How, where, and when to get your COVID-19 booster shot

• The FDA and CDC recommended this week that people 65 years and older and others at high risk of severe COVID-19 get Pfizer booster shots at least 6 months after their second dose.
• Here's a rundown of how, where, and when to get a booster based on your eligibility.

Booster shots are here - for some Americans, at least.

US regulators published their recommendations this week as to who should get a third dose of Pfizer's vaccine. But there were slight differences between the guidelines from the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC).

The FDA authorized Pfizer boosters on Wednesday for people 65 years and older and others at high risk of severe COVID-19. That includes people who are more likely to get sick because of their health status, as well those who are at high risk of exposure to the virus due to where they live and work - such as healthcare workers, teachers and daycare staff, grocery store workers, and residents of homeless shelters or prisons.

Then on Thursday, the CDC recommended Pfizer boosters for people 65 years and older, nursing home residents, and people ages 50 to 64 with underlying medical conditions. The agency said younger adults with underlying medical conditions or those at increased risk of COVID-19 exposure because of their job or living arrangement could consider a booster.

Here's a rundown of how, where, and when to get a third shot based on your eligibility.

Who should get a booster shot, and when?

The FDA authorized a third dose of the Moderna or Pfizer vaccine last month for people with severely weakened immune systems - including people receiving cancer treatment, those with advanced HIV infections, or organ transplant patients. Third doses are necessary for this group, since immunocompromised people don't develop the same protection from two shots as others do.

Scientists also agree that elderly people - those 65 years and older - require boosters, since their immunity from vaccines tends to wane more quickly than average.

But there's less consensus when it comes to the rest of the population.

An independent group of advisors to the CDC out forth its own guidance on Thursday, which recommend Pfizer boosters for nursing home residents, people 65 and older, and all adults with underlying medical conditions. But they do not suggest the shot for healthcare workers, teachers, or prisoners.

Scientists do agree, however, that nobody needs a booster until at least six months after their second dose.

Pfizer's data suggests that its vaccine is highly protective against symptomatic COVID-19 for at least six months. The third dose may help maintain that protection when given 6 to 12 months out.

How do you book a booster appointment?

Roughly 80,000 vaccination locations will offer boosters across the country, according to Jeff Zients, the White House coronavirus response coordinator. For the most part, the shots are available at the same locations where people got their first and second doses - including pharmacies like CVS and Walgreens. Many states have closed their large clinics and drive-through sites, though.

Just like the first vaccines, booster shots are free.

"It will be easy. Just show your vaccination card, and you'll get a booster," President Joe Biden said last month. "No other ID, no insurance, no state residency requirement."

Both Walgreens and CVS are asking people to confirm that they meet either the FDA or CDC's eligibility requirements, though the pharmacies don't require specific documentation.

CVS said boosters will be available at 6,000 of its pharmacies and clinics starting Friday.

Walgreens said people can book appointments over the phone or online starting Saturday. Eligible people can either bring their COVID-19 vaccine card to the appointment or provide evidence of their last two vaccine doses and receive a new card. (People who lost their cards can typically retrieve their record by contacting their state health department or the site where they got vaccinated.)

What about those who got J&J?

People who got the Johnson & Johnson shot will likely need second shots in the future, even though the company has said its jab offers "strong" protection against Delta and other variants of concern.

This week, J&J announced that a second dose of its vaccine led to 94% protection against moderate to severe COVID-19.

Some health experts who got the J&J shot, however, have "topped off" with a shot from Moderna or Pfizer, even though that approach goes against the recommendations.

But do we really need boosters?

For most people, there's no need to run to the pharmacy for a booster right away. Vaccines are still highly effective in preventing severe disease, hospitalization, and death.

"The real problem in this country is not that we need to boost the vaccinated - it's that we need to vaccinate the un-vaccinated," Dr. Paul Offit, who sits on the FDA's vaccine advisory committee, told Insider. "That's the problem. Until we do that, we're going to suffer in this country."

The World Health Organization also opposes any move to offer boosters to the general public while so many people in the world remain unvaccinated.

"It's too soon, really. There isn't enough evidence from enough countries around the world to suggest that the vaccines are indeed failing," Soumya Swaminathan, the WHO's chief scientist, said at a Physicians for Human Rights panel on Monday.

"The main goal of the vaccines is to prevent severe disease and death," she added. "The main goal is not to prevent infection."