For most people, the COVID-19 vaccine provides a high degree of protection for at least several months. Booster shots help them retain immunity from the virus.

As of November 2022, more than 80% of the United States population has received full vaccination with a primary series of COVID-19 vaccines and boosters. For those over 65 years, this vaccination rate is 95%.

Although experts are confident that vaccines are effective, they are unsure exactly how long they provide protection. Figures vary depending on the type of vaccine a person gets, but most research indicates that immunity lasts around 4 months. Therefore, boosters are essential for adequate protection.

Read on to learn about the protection each vaccine type provides, when boosters are necessary, and more.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub for the most recent information on the COVID-19 pandemic.

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Research is ongoing to determine how long COVID-19 vaccine immunity lasts.

Data from early in the pandemic found that individuals who received vaccination with Pfizer or Moderna COVID-19 vaccines had immunity for around 4 months after booster doses. However, the amount of protection varies depending on a person and the vaccine they receive, so this number is a rough estimate.

Four COVID-19 vaccines have approval or authorization from the Food and Drug Administration (FDA) for use:

The following explains how each vaccine works and how long each protects against COVID-19.

Pfizer-BioNTech

The Pfizer-BioNTech vaccine is a newer type that uses mRNA from SARS-CoV-2, the virus that causes COVID-19, to create immunity in the body. Although mRNA vaccines are a new technology, researchers have studied them for many years and used them for seasonal flu and rabies.

Doctors deliver the vaccine in a primary series of two doses spaced 3–8 weeks apart. It offers full protection 2 weeks after the second dose.

Clinical trials show that the Pfizer vaccine is at least 91% effective in preventing symptomatic COVID infections for 6 months and 100% effective in preventing severe diseases requiring hospitalization. Additionally, a 2021 research review found that Pfizer and Moderna were better at preventing symptomatic disease compared with other vaccines.

Moderna

The Moderna vaccine is another mRNA vaccine that healthcare professionals administer in two initial doses. A person has full protection 2 weeks after the second dose, but they benefit from some level of protection sooner.

In the first 2 weeks, the vaccine is 50.8% effective. This increases to 94.5% two weeks after the second dose.

A person should develop strong antibody protection for about 6 months following the initial two-dose course of the Moderna vaccine. Over time, their protection against the virus will gradually decline. They then require a booster shot to maintain long-term levels of antibodies in the body.

Novavax

The Novavax vaccine is a protein subunit vaccine. It uses pieces of the virus’s proteins to create immunity, rather than using a deactivated virus or mRNA. Additionally, it contains a substance called the Matrix-M adjuvant that helps create a stronger immune response.

A person requires a primary series of two shots 3–8 weeks apart. People have full protection 2–3 after their second dose. In Novavax’s trials of more than 15,000 people, the vaccine was around 90% effective against COVID-19.

Johnson & Johnson

The Johnson & Johnson vaccine is a single-dose vaccine. Protection occurs 2 weeks after vaccination.

Research shows that after 2 weeks, the vaccine is 66.9% effective in preventing moderate to severe critical COVID-19 disease. This increases to 85.4% after 28 days. It is also 100% effective in preventing hospitalizations.

At present, experts are unsure how long immunity from the Johnson & Johnson vaccine lasts. However, the Centers for Disease Control and Prevention (CDC) now recommend that people receive the Pfizer and Moderna vaccines instead, as they are known to be more effective.

Yes, people require booster shots for all types of COVID-19 vaccines. They help maintain immunity against the disease.

The length of time a person has protection from the initial vaccine series differs. However, the CDC recommends people have a Pfizer-BioNTech or Modernabooster shot at least 2 months after a person’s second primary series dose or last booster.

Hybrid immunity refers to immunity from a combination of vaccination and previous infection with SARS-CoV-2.

When a person has hybrid immunity, they may have a higher level of protection against COVID-19 than when they have vaccine-induced immunity or natural immunity alone. Some research has found that hybrid immunity can protect a person against COVID-19 for more than a year.

COVID-19 vaccines are effective in preventing symptomatic disease, severe disease, and hospitalization. People require a primary series of shots and boosters for full protection.

Data suggests that fully vaccinated people benefit from several months of immunity. With mRNA vaccines, this may extend to around 6 months. Hybrid immunity, which people develop from both vaccination and previous infection with SARS-CoV-2, may offer longer-lasting protection.