![]() ![]() 3 Decreasing antibody responses may be accompanied by the development of long-lived SARS-CoV-2–specific B cells or other cellular protective mechanisms that offer durable protection against more severe disease outcomes. Booster doses are thought to protect via mechanisms that include enhanced humoral responses but also through generation and expansion of T-cell memory, broadening epitope recognition and perhaps other immunologic parameters that were not measured. ![]() Individuals with prior SARS-CoV-2 infection were excluded, limiting generalizability as the global prevalence of prior infection increases. It was observational, and the small sample of 48 participants was self-selected. This study had some important limitations. Sex, age, time since vaccination (which varied only minimally), and presence of comorbid conditions were not associated with postvaccination IgG titres, providing limited evidence that boosters are suitable for most people. The results show a significant but transient increase in IgG titers after the third dose, decreasing approximately 10-fold after 5 months titers were then restored immediately after a fourth dose. ![]() Conducted in Israel, a country that has recommended fourth doses of the Pfizer-BioNTech BNT162b2 vaccine to all adults aged 60 years or older since January 2022, this observational study compared immune response-measured as anti–spike protein immunoglobulin G (IgG) antibody titers-before and after third and fourth vaccine doses, thereby providing information on the magnitude and duration of the immune boost. The optimal timing of booster vaccinations is therefore a priority unanswered question for vaccine developers and policy makers alike, aiming to develop and implement vaccination programs that protect people most efficiently as we transition to endemic COVID-19.Įliakim-Raz and colleagues 2 report on a study that aims to help answer this question. Booster doses restore protection against infection back to higher levels and incrementally improve protection against severe COVID-19, but frequent booster vaccinations are expensive, inconvenient, and possibly inefficient. 1 In a bid to preserve effectiveness in the midst of emerging variants and waning immunity, third and even fourth “booster” dose vaccinations have been implemented in some countries. Subsequently, gradual reductions in observed vaccine-derived protection, particularly against milder end points of COVID-19, were observed approximately 5 to 6 months after the end of the vaccine primary series. After effective vaccines became available, long lines formed in many countries of residents seeking their first and second doses, which protected the most vulnerable members of society from the most severe disease outcomes and thereby allowed social and professional activities to restart more freely without fear of those interactions causing unacceptable levels of societal harm. Visit the CDC’s COVID-19 vaccine and booster page for more details.Many people may wish to forget the level of societal and health care disruption, fear, and illness caused by SARS-CoV-2 before vaccines were available, when the only tools available to protect ourselves were incompatible with the lives we wished to lead. However, the monovalent vaccines will remain available for the primary vaccine series in all patients and for booster doses in patients younger than 5 years old. ![]() The monovalent COVID-19 vaccines will no longer be available for booster doses in patients over the age of 5. The bivalent vaccines, which offer better protection against COVID-19 caused by the omicron variant than the earlier, monovalent vaccines, have been authorized for use as a single booster dose administered at least two months after primary or booster vaccination. The CDC recommends a bivalent (containing components of both the original strain of the SARS-CoV-2 virus and the omicron variant of the virus) COVID-19 booster for people ages 5 years and older. Recommendations for use of a bivalent Pfizer-BioNTech booster dose in people ages 5–11 years.Recommendations for use of a bivalent Moderna booster dose in people ages 6–17 years.12, 2022, the new COVID-19 booster recommendations for people ages 5 years and older is to receive 1 bivalent mRNA booster after completion of a monovalent primary series or previously received monovalent booster dose(s) these recommendations replace all prior booster recommendations for this age group. ![]()
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