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Booster Dose of COVID-19 Vaccine for the Immunocompromised Coming Soon

The Food and Drug Administration (FDA) is expected to expand the Emergency Use Authorization (EUA) of the Pfizer-BioNTech and Moderna vaccines for a third dose in those who might be vulnerable to COVID-19.

People with immunocompromised systems might become eligible for a booster dose of the m-RNA vaccines as early as today. The expected FDA announcement of the expansion of the existing EUA of the Pfizer-BioNTech and Moderna vaccines might be coming later on Thursday because of the emergence of the delta variant, the concerns of waning or no immunity in some immunocompromised patient populations, and the appearance of a small percentage of breakthrough infections.

All those aforementioned factors have prompted public health officials to reexamine their initial reluctance to consider a booster dose. Just a few weeks ago, reports stated that the US Centers for Disease Control and Prevention (CDC) and National Institutes of Health (NIH) were hesitant to expand the EUA. 

Back in July, a joint statement from the FDA and CDC reiterated the sustained efficacy of two-dose mRNA vaccines against preventing COVID-19 severe disease. They noted that efficacy included “variants currently circulating in the country such as delta.”

“Virtually all COVID-19 hospitalizations and deaths are among those who are unvaccinated,” they wrote. “Americans who have been fully vaccinated do not need a booster shot at this time.”

A report in the NY Times noted one particular patient group.“Studies suggest that patients such as organ transplant recipients are in between — often showing little immune response to the standard vaccine regimen, but benefiting from a third shot.”

In a study coming from England, and published in the New England Journal of Medicine, they reported on the differences in efficaciousness in the delta and alpha variants using the Pfizer-BioNTech vaccine. “With the BNT162b2 vaccine, the effectiveness of two doses was 93.7% (95% CI, 91.6 to 95.3) among persons with the alpha variant and 88.0% (95% CI, 85.3 to 90.1) among those with the delta variant.”

Moderna reported in its final analysis of its phase 3 COVE study, the data demonstrated a 93% efficacy, with the efficacy remaining durable through 6 months after administration of the second dose. The company is actively developing booster shots. In a phase 2 study, vaccination with 50 µg of 3 different booster candidates induced robust antibody responses against the wild type D614G COVID-19 strain and against the gamma, beta, and delta variants.

“Only modest differences in vaccine effectiveness were noted with the delta variant as compared with the alpha variant after the receipt of two vaccine doses,” the investigators concluded in their study.

Israel has reported a waning immunity in their data. In a report in the Wall Street Journal, the findings showed reduced efficacy in the Pfizer vaccine.

With this new data, other countries such as Israel, Germany, and France looking at booster doses, and waning immunity concerns, the immunocompromised might be the first patient population that will be eligible for the third shot and then others such as seniors and eventually everyone else by later this year.

Although the FDA EUA decision could come today, a CDC panel is scheduled to meet tomorrow and it could influence health care providers and health systems to act depending on what the guidance is from the latter federal agency.