The updated XBB vaccine is the most recent formulation designed to address evolving public health needs. It offers a current approach to protection against the circulating virus. This development reflects continuous scientific advancements in vaccine technology.
Understanding the XBB Vaccine
The XBB vaccine is an updated formulation designed to target the Omicron XBB.1.5 subvariant and other closely related XBB lineages. SARS-CoV-2 constantly changes through mutations, leading to new variants that can alter how effectively previous vaccines or natural immunity protect. This vaccine replaces earlier bivalent vaccines, which targeted both the original SARS-CoV-2 strain and earlier Omicron subvariants. The updated vaccine is a monovalent formulation, focusing on a single, currently prevalent lineage to provide a more tailored immune response, as the original SARS-CoV-2 strain is no longer widely circulating.
Eligibility and Protection
The updated XBB vaccine is recommended for most individuals aged 6 months and older, irrespective of previous vaccination history. Individuals aged 12 years and older generally need one dose. Children aged 6 months to 4 years may require one or two doses depending on prior vaccination status, while those aged 5 to 11 years generally need one dose. People aged 65 years and older may consider two doses, usually administered a few months apart.
This vaccine offers protection against severe outcomes, including hospitalization and death from current circulating variants. Studies indicate the updated monovalent XBB.1.5 vaccine provided about 54% protection against symptomatic SARS-CoV-2 infection among recently vaccinated individuals. Against COVID-19-associated hospitalization, vaccine effectiveness in immunocompetent adults was approximately 53% in the first two months after vaccination. For older adults aged 65 and above, effectiveness against hospitalization was around 50-54% and against COVID-19-related death was about 48-58%.
Protection from a combination of vaccination and prior infection, often called “hybrid immunity,” offers broader defense against subsequent infections. This combined immunity is more effective at protecting against severe cases and preventing hospitalization than immunity from infection alone. While protection can wane over time, particularly against less severe disease, the vaccine helps reduce the risk of serious health consequences.
Safety Profile
The XBB vaccine can cause temporary side effects. Common reactions include pain, redness, or swelling at the injection site. Other common systemic side effects are fatigue, headache, muscle pain, joint pain, chills, and fever. These reactions typically develop within a day or two and usually resolve on their own within a few days.
Health authorities rigorously monitor safety to track any potential adverse events. Serious adverse events following vaccination are uncommon. Anaphylaxis, a severe allergic reaction, is rare, with an incidence of approximately 5 cases per million doses administered. Cases of heart inflammation, such as myocarditis and pericarditis, have been reported but are also rare, with most individuals experiencing mild symptoms and recovering well.