Booster shots with updated Covid-19 vaccines from Pfizer/BioNTech and Moderna helped prevent symptomatic infections against new subvariants related to the XBB variant, providing new evidence of how the vaccines work against these rapidly spreading strains, they said. US authorities this Wednesday (25).
“Today we have additional evidence to show that these updated vaccines are protecting people against the newer variants of Covid-19,” said Brendan Jackson, head of the COVID-19 response at the US Centers for Disease Control and Prevention (CDC). , told reporters.
The updated boosters target the BA.4 and BA.5 omicron variants of the Sars-CoV-2 virus, which are no longer dominant. The now dominant XBB-related subvariants are derived from the BA.2 version of omicron.
Laboratory studies suggested that the vaccine’s protection was lower against the XBB variants compared to earlier variants, raising questions about how well the vaccines would work against these growing strains of the virus, Jackson said.
For the study, the researchers reviewed cases of Covid-19 from December 1 to January 13, during which time the US circulation of XBB and XBB.1.5 increased. Research showed that the updated vaccine helped prevent disease in approximately half of people who had received two to four doses of the original vaccine, the CDC said.
The CDC said the updated vaccine worked similarly against BA.5-related infections and XBB/XBB.1.5-related infections. The vaccine was 52% effective in preventing infections with BA.5 and 48% against XBB/XBB.1.5 among those aged between 18 and 49 years. Efficacy dropped to 37% against BA.5 and 43% against XBB/XBB.1.5 among those aged 65 and over.
While that didn’t show up in the study, Jackson said data to be released later on Wednesday show that the updated vaccine reduced the risk of death from Covid-19 by more than twice compared with vaccinated people who didn’t get the booster. updated. The updated vaccine also reduced the risk of dying from the disease by nearly 13 times in unvaccinated people.
Study author Ruth Link-Gelles of the CDC said that, overall, vaccines reduce the risk of symptomatic infection in about half of a population, but individuals see a different benefit based on their risk factors.
Link-Gelles said the estimates are for symptomatic infections, which the CDC has defined as one or more symptoms of Covid-19. Given the findings, the CDC urged people to stay current with recommended vaccines against the disease.
XBB.1.5 was estimated to account for nearly half of US cases in the week ended Jan. 21, government data showed.
The CDC analysis comes ahead of a meeting this Thursday (26), in which external experts from the US Food and Drug Administration (FDA) are expected to discuss whether and how the United States should offer the Covid vaccine annually.
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