The protection afforded by a third dose of the vaccine to prevent symptomatic virus infection caused by the omicron variant regresses ten weeks after vaccination, according to an analysis by the UK’s Health Safety Agency. The analysis, based on data from 56,066 infections of the new variant, indicates that a booster dose of Moderna’s vaccine provides longer-lasting immunity than the third dose with Pfizer.
A study from Columbia University in New York was published yesterday in the journal temper nature He confirms, by the same token, that subjects vaccinated with a third dose of Moderna had more neutralizing antibodies against omicron than subjects vaccinated with Pfizer. The results indicate that if the first two doses of mRNA vaccines such as the Pfizer and Moderna vaccines are, protection is higher than if the initial regimen was with adenovirus vaccines such as the AstraZeneca and Janssen vaccines. In all cases, as well as after the third doses, protection from Omicron is less than that against the original variant of SARS-CoV-2.
The new data reinforces the idea that it would be appropriate to manufacture specific vaccines against Omicron
“Even a third dose may not adequately protect against oomicron infection. It would be appropriate to develop specific vaccines against this variant,” David Hu, the study’s lead author, says by email. Despite this decrease in efficacy against infection, he argues is that “booster vaccination is recommended to protect against disease”.
Based on UK data, immunity after the third dose is highly dependent on the combination of vaccines received. If the initial regimen with the Pfizer vaccine, a third dose also with Pfizer achieves 70% efficacy in preventing symptomatic infections in the first weeks after the booster dose. That is, out of every 100 people infected with coronavirus, 70 are avoided but 30 occur, which indicates that even people who have been vaccinated with a third dose should maintain prevention measures. However, after ten weeks of a booster dose with Pfizer, the effectiveness in preventing symptomatic infections drops to 45%.
People who have been vaccinated with the third dose can become infected, so it is advisable to maintain preventive measures
In the case of the initial regimen with Pfizer and the booster dose with Moderna, the initial protection is about 75% and remains stable above 70% after nine weeks. There is no data yet as to how long this protection will be maintained.
If the initial treatment regimen is with AstraZeneca, the initial protection after the third dose is about 60%. After nine weeks, the rate drops to 45% if Moderna was received as a booster and to 35% if Pfizer was received.
Currently, there are no data to evaluate the effectiveness of other vaccine combinations – eg, whether the initial regimen with Moderna or Janssen was received. There are no data yet to assess the protection offered by the third doses against severe cases of MERS-CoV that require hospitalization. The UK Health Security Agency (UKHSA) will revise its analysis of the effectiveness of the third dose in the coming weeks as it has a larger sample of cases to study.
With current data, there is already “evidence of a decrease in protection against symptomatic disease after ten weeks of a booster dose, with a reduction in vaccine efficacy of 15% to 25% after ten weeks,” the Occupational Health and Safety Services Authority (UKHSA) concluded in Report that you have submitted your first results.
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