Kate Colby, MPH, is a public health expert with extensive experience in infectious disease epidemiology.
In August 2024, the U.S. Food and Drug Administration (FDA) approved an updated mRNA COVID-19 vaccine to target circulating variants, including the Omicron variant KP.2 strain of SARS-CoV-2.
The Centers for Disease Control and Prevention (CDC) reported in September 2024 that SARS-CoV-2 Omicron variants KP.2, KP.2.3, KP.3, and KP.3.1.1, plus LB.1 had a high prevalence in the United States. Variants occur because sometimes when viruses infect cells and reproduce, errors or mutations happen.
The CDC recommends everyone ages 6 months and older get a 2024-2025 COVID-19 booster vaccine. Staying up-to-date can help protect you as new COVID strains emerge. Booster vaccines are recommended because the COVID-19 vaccine protection, like many other vaccines, decreases over time.
What Are COVID-19 Variants?
After the outbreak of COVID-19 in 2019, the virus began to evolve, forming what are called "variants." The COVID-19 variants with higher prevalence included Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and Omicron (B.1.1.529).
On September 17, 2024, the CDC reported that the Omicron variants KP.2, KP.2.3, KP.3, and KP.3.1.1 had caused the most infections in the U.S. You might hear these subvariants referred to as "FLiRT" strains.
Why Do COVID Vaccines Need To Be Updated?
"The problem we have with Omicron variants is that it's a smarter virus. The antibodies that you made for Omicron way back in December don't function very well to protect you," Sharon Nachman, MD, the division chief of pediatric infectious disease at Stony Brook Medicine, told Health in 2022.
While antibodies from vaccines also provide limited protection, they may provide better protection than the antibodies your body produces after infection. This is because vaccines produce more long-lasting antibodies.
What Variants Does the Updated Vaccine Protect Against?
The FDA and the CDC monitor which variants cause the most infections each year. It's important to stay current on your COVID vaccinations because they are designed to help protect against newly developing variants.
The 2024-2025 updated mRNA vaccine contains a component corresponding to the Omicron variant KP.2 strain of SARS-CoV-2. Researchers determined this variant had the potential to be significantly infectious.
How Long Are Updated COVID Vaccines Effective?
COVID vaccines remain the most effective way to avoid becoming seriously ill if you do get COVID. People who have an updated vaccination tend to experience milder symptoms and a lower risk of needing to be hospitalized.
Like the flu shot, COVID vaccines lose effectiveness over time. That's why it's important to stay up-to-date on vaccinations. You can visit the CDC website for updated recommendations.
What Is the Future of COVID Vaccines?
Updating and reformulating boosters and vaccines is one approach to addressing the mutations. A theorized effective and long-lasting solution might include developing a universal coronavirus vaccine that targets regions of the virus that do not mutate as much.
"The holy grail would be to make an agnostic vaccine that doesn't care about multiple variants. We would develop a vaccine that makes antibodies to the non-variable region, but it's still protective against people getting that virus attached to their cells," Dr. Nachman said.
Until then, it's important to stay up-to-date on COVID vaccines.
A Quick Review
In August 2024, the FDA approved an updated mRNA COVID-19 vaccine to target circulating variants, including the Omicron variant KP.2 strain. When the viruses that cause COVID spread and reproduce, variants can evolve from mutations. COVID vaccines are updated to try to protect against evolving variants that are causing infections around the world.
The CDC recommends everyone ages 6 months and older get a 2024-2025 COVID-19 booster vaccine. Variants are continuously being monitored and identified to inform researchers in what vaccines are developed. Being vaccinated against COVID is still the most effective way to prevent serious illness.