Updated June 7, 2022

On March 29, the Food and Drug Administration (FDA) authorized an additional Pfizer-BioNTech or Moderna mRNA booster shot for those who are 50 years old and older and younger people with compromised immune systems. The Centers for Disease Control and Prevention (CDC) then added this second booster to its coronavirus vaccine recommendations.

The second booster can be given as early as four months after the first booster. Individuals aged 12-17 years can only get a Pfizer booster, while those 18 years old and older can get either a Pfizer or Moderna booster. 

The reason for the recommendation is the continued emergence of the highly contagious BA.2 sub-variant of Omicron, which was the cause of 85% of all COVID-19 cases in the United States on April 12, 2022. The recommendation was made despite the fact that the SARS-CoV-2 BA.2 variant is a milder disease — like the BA.1 and BA.1.1 variants and the number of new COVID deaths continues to drop. 

There are three additional reasons why the FDA and CDC made this recommendation:

1. Many countries experienced increased COVID-19 BA.2 variant infection rates before the U.S.  Five weeks later the number of cases and hospitalizations is increasing again in the U.S., primarily due to Omicron’s BA.2 subvariant called BA.2.12.1, which is 25% more contagious than BA.2.
2. A seasonal increase in cases is expected this fall.
3. The reduction of protective measure usage, such as face masks and social distancing, and reduced testing may also increase the risk of a COVID infection surge.

While the second booster dose of an mRNA COVID-19 vaccine is not associated with new safety concerns and it improves protection against severe COVID-19, protection from COVID illness is short-lived — about eight weeks. 

Coronavirus cases have risen in major cities. While hospitalizations have not, it is not a reason to defer boosters. Since there are still so many susceptible to severe illness, any drop in the number of cases is significant.

Rating the Need for a Second Booster

Now that the recommendation has been made, who should consider getting a booster right away if it has been more than four months since their last one and who can wait? It all comes down to the state of your immune system: the weaker your immune system, the greater your need for a second booster. There are a number levels of need.

At the top of the list are those who are immunocompromised, either from an underlying condition or from treatment of a condition, such as an organ transplant, cancer, or autoimmune disease. These people should get a booster as soon as possible and may even qualify for an additional booster at a later date.

Those who have had only Johnson & Johnson shots as primary and booster doses should get an mRNA booster.

As we age, our immune systems weaken. This effect on the immune system becomes relevant for seniors 65 years old and older. While CDC Director Rochelle Walensky recommends that seniors get a second booster, other experts think that it is not so straightforward and that other factors need to be taken into account.

• Because the weakening of the immune system is gradual, most younger seniors still have adequate immune system function and can defer their second booster, while older seniors should not. Unfortunately, there is no specific age cutoff for this distinction.
• Timing of the second booster should come into play, given the short-lived protection against COVID disease. Now that  there is a spike in COVID cases as a result of the increase in the COVID BA.2 variant and Omicron’s BA.2 subvariant called BA.2.12.1, the booster becomes more important. This is especially true since immunization protects against the new variant better than an infection with a previous variant. This would have a greater impact on the spike than spreading them out and having more people susceptible to infection when the spike occurs.
• A longer interval between booster shots produces a stronger immune system response and more cross-reactive defense.
• Other vaccines targeting newer variants, such as the BA.4 and BA.5 variants currently affecting South Africa, may become available before many may need a second booster.

People aged 50-64 years with chronic illnesses such as heart disease, lung conditions, reduced kidney function, diabetes, or obesity are more likely to have weaker immune systems and should get a second booster at some point.

Those who have had a recent COVID-19 infection — especially those who have already had a booster — should have a higher immunity and can consider deferring the second booster, but the recent increases make this riskier.

There are currently no recommendations for those less than 50 years old.

For now, it is evident that all adults 50 years old and older who are immunocompromised and elderly adults with weak immune systems should get a second COVID booster as soon as possible. A second booster is recommended for those aged 50-64 years with chronic illness and younger seniors, but the jury is still out on the timing.

Unfortunately, many of those who qualify for boosters are not getting them. In fact, 82.1 million doses of COVID vaccine were discarded from December 2020 mid-May 2022.

An expert panel of independent advisers met on April 6, 2022 to discuss the future of COVID boosters. The panel was able to identify many issues that need to be addressed, but was unable to offer any solutions. These issues include:

• Given how quickly COVID variants develop, how often it is practical to give boosters, especially those at highest risk;
• The importance and practicality of developing multivalent vaccines to current and future COVID variants that would offer more protection than the currently available vaccines;
• Developing better ways to assess vaccine effectiveness than hospitalization rates and death rates, such as immunological markers or community transmission; and
• What pattern recurrent COVID-19 epidemics will fall into.

Visit COVID Data Tracker for up-to-date information about all aspects of COVID disease and Covid.gov for information about local COVID resources.