Covid-19: Americans who are over 50 or immunocompromised are advised to have second booster
BMJ 2022; 376 doi: https://doi.org/10.1136/bmj.o842 (Published 30 March 2022) Cite this as: BMJ 2022;376:o842
Second booster doses against covid-19 for Americans aged over 50 and for certain immunocompromised people aged over 12, using either the Pfizer-BioNTech or the Moderna vaccine, may become available as early as later this week after they were authorised in the US.
The new recommendations from the Food and Drug Administration (FDA)1 and the Centers for Disease Control and Prevention (CDC)2 come as the BA.2 omicron variant spreads rapidly in the US and is responsible for about 55% of new infections. The variant seems to be more contagious but does not cause more severe infections.3
Peter Marks, director of the CDC’s Center for Biologics Evaluation and Research, said on 29 March, “Current evidence suggests some waning of protection over time against serious outcomes from covid-19 in older and immunocompromised individuals. Based on an analysis of emerging data, a second booster dose of either the Pfizer-BioNTech or Moderna covid-19 vaccine could help increase protection levels for these high risk individuals.
“Additionally, the data show that an individual booster dose is critical in helping to protect all adults from the potentially severe outcomes of covid-19. So, those who have not received their initial booster dose are strongly encouraged to do so.”
Marks said that another covid-19 booster might be needed in the autumn. The FDA will hold an advisory committee meeting on 6 April to consider boosters and possible updates to the existing vaccines.4
The FDA recommended the second booster to be given to over 50s at least four months after the first booster. Thus it will be the fourth vaccine dose for people who have already received the two dose Pfizer-BioNTech and Moderna vaccines plus a booster.
The agency previously recommended a single booster dose for some immunocompromised people after they had received a three dose primary immunisation. Such immunocompromised people aged over 12 should then receive another booster—the fifth shot—at least four months after the previous booster dose.
For people who received two doses of the Johnson & Johnson vaccine the FDA recommends an mRNA vaccine booster.
Ongoing study
Rochelle Walensky, CDC director, called the recommendations “especially important” for older people with underlying medical conditions that increase their risk for severe disease if they get covid-19, as “they are most likely to benefit from receiving an additional booster dose at this time.”
The FDA said that it was authorising the second booster dose for “populations at higher risk for severe disease, hospitalisation, and death. Emerging evidence suggests that a second booster dose of an mRNA covid-19 vaccine improves protection against severe covid-19 and is not associated with new safety concerns.” The CDC previously noted that vaccine efficacy waned over time.5
The FDA’s decision in favour of a second booster relied on an ongoing, open label, non-randomised clinical study in healthcare workers at a single centre in Israel. Health workers aged over 18 received the two dose Pfizer-BioNTech vaccine and a booster, followed at least four months later by a second booster of either the Pfizer-BioNTech vaccine or the Moderna vaccine.
The FDA said, “Among these individuals, increases in neutralising antibody levels against the SARS-CoV-2 virus, including delta and omicron variants, were reported two weeks after the second booster as compared to five months after the first booster dose.”
A preprint of another Israeli study showed that mortality from covid-19 was 78% lower after a second booster in a group of people over 60.6
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