CDC recommendations on COVID-19 vaccine boosters, new data on vaccine effectiveness

Several groups in the U.S. are now eligible to receive a booster dose of the Pfizer-BioNTech COVID-19 vaccine at least six months after completing the initial two-dose series.

The CDC last week recommended a booster dose of the Pfizer-BioNTech COVID-19 vaccine for several groups in the U.S.

On Sept. 22, the FDA announced that it had amended the emergency use authorization (EUA) for the Pfizer-BioNTech mRNA COVID-19 vaccine to allow for use of a single booster dose at least six months after the second dose in those ages 65 years and older, those ages 18 to 64 years who are at high risk for severe COVID-19, and those ages 18 through 64 years who are at high risk for serious COVID-19 complications because of frequent institutional or occupational exposure.

The CDC's Advisory Committee on Immunization Practices voted on Sept. 23 in favor of a booster dose six months after the primary series of the Pfizer-BioNTech shots in those ages 65 years and older and residents in long-term care settings, as well as those ages 50 to 64 years with underlying medical conditions. The committee also said that those ages 18 to 49 years with underlying medical conditions may receive a booster shot of Pfizer-BioNTech's COVID-19 vaccine at least six months after the initial series based on their individual benefits and risks.

The committee did not vote in favor of a booster shot for those ages 18 to 64 years who are at increased occupational or institutional risk for COVID-19 exposure and transmission. However, Rochelle Walensky, MD, FACP, the CDC director, included that category of people in the final CDC recommendations released on Sept. 24, meaning that groups such as teachers and health care workers are now eligible for a booster dose. The FDA's amended EUA and the CDC's recommendations apply only to the Pfizer-BioNTech vaccine, but the CDC said it will continue to urgently review data to make recommendations when possible for those who have received the Moderna or J&J/Janssen vaccine.

Multiple recent studies quantified the effectiveness of the COVID-19 vaccines. A case-control study of health care workers from 25 states, published by the New England Journal of Medicine (NEJM) on Sept. 22, calculated the effectiveness of the vaccines at preventing symptomatic COVID-19: 88.8% for Pfizer-BioNTech and 96.3% for Moderna. Vaccine effectiveness was similar by age (younger or older than 50 years), race and ethnic group, or presence of underlying condition. Vaccine effectiveness appeared lower nine to 14 weeks after receipt of the second dose compared to earlier, but the confidence intervals overlapped widely, the study authors noted. An analysis of participants in a trial of the Moderna vaccine, published the same day by NEJM, found that vaccine to be 93.2% effective at preventing illness at a median follow-up of 5.3 months. Efficacy was 98.2% against severe disease and 63.0% against asymptomatic infection and was again consistent across ethnic and racial groups, age groups, and participants with coexisting conditions. A British study, published by The BMJ on Sept. 17, identified factors associated with COVID-19 hospitalization and death despite vaccination, which included Down's syndrome, transplant, sickle cell disease, care home residency, chemotherapy, HIV, cirrhosis, and neurological conditions.

In treatment news, the World Health Organization updated its living guideline on drugs for COVID-19 to recommend combination monoclonal antibody treatment with casirivimab and imdevimab for patients with nonsevere COVID-19 who are at highest risk for hospitalization and those with severe or critical COVID-19 who are seronegative. The treatment is not likely to yield meaningful benefit in other COVID-19 patients, the guideline said. The guideline was updated Sept. 24 in The BMJ.

Finally, in an Ideas and Opinions piece published by Annals of Internal Medicine on Sept. 28, a group of ACP leaders, including Darilyn V. Moyer, MD, FACP, ACP's EVP/CEO, called on health systems, hospitals, and clinical practices to take tangible steps to preserve the clinician workforce during the COVID-19 pandemic. Among the recommended steps are the following:

  • ensuring physical safety by reducing clinicians' risk of contracting COVID through vaccination mandates, policies and practices that ensure universal masking and adequate ventilation in work areas, and access to personal protective equipment;
  • supporting clinicians who are parents by offering flexible work schedules and support groups and by supporting policies for reducing SARS-CoV-2 transmission in school settings;
  • adopting robust antidiscrimination and antiharassment policies to acknowledge and mitigate harm, particularly against minoritized people;
  • offering free and confidential resources to support clinicians' mental health, including the ACP I.M. Emotional Support Hub;
  • updating credentialing and employment applications to remove unnecessary questions about mental and physical health diagnoses;
  • and implementing suicide prevention strategies, including “wellness check-ins” for clinicians in hard-hit areas.

Organizations should work with their frontline clinicians to determine which measures would have the most impact and be the most feasible to implement in their current environments, the paper said. “The entire health care system can benefit when clinicians receive material, logistic, and tactical support, and foundational themes have long been recommended,” the authors wrote. “The adage that no crisis should go to waste presents us with many opportunities to do better—and the ongoing waves of the pandemic create a new urgency to do so.”