Some short-term benefit of additional booster dose of mRNA vaccine in health workers: WHO

A 4-6 month interval since the completion of the vaccine primary series may be considered for a first booster, WHO says

A 4-6 month interval since the completion of the vaccine primary series may be considered for a first booster, WHO says

The World Health Organization (WHO) has said there is a benefit to administering an additional booster dose of the mRNA COVID-19 vaccine to the highest-risk groups, health professionals, people over the age of 60 or with immunocompromising conditions.

As a general principle, an interval of 4-6 months after completion of the primary series of vaccines can be considered for a first booster, especially in the context of Omicron, the WHO said, with the support of the Strategic Advisory Group of Experts (SAGE) on immunization and the working group on COVID-19 vaccines.

The WHO said that when considering supplemental booster doses, the two main scenarios to consider are the use of supplemental booster doses in those who are unable to mount and sustain an adequate immune response and considerations for administration of additional booster doses to protect high blood pressure. populations at risk and health professionals to maintain the health system during periodic waves of disease waves.

It said available data for WHO EUL COVID-19 vaccine products suggest that vaccine effectiveness and immunogenicity are lower in immunocompromised individuals (ICPs), compared to individuals without immunocompromising conditions.

“An additional dose in an extended primary series improves immune responses in some ICPs. Given the significant risk of severe COVID-19 for ICPs, if infected, the WHO has already recommended an extended primary series (i.e. third dose) and a booster dose (ie fourth dose) for ICPs, for all COVID-19 vaccines,” it sounds.

The WHO noted that additional booster doses are currently being offered by some countries in addition to the initial booster dose, adding that data on additional booster doses as of May 2022 only exist for the mRNA vaccines and not for other vaccine platforms.

The WHO cited seven studies, conducted at a time when Omicron was the predominant circulating strain worldwide, that evaluated the relative effectiveness of a fourth dose four months after a third dose of mRNA vaccine compared to those who received three doses.

Taken together, these studies show some short-term benefit of an additional booster dose of mRNA vaccine in health professionals, people over the age of 60, or with immunocompromising conditions,” the WHO said.

It said the data to support an additional dose for healthy younger populations is limited; preliminary data suggests that the benefit is minimal in younger people.

“The limited data available suggests that for groups at the highest risk there is a benefit supporting the administration of an additional booster dose,” the WHO said, adding that in those most at risk of serious illness or death (i.e. adults older than 60 years of age, or those unable to mount a full immune response), the added benefit of an additional booster dose of mRNA vaccine may be “legitimate.”

It said that while seasonality has not yet been fully established for SARS-COV-2, evidence from the past two years supports the idea of ​​more substantial transmission during the winter season.

“Therefore, campaigns for countries with a winter season in the Northern or Southern hemisphere, catch-up plans to improve coverage of the primary series and boost those at highest risk, should take seasonality into account,” the WHO added. to.

SOURCE – www.thehindu.com

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