Fonte: FirstWord Pharma
Leia a notícia como publicada originalmente pelo portal FirstWord:
Real-world study findings released by the US Centers for Disease Control and Prevention (CDC) found that bivalent COVID-19 booster shots targeting the Omicron strain provided “significant additional protection” against symptomatic infection, according to the agency. “These are the first published estimates of [vaccine effectiveness] for newly authorised bivalent mRNA booster vaccines,” the CDC said, noting that “in this study, relative benefits of a bivalent booster compared with monovalent vaccine doses alone increased with time since receipt of last monovalent dose.”
However, results of the analysis also showed that the increase in protection was less than 50% across almost all adult age groups, compared to unvaccinated individuals.
Researchers sought to evaluate the effectiveness of Omicron BA.4/BA.5-containing mRNA shots against symptomatic SARS-CoV-2 infection using data from a national SARS-CoV-2 testing programme. The analysis included just under 361,000 COVID-19 tests performed in adults at nearly 10,000 pharmacies in the US from September 14 to November 11, when the BA.4 and BA.5 strains were dominant.
Compared with unvaccinated people, adults ages 18 to 49 years old who had gotten a bivalent booster dose were 43% less likely to fall ill with a COVID-19 infection. People ages 50 to 64 were 28% less likely, while those ages 65 and older were 22% less likely to get sick with COVID-19 than the unvaccinated group. For seniors, the booster was 19% effective at preventing symptomatic illness when administered as their fourth dose, compared to the unvaccinated, and 23% effective when given as their fifth dose.
Meanwhile, relative vaccine effectiveness showed what added protection people might expect on top of whatever they had left after previous doses. The CDC said that at two to three months after a person’s last vaccine dose, the Omicron boosters added an average of 30% protection for those who were in the 18-to-49 aged group, 31% more protection if they were between 50 and 64 years old, and 28% more protection among those 65 or older. If the gap was at least eight months since their last dose, then protection was higher, reaching 56% for those aged 18-to-49 years old, 48% for those in the 50-to-64 group, and 43% for those aged 65-plus.
“It’s better than nothing,” remarked Andrew Pekosz, a virologist at Johns Hopkins University. “Certainly, it doesn’t sort of show that the protection is incredibly high against infection,” he said, but “I would expect that you would then see even greater protection from hospitalisation or death.” Paul Offit, a member of the FDA’s vaccine advisory committee, suggested that the “goal is protecting against severe disease,” given that efficacy against mild illness “just isn’t that good in the Omicron…era.”
However, Celine Gounder, a senior public health fellow at the Kaiser Family Foundation, noted that even if the reduction in risk is relatively modest at the individual level, that could still translate to a significant positive impact across an entire population. “If you can reduce risk among the elderly by even 30%, even 20%, that is significant when 90% of the COVID deaths are occurring in that group,” Gounder said.
Meanwhile, it remains unclear how the boosters will perform against emerging Omicron subvariants, such as BQ.1 and BQ.1.1, which have since become dominant in the US. Pfizer/BioNTech and Moderna recently said early clinical trial data indicate that their respective bivalent boosters induce an immune response against these relatively new strains as well.
