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How Effective are Boosters against XBB.1.5 and Other COVID Variants?


By Holadoctor

New scientific studies have confirmed the importance of using bivalent COVID boosters to prevent severe disease and possible death caused by this infection. This research has shown that the updated vaccines do act against the new coronavirus variants, such as XBB.1.5.

Given the strong evidence, the U.S. Food and Drug Administration (FDA) is finally considering a strategy that has long been under discussion: having seasonal COVID vaccines that, like the influenza vaccine, are reformulated every season to work against new strains.

The FDA’s work is based on scientific studies and the analysis of the U.S. Centers for Disease Control and Prevention (CDC). An analysis of data from national pharmacy testing found that a bivalent mRNA booster dose provided additional protection against symptomatic infection with the XBB/XBB.1.5 variants for at least the first three months after vaccination in people who had previously received two, three, or four monovalent vaccines doses.

The CDC emphasizes that all people, of all ages, should remain up-to-date with the recommended COVID-19 vaccines and should receive a bivalent booster dose each time they become eligible again.

Although the CDC analysis did not take into account previous COVID-19 infections, which also confer immunity, the updated boosters were found to reduce the risk of symptomatic infection by half for most adults, and by one third for adults aged 65 and older. 

An earlier study found that bivalent boosters provided substantial additional protection against severe omicron infection in people who had previously been vaccinated or boosted, although the effectiveness decreased over time. The effectiveness of bivalent boosters was greater than that of monovalent boosters. 

The difference between the effectiveness of the two vaccines was overwhelming. For people aged 12 or older who received the monovalent vaccine, protection against severe disease and hospitalization was 25%, while the effectiveness of the bivalent vaccine was 58.7%.

In clinical settings, vaccine effectiveness against severe disease and death was 24.9% for the monovalent vaccine and 61.8% for the bivalent booster.

By mid-2022, 70% of the population of Latin America and the Caribbean had been immunized with the initial two doses of the COVID vaccine. Vaccination intention (the measure of vaccine acceptance and the decision to receive the vaccine, including boosters) has remained high in the general population in the region, but it has been consistently low among older adults and pregnant women.

In total, 30 different vaccines are used in different vaccination campaigns worldwide; the most effective in preventing infection are those produced with mRNA technology.

Globalization of a seasonal COVID-19 vaccine is the next public health goal.

Worldwide, nearly 1.9 million new cases of COVID-19, and more than 12,000 deaths, were reported in the week of January 16-22, 2023, according to data from the World Health Organization (WHO).

NOTE: This story was produced using content from the original study or report and from other medical research, as well as health and public health sources, highlighted in related links throughout the article.