The recent discussion and governmental approvals of a third “booster” shot of the Pfizer COVID-19 vaccine for certain groups has sparked a great deal of interest and dialog.

While some people have experienced side effects from vaccines, the number is very small compared to the number of people dying from COVID-19, says Dr. Melissa Martinez, professor in The University of New Mexico Department of Internal Medicine.

“Vaccines have been used by people for many years and are safe and very effective,” she says. “In the United States alone, more than 300 million COVID-19 dosages have been given.”

The U.S. Centers for Disease Control and Prevention has reviewed data that show the antibodies generated by vaccines may wane over time and therefore be less able to protect against the Delta variant of the coronavirus, she says.

“The new booster will make the immunity work better, and it makes the duration of the immunity work better,” Martinez says. “It is not surprising at all to see that eventually we may need additional dosages of COVID-19 vaccine.”

Does the fact that we need a third shot mean something is wrong with the vaccine?

“No. Historically, many vaccines have required boosters over time, and it is not surprising that this would also apply to the COVID-19 vaccine,” she says.

That doesn’t mean that people should panic: “With two shots, people have some protection against hospitalization and severe illness. The third shot will help with that, so there is no need to panic,” Martinez says.

Is the booster going to be a different formulation or is it the same as the first shots?

“At this time, it is the same vaccine as the first two shots — it is just the third dose. But that could change in the future,” she says.

What about side effects and the booster?

“As you give progressively more vaccination, the chances of side effects such as muscle aches and a low fever may increase somewhat,” Martinez says.

Will there be additional mass vaccination sites?

The New Mexico Department of Health is formulating schedules for vaccination sites, but it is important to remember that things are much different now than in the winter/spring of 2020-21. The vaccine is much more available now and is at pharmacies throughout the state.

What will be the cost of the booster?

Just like with the first two shots, the booster will be free to everyone.

Do I need to do anything else after receiving the booster?

“Don’t forget to maintain all the standard virus-fighting precautions of social distancing, masking and hand washing,” Martinez says. “They work against spreading the virus and help add another wall of protection.”

How long does it take for the booster to build protection against COVID-19?

“It will again probably take a few weeks to become fully effective, but again, vaccinated people have some baseline protection from the first two shots,” she says.

(Cindy Foster is the senior public affairs officer for UNM Health Sciences.)