Research, regulators consider booster dose of COVID-19 vaccine

Booster vaccine doses were the focus of COVID-19 news and research last week. On Sept. 17, the FDA's Vaccines and Related Biological Products Advisory Committee unanimously recommended a third booster shot of the Pfizer-BioNTech vaccine for patients 65 years and older or at risk of serious disease from SARS-CoV-2. The committee voted against booster shots for the general population, but in an unofficial poll, unanimously supported a booster dose for health care workers or others at high risk of occupational exposure, according to NPR. Its advice is not binding but will be considered by the FDA.

A retrospective study in Israel, published by the New England Journal of Medicine (NEJM) on Sept. 15, reported the effects of a booster dose of the Pfizer-BioNTech vaccine in patients age 60 years or older. The month-long study compared more than 10 million patient-days after receipt of a booster to more than 5 million days in patients who had gotten only two doses, finding 934 confirmed infections, 29 of them severe, in those who received a booster versus 4,439 confirmed infections, 294 of them severe, in those who had not. The authors calculated that the booster decreased the rate of COVID-19 infection by a factor of 11.3 (95% CI, 10.4 to 12.3) and the rate of severe illness by a factor of 19.5 (95% CI, 12.9 to 29.5). “Our findings give clear indications of the effectiveness of a booster dose even against the currently dominant delta variant,” the authors said.

Similarly, a letter published by NEJM the same day reported SARS-CoV-2 neutralization geometric mean titers in 23 people who received a third dose of Pfizer-BioNTech vaccine as part of a U.S. trial. “The safety and immunogenicity of a booster dose of BNT162b2 administered 7 to 9 months after the primary two-dose series suggest that a third dose could prolong protection and further increase the breadth of protection,” the authors observed.

However, a group of experts expressed concerns about providing boosters to anyone other than immunocompromised patients in a Viewpoint published by The Lancet on Sept. 13. They reviewed the latest literature on the effectiveness of two doses and a third booster shot and said, “Current evidence does not, therefore, appear to show a need for boosting in the general population, in which efficacy against severe disease remains high.” The relative effectiveness of the three authorized vaccines was compared in a study published by MMWR on Sept. 17. It looked at 3,689 adults from 18 states without immunocompromising conditions who were hospitalized during the period from March 11 to Aug. 15 and calculated that vaccine effectiveness against COVID-19 hospitalization was 93% for the Moderna vaccine, 88% for the Pfizer-BioNTech vaccine, and 71% for the J&J/Janssen vaccine.

In other COVID-19 research, a randomized, open-label trial in Europe did not find benefit from remdesivir for hospitalized patients with COVID-19. Clinical status at day 15 was similar in the 429 patients who received remdesivir plus standard of care and the 428 who got standard care, according to results published by The Lancet Infectious Diseases on Sept. 14. A letter published by NEJM on Sept. 15 reported that severe headache may precede vaccine-induced immune thrombotic thrombocytopenia.

A Michigan study found that most patients hospitalized with COVID-19 didn't have outpatient follow-up scheduled before discharge and scheduling varied widely by hospital, according to results published by the Journal of General Internal Medicine on Sept. 14. Finally, the NIH's treatment guidance panel updated its recommendations on monoclonal antibodies in response to the predominance of the delta variant.