To date, over 104 million people in the United States have been fully vaccinated with Pfizer’s product, over 69 million with Moderna, and approximately 15 million with the Johnson & Johnson vaccine.
The government decided last month to offer booster shots of the Pfizer vaccine to older Americans and other high-risk groups, and the panel voted Thursday to recommend the same approach for Moderna beneficiaries. More than eight million people in the United States have already received booster doses of Pfizer, and approximately 1.6 million have received third doses of Moderna, although only recipients of Moderna with immune deficiencies are officially eligible.
For Johnson & Johnson beneficiaries, the committee recommended an additional injection for anyone who had received the vaccine – a reflection of its lower effectiveness. Although the added injection was intended as a booster, some experts on the committee argued that the vaccine should have involved two doses from the start, separated by about two months.
Johnson & Johnson officials said that a second dose given two or six months after the first injection increased antibody levels, part of the immune response to vaccines. They also said that, unlike Pfizer’s vaccine, Johnson & Johnson’s potency did not decrease significantly over time.
Experts generally agreed that the protection conferred by a single dose was insufficient, but at least some were not convinced that the second dose would significantly enhance this protection.
What to know about Covid-19 booster injections
They criticized the company’s data, saying FDA regulators challenged the sensitivity of a key test used to measure antibodies in people given booster doses. They balked at the size of a study of Johnson & Johnson booster doses given six months apart, based on just 17 volunteers. And they were clearly distressed to see slide after slide of data with the huge caveat: “Not verified by the FDA.”
Dr. Archana Chatterjee, Dean of Chicago Medical School, made it clear why the FDA was pushing for a decision without a full review.