Bivalent COVID vaccines are an updated version of the original COVID-19 vaccines. They are designed to offer broader protection against the evolving SARS-CoV-2 virus, adapting to changes in dominant viral strains.
What Bivalent Means for COVID Vaccines
The term “bivalent” indicates that the vaccine targets two different components of the SARS-CoV-2 virus. These vaccines include genetic material to prompt an immune response against the original SARS-CoV-2 strain, first identified in 2019. They also contain components designed to protect against more recent Omicron subvariants, such as BA.4 and BA.5. This dual targeting strategy aims to provide improved protection as the virus continues to change.
The rationale for developing bivalent vaccines stems from the virus’s continuous evolution. As new variants emerge, they can differ significantly from the original strain, potentially reducing the effectiveness of older vaccines. For example, the Omicron variant carries at least 60 mutations compared to the original SARS-CoV-2 strain. Regulatory bodies like the Food and Drug Administration (FDA) authorized these updated mRNA vaccines from Pfizer-BioNTech and Moderna to keep pace with these viral changes.
How Bivalent Vaccines Protect
Bivalent vaccines stimulate the body’s immune system to produce both antibodies and T-cells. These antibodies target the spike proteins of both the original SARS-CoV-2 strain and the targeted Omicron subvariants. T-cells also contribute to the immune response, helping to identify and eliminate infected cells.
The protection offered by bivalent vaccines aims to reduce the risk of symptomatic infection. They are also designed to significantly lower the chances of developing severe illness, requiring hospitalization, or leading to death from COVID-19. Studies have shown that a fourth dose of a bivalent vaccine can be more effective at preventing hospitalization compared to a fourth monovalent dose. For instance, one study indicated that bivalent booster vaccines were 37% more effective at preventing severe COVID-19 than original boosters.
Eligibility and Access
Bivalent COVID-19 vaccines are recommended as a booster dose for individuals who have completed their primary vaccination series. Everyone 6 months of age and older is eligible to receive a bivalent vaccine. Timing recommendations vary, but a bivalent booster is often suggested at least two months after the last monovalent dose.
An additional bivalent vaccine dose may be recommended for adults aged 65 years and older, or individuals aged 6 years and older with certain immunocompromising conditions. These updated vaccines are available at pharmacies, doctor’s offices, and public health clinics. The bivalent boosters are available at no cost.
Safety and Common Reactions
Bivalent COVID-19 vaccines undergo rigorous testing and monitoring, similar to previous COVID-19 vaccine formulations. Safety surveillance systems, such as v-safe and the Vaccine Adverse Event Reporting System (VAERS), continuously collect data on reported adverse events.
Common side effects are mild and temporary, resembling those experienced with earlier COVID-19 vaccines. These can include pain, redness, or swelling at the injection site, as well as systemic reactions like fatigue, headache, muscle aches, chills, and fever. While serious side effects are rare, they are closely monitored.