Apr 25, 2022 9:00 AM

Author: University of Utah Health Communications


Información en español

A second COVID-19 booster shot is now recommended for certain individuals. This fourth dose of the COVID-19 vaccine series, or fifth dose for people with immunocompromised conditions, will continue to protect individuals from serious illness, hospitalization, and death from SARS-CoV-2.

A second booster doesn’t mean the first one doesn’t work as well or protect you any less. But research has found that immunity from a COVID-19 vaccine starts to wane after about four months and that breakthrough cases are possible afterward. An additional booster shot optimizes your body’s immune system to fight against severe disease from COVID-19.

New research supports the efficacy of COVID-19 booster doses. Researchers at University of Utah Health and Weber State University found a third dose of mRNA COVID-19 vaccines have been highly effective against the Delta and Omicron variants. The Centers for Disease Control and Prevention (CDC) also found those who were boosted during the Omicron surge were 21-times less likely to die and 7-times less likely to be hospitalized from COVID-19 compared with those who were unvaccinated.

As new variants of COVID-19 continue to emerge, it’s important to stay up to date on vaccinations in order to protect yourself and others from infection. 

You are eligible for a second COVID-19 booster shot if you are:

  • Age 50 or older and received your first booster at least four months ago.
  • Age 12 and older, immunocompromised, and received your first booster at least four months ago.
  • Age 18 and older and received the Johnson & Johnson COVID-19 vaccine and booster. An mRNA booster of Pfizer or Moderna is recommended at least four months after the first booster.

Why are only some people eligible for the second booster shot?

Older and immunocompromised individuals were among the first group to become eligible to get a COVID-19 vaccine and booster shot. Data continues to show these groups are most at risk of serious outcomes from COVID-19 and that a second booster dose could help increase protection. And because data shows waning immunity, these groups should get vaccinated now. 

The risk of getting infected with any virus, such as influenza or SARS-CoV-2, and experiencing severe illness increases with age. And for those living with a suppressed immune system, keeping up with COVID-19 vaccines will continue to protect these groups.

The Food and Drug Administration (FDA) says it will continue to evaluate data and information as it becomes available when considering the potential use of a second booster dose in other age groups.

Should I get a second booster now or wait?

If you are immunocompromised or over age 60, a second booster shot is highly recommended. While it’s still important to be vaccinated against the COVID-19 virus, it may not be necessary to receive a second booster shot right away for others. Because COVID-19 vaccine protection wanes, it could benefit an individual more to wait for another COVID-19 surge to maximize the benefits. 

If you were infected during a previous surge, such as Omicron, there is limited data about how long your antibody level is protective against COVID-19. 

Talk to your doctor about when to continue your vaccine series.

Is it too late to get a booster shot?

No, you can get a booster shot at least five months following the initial vaccine series for Pfizer-BioNTech and Moderna or two months after the Johnson & Johnson single-dose COVID-19 vaccine. A second booster is available for certain individuals at least four months after their first booster. According to the CDC, there is no known “expiration period” to get the booster. Evidence suggests a booster dose prevents more severe outcomes and can increase protection against symptomatic infection from COVID-19.

Which COVID-19 booster shot should I get?

The FDA has authorized three COVID-19 vaccine boosters and has determined it’s safe to get a vaccine booster or additional dose that is a different brand than your initial dose or doses. 

As of March 29, 2020, the CDC approved anyone who received the Johnson & Johnson COVID-19 vaccine or booster dose to get a booster dose of the Pfizer-BioNTech or Moderna mRNA COVID-19 vaccines. A second booster dose can be given four months after the first booster. If you get the Moderna booster, you’ll receive half of the original Moderna dose.

Can children get a booster shot?

Children ages 12 and older can get a COVID-19 booster shot. It’s not recommended for this age group to get a second booster unless they are moderately or severely immunocompromised. The Pfizer-BioNTech COVID-19 vaccine is the only vaccine authorized for children ages 12 and older.

Have there been any safety issues with additional COVID-19 vaccine doses?

To date, mRNA COVID-19 vaccines have proven to be safe and effective against SARS-CoV-2. Fatigue and pain at the injection site are the most commonly reported side effects. Serious side effects are rare but can occur.

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