How Long Will COVID-19 Vaccine-Induced Immunity Last?

As of June 2022, more than 66% of the United States population had been fully vaccinated with one of the three COVID-19 vaccines authorized by the Food and Drug Administration (FDA): Pfizer-BioNTech, Moderna, and Johnson & Johnson.

Nearly 105 million people, or about 47% of those fully vaccinated, have received a booster dose. Yet it remains unknown how long vaccine immunity against COVID-19 will last, or how the vaccines would perform against B.1.1.529 (Omicron) and other potential variants of the virus in the future.

This article explores research on the vaccines and what is known about the immunity they provide. It will help you to know more about each specific vaccine and how often you will need to get them.

Like most vaccines, the COVID-19 vaccines work in more than one way to prevent infection. The first involves the production of antibodies.

Your body uses antibodies to fight off infection, but not as easily when it has never seen a novel, or new, virus. Because COVID-19 was a new virus, human bodies had not developed an antibody defense for it. The vaccines help it to achieve that.

The second way the vaccines work is to help the body develop responses in what are called memory B cells and T cells. These are immune cells that store information for future reference.

However, immunity does wane. Your individual response and other factors contribute to this loss of protection. Like human memory, cellular memory is short. Booster shots help to "remind" it to respond to a virus or other pathogen. Here's how each of the current vaccines work.

Pfizer-BioNTech Vaccine

Pfizer-BioNTech is an mRNA vaccine, based on a newer approach to making vaccines. It relies on the power of nucleic acids found in genetic material, but not the DNA that is uniquely yours. Here's what is known about how long it will work to offer immunity.

Pfizer's vaccine, also known as Comirnaty, was authorized for emergency use in the U.S. in December 2020. In August 2021, it received full approval from the FDA for use in individuals ages 16 and older. It is currently authorized for emergency use in children and adolescents 6 months to 15 years of age.

When Does It Start Working

The Pfizer vaccine is given in two doses scheduled three weeks apart. However, an eight-week interval may be optimal for some people ages 12 and over—particularly for males ages 12 to 39 years. According to the Centers for Disease Control and Prevention (CDC), an interval longer than four weeks may help reduce the risk of myocarditis associated with the mRNA COVID-19 vaccines.

These doses are given as injections and offer full protection two weeks after the second dose, the CDC says. The data suggest that after the first dose, some immune response is present in about two weeks.

How Long Will Immunity Last?

According to Pfizer, initial results based on Phase 3 clinical trials in adults found the vaccine was:

• 100% effective in preventing severe disease (as defined by the CDC)
• 95% effective in preventing severe disease (as defined by the FDA)
• 91% effective in providing immunity against COVID-19 for six months

A November 2021 update focused on how effective the vaccine was in people ages 12 to 15. These results showed the vaccine was 100% effective against COVID-19.

Further research on the Pfizer vaccine, also known as Comirnaty, supports its effectiveness. A November 2021 research review of studies on nine different COVID-19 vaccines developed around the world found that overall, the Pfizer and Moderna vaccines performed better than alternatives in preventing symptomatic disease.

Booster Shots

In November 2021, the FDA approved a single booster shot of the Pfizer COVID-19 vaccine for people aged 18 and older. The FDA later expanded that authorization to include children and adolescents ages 5 to 17 who completed their initial vaccination series at least five months prior.

A Pfizer booster is available to any eligible person, regardless of which vaccine they had before.

This means that you can use a different vaccine for your booster shot than the original one was. In fact, a number of studies suggest that this mixed approach may offer even better protection. The CDC, however, cautions against mixing vaccines when getting your initial two-dose vaccination.

On March 29, the FDA authorized additional mRNA booster doses for certain higher-risk individuals. A second booster dose is now recommended for persons 12 years and older with certain kinds of immunocompromise and all adults 50 and older who have received an initial booster dose at least four months prior.

Moderna Vaccines

The Moderna vaccine, also known as Spikevax, has been FDA approved for use in the U.S. since January 2022 for the prevention of COVID-19 in individuals 18 years of age and older. Prior to this approval, it had been authorized for emergency use in the U.S. since December 2020. In June 2022 the FDA authorized emergency use of the vaccine in individuals 6 months through 17 years of age. Like Pfizer, it is an mRNA vaccine but there are a few differences.

When Does It Start Working

The Moderna vaccine also is given in two doses. Both are needed to be considered fully vaccinated. People who receive this vaccine need to schedule their second dose four weeks after the first—and no sooner.

As with the Pfizer vaccine, the CDC states that an eight-week interval between doses may be optimal for certain people to reduce the risk of myocarditis.

Full protection is achieved two weeks after the second dose, but some protection occurs earlier. A document filed with the FDA shows overall efficacy of 50.8% between days one to 14. That rises to 92.1% after 14 days when you've had one dose but are still waiting for the other.

How Long Will Immunity Last?

Correspondence in The New England Journal of Medicine (NEJM) states that Moderna was found to offer strong antibody protection for at least six months following the second dose.

Booster Shots

On November 19, 2021, the FDA approved a single booster shot of the Moderna COVID-19 vaccine for those aged 18 and older. It is available to those fully vaccinated with any FDA-authorized or approved COVID-19 vaccine.

A second mRNA booster dose is now authorized for people 12 years and older with certain kinds of immunocompromise and all adults 50 and older who have received an initial booster at least four months previously.

Johnson & Johnson Vaccines

Research on the single-dose COVID-19 vaccine made by Johnson & Johnson, as well as many others, is ongoing. Support for the use of the Johnson & Johnson vaccine also has changed over time. Here's what is known so far.

When Does It Start Working?

Protection is achieved two weeks after the single-dose Johnson & Johnson vaccine.

The initial data from the ENSEMBLE clinical trials of the drug found it was:

• 66.9% effective in preventing moderate to severe–critical COVID-19 cases after 14 days
• 66.1% effective in preventing moderate to severe–critical COVID-19 cases after 28 days
• 85.4% effective in preventing severe COVID-19 cases after 28 days
• 100% effective in keeping people with severe COVID-19 out of the hospital

In December 2021, however, the CDC announced that while this COVID-19 vaccine will remain available, the Pfizer and Moderna vaccines would be preferred.

This decision followed a recommendation from the Advisory Committee on Immunization Practices (ACIP) for the prevention of COVID-19. It was made in part because of the additional risk of blood clots associated with the Johnson & Johnson vaccine.

That risk was noted during a previous April 2021 pause in using this vaccine, but additional cases were recorded later. The CDC decision on Johnson & Johnson follows similar rulings about the vaccine made in other countries.

How Long Will Immunity Last

The short answer is that no one is really sure how long immunity from the Johnson & Johnson virus will last. The CDC decision to discourage use of the Johnson & Johnson vaccine, in favor of the other two mRNA vaccines, also was based on the evidence for how effective it is.

Booster Shots

People who are over 18 years old are eligible for a booster at least two months after getting the single Johnson & Johnson COVID-19 shot.

You can choose a different vaccine, either the Pfizer or Moderna, for the booster. It doesn't have to be the same one and they can be mixed.

Effectiveness Against New Strains

The COVID-19 virus has changed over time due to mutations that result in a different strain of the virus. This is common for viruses, but some changes have greater impact than others. They may spread more rapidly, cause more or less serious illness, or fail to respond to the existing vaccines.

The CDC will classify some strains as a "variant of concern" when they have the potential for this greater impact. As of December 2021, there were two variants of concern in the U.S. They were:

• Omicron (B.1.1.529) first identified in Botswana and South Africa
  
• Delta (B.1.617.2) first identified in India

Omicron and Vaccines

Because the Omicron variant was newly emerging and spreading quickly, there is little data to support a conclusion about how vaccines will provide immunity. In a December 2021 update, the CDC said it fully expected breakthrough infections even among the fully vaccinated.

Early evidence suggests that vaccinated people can still spread the Omicron variant. However, the existing vaccines were still expected to protect against serious illness and death.

On the other hand, a preprint study released in December 2021, which was not yet peer-reviewed, found the Johnson & Johnson vaccine offered virtually no protection against the Omicron strain of the COVID-19 virus. The data raise additional concerns about how this vaccine can protect against Omicron and other emerging strains of the virus in the future.

Delta and Vaccines

The Delta variant spreads more easily than the original COVID-19 virus and other strains that have emerged since. It also may cause more severe illness and death.

As with Omicron, breakthrough infections are expected in fully vaccinated people but vaccines remain effective against more serious outcomes. The CDC says that all of the FDA-approved or authorized vaccines will continue to be effective against severe illness and death.

Previous studies suggest that all three authorized vaccines offer protection from these variants, but research is ongoing to try to understand the level of protection you can expect.

In many cases, the science is focused on creating new vaccines that target specific strains as they evolve. Pfizer, for example, was already working on this. The process would work much the way an annual flu shot does.

A November 2021 review of the three existing vaccines summarized how well they perform against these new strains of the COVID-19 virus. These findings are included below:

Pfizer-BioNTech

The vaccine was found to be 88% effective at providing protection against the Delta variant. It also was effective against some variants that preceded Delta, such as the B.1.351 variant.

A Canadian study further found the Pfizer vaccine reduced the risk of hospitalization. Some researchers have found, however, that immunity is weakened in older people who are vaccinated.

Moderna

The vaccine was found to be 88% effective at providing protection against the Delta variant, as well as several that came before it, such as the P.1 variant first found in Brazil.

Researchers found, however, that the immunity waned over time, suggesting the need for boosters or annual vaccinations in the future.

Johnson & Johnson

A Johnson & Johnson clinical trial found that the overall efficacy in its South Africa trial was lower (64%) than in other trial locations, such as the United States (72%). However, its protection against severe disease included the B.1.351 variant and some other variants.

Summary

The short answer to how long your COVID-19 vaccine will protect you is that no one knows for sure yet. The FDA is clear that there is not yet enough data to definitively answer the question.

But two years after the pandemic started, there has been much progress. The three vaccines that are authorized for use in the U.S. (Pfizer, Moderna, and Johnson & Johnson) continue to protect people from becoming seriously ill in the hospital or dying from the disease.

Just as the virus changes over time, so does the global response to it. New strains like Omicron and Delta present a challenge as to whether the vaccines will work. New research results may suggest a vaccine is less safe or effective. That's likely to be the case for the foreseeable future.

A Word From Verywell

The COVID-19 pandemic has meant a stressful time for everyone. That's not been made easier by the ever-shifting information about vaccines and COVID variants. If you're still not sure about the vaccines, consider the CDC advice: Any vaccine is better than none at all.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.