FAQs: Second Booster Shots for COVID-19

The Centers for Disease Control and Prevention (CDC) now recommends certain groups receive a second COVID-19 booster shot. This means that if someone had previously received three Moderna or Pfizer shots, they can now get a fourth shot. For those who received two Johnson & Johnson shots, or a Johnson & Johnson shot and a Moderna or Pfizer booster, they can now get a third shot.

We asked UNC Health infectious diseases specialist David Wohl, MD, to answer some common questions about who needs a second booster and why.

Who needs a second booster?

People eligible for a second booster include those age 50 and older, as well as those 12 years and older who have immune systems that are moderately to severely compromised. Examples of those with weakened immune systems include, but are not limited to, those who have had a solid organ transplant such as a kidney or lung, have advanced or untreated HIV, or are undergoing chemotherapy or receiving other immune-suppressing treatment.

“A study of large numbers of people age 60 and older living in Israel looked at rates of COVID-19 illness in those who had received three shots of the Pfizer vaccine versus those who had four shots of this vaccine. A fourth dose reduced the risk of getting the omicron variant of COVID-19 with symptoms, although this protection started to drop after about a month,” Dr. Wohl says. “However, and this is really important, the people who got a fourth shot had a lower risk of getting very sick with COVID-19, and that protection persisted over the months of follow-up.”

If the COVID-19 vaccines work, why do people need multiple boosters?

A major reason we may need to take periodic booster shots is that the COVID-19 virus has been evolving over time and in ways that make it less recognizable by the antibodies the vaccines tell our bodies to produce.

“To be clear, these antibodies and probably those made following prior infection with COVID-19 still recognize the virus, but just not as well as they recognized early versions of COVID-19. Having higher levels of antibodies helps overcome this problem,” Dr. Wohl says.

Boosters, as the name implies, boost antibody levels to better protect people from new variants that circulate.

If I’m eligible for a second booster, when should I get it?

The timing of a second booster is something people who are eligible for the shot need to consider. It is impossible to accurately predict what new variant may emerge or when, but “there is more and more evidence that keeping antibody levels up helps avoid infection and getting severe COVID-19,” Dr. Wohl says.

If you are eligible and your first booster shot was more than six months ago, you may consider getting the second booster now, given evidence of waning antibody levels over time—even though you are likely still very protected from severe COVID-19.

“Those who are more severely immunocompromised and those who expect to have more opportunities to be infected during work, school, travel or entertainment events may want to get a second shot as soon as they’re eligible, especially when case numbers are on the rise,” Dr. Wohl says. “Others may consider delaying the booster in anticipation of a cold weather surge in COVID-19. However, we have seen surges happen in the summer, too.”

Do booster shots have side effects?

Studies show that a second booster can not only help bump up protection from getting ill with COVID-19 but that it does so safely. As with other booster shots, you may feel arm soreness, achiness and tiredness for about a day. Second boosters are the same dose as the first booster, which was half of the original Moderna dose and the full dose of the Pfizer shot.

“There has been no evidence that a second booster increases the risk of any serious side effects of the vaccines,” Dr. Wohl says.

Where can I get a second booster?

Second booster COVID-19 vaccine shots are available for those who are eligible, including anyone age 50 and older, at the same places that have been giving COVID-19 vaccines. This includes pharmacies and clinics. At UNC Health, appointments for a second booster can be scheduled using My UNC Chart.

Will everyone eventually need a second COVID-19 booster shot?

It is possible a second booster dose may eventually be recommended for everyone for the same reason we needed the first booster: to prolong protective immunity when there’s concern it may be waning. The CDC will study the issue and eventually offer a recommendation on second boosters for the broader population.

Visit unchealthcare.org/vaccine for the latest information on the COVID-19 vaccines.