

“Once the virus gets in, [T-cells] can kill off infected cells,” Topham said. “They can slow the infection down. They can prevent it from spreading throughout the body. It shortens your disease.”

Do vaccines prevent long COVID?

While the threat of acute serious respiratory COVID disease has faded, developing the lingering symptoms of “long COVID” remains a concern for people who have had even mild cases. The CDC says vaccination is the “best available tool” to reduce the risk of long COVID in children and adults. The exact mechanism is unclear, but experts theorize that vaccines help by reducing the severity of illness, which is a major risk factor for long COVID.

When is the best time to get a new coronavirus vaccine?

It depends on your circumstances, including risk factors for severe disease, when you were last infected or vaccinated, and plans for the months ahead. It’s best to talk these issues through with a doctor.

If you are at high risk and have not recently been vaccinated or infected, you may want to get a shot as soon as possible while cases remain high. The summer wave has shown signs of peaking, but cases can still be elevated and take weeks to return to low levels. It’s hard to predict when a winter wave will begin.

If your priority is to avoid getting sick ahead of the holidays or a major event such as an international vacation, you could get your vaccine a month ahead of the event to increase your protection.

If you were recently vaccinated, the FDA advises waiting two months since your last shot to get the updated vaccine. The CDC has previously said people can wait three months after an infection to get vaccinated.

Manisha Juthani, Connecticut’s public health commissioner, said people who have recently had COVID could time their next vaccine several weeks before a holiday, when they will be exposed to a lot of people, whether that’s Halloween, Thanksgiving or end-of-year celebrations.

Where do I find vaccines?

Coronavirus vaccines are sold as a commercial product and are no longer purchased and distributed by the federal government for free. That means they won’t be as readily accessible as they once were, but they shouldn’t be too hard to find.

CVS said it expects to start administering them within days, and Walgreens said that it would start scheduling appointments to receive shots after Sept. 6 and that customers can walk in before then.

Availability at doctor’s offices might take longer. Finding shots for infants and toddlers could be more difficult because many pharmacies do not administer them and not every pediatrician’s office will stock them given low demand and limited storage space.

This year’s updated coronavirus vaccines are supposed to have a longer shelf life, which eases the financial pressures of stocking them.

The CDC plans to relaunch its vaccine locator when the new vaccines are widely available, and similar services are offered by Moderna and Pfizer.

Are coronavirus vaccines free?

Most insurance plans are required to cover recommended vaccines under the Affordable Care Act, but some may not cover shots administered by out-of-network providers. Officials say billing code errors and failure to updates systems that led to improper charges last year should mostly be resolved, but if you are still getting charged for vaccines, you or your provider should contact your insurance company or appeal to the agency that regulates your plan.

The federal Bridge Access Program, which provided free coronavirus vaccines to people without health insurance, ends this month. People might be able to find other assistance through federally qualified health centers, local health departments or nonprofit groups.

Can you get your COVID and flu shot together?

Public health officials encourage receiving COVID and flu shots in the same visit as a way to increase vaccination rates, and say that no serious side effects associated with co-administering the vaccines have been identified.

But if you are someone who will get both vaccines no matter what, it could be beneficial to space them apart. Flu shots are best administered in September or October, so it might make sense to get a flu shot first with a coronavirus vaccination later if you already had COVID this summer.

Coronavirus vaccine manufacturers are working on combination flu/coronavirus shots. Moderna reported promising trial results that keep it on track to go to market as early as fall 2025. Pfizer-BioNTech reported mixed results from its trials, a setback.