Millions of Americans who got the Moderna and Johnson & Johnson coronavirus vaccines have had to watch those who received the Pfizer vaccine roll up their sleeves for a booster shot, wondering when they will get the same chance at extra protection.

This Thursday and Friday, an advisory panel to the U.S. Food and Drug Administration will tackle that pressing question.

The panel’s deliberations will be the first step taken in deciding whether extra doses of the two vaccines should be given. Once the FDA advisers make their recommendation, the agency itself will make a decision on whether to authorize boosters for those shots. If the FDA approves the extra doses, a panel convened next week by the U.S. Centers for Disease Control and Prevention will recommend more specifics on who should get them.

As a final measure, the CDC panel’s decision has to be approved by Dr. Rochelle Walensky, director of the U.S. Centers for Disease Control and Prevention.

As simple and straightforward as that process may sound, documents released by the FDA on Tuesday indicate that these decisions may not be easy ones.

What are the trickiest questions? When the FDA’s panel meets this week to review whether to recommend booster shots of the Moderna and J&J vaccines, experts will discuss whether a third Moderna shot should contain just half the original dose, as well as the best timing for a second shot of the single-dose J&J vaccine, the Associated Press reported. The panel will also look into the safety and effectiveness of mixing and matching different brands of vaccine, something regulators have not endorsed so far.

Beyond the question of waning efficacy of COVID-19 vaccines, some experts say there is a need to “harmonize” the country’s booster strategy.

“We’re in this very complicated situation right now: People are going into pharmacies or places where vaccines are available and saying, ‘I want my third dose of Moderna, or I want my second dose of J.&J.,” Dr. H. Cody Meissner, an infectious disease expert at Tufts Medical Center who serves on the FDA advisory panel, told The New York Times. “I don’t think anyone has much doubt that we will need a booster dose for these vaccines. What we don’t know is: How urgent is the need?”

An estimated 103 million Americans are now fully vaccinated with Pfizer’s formula, 69 million with Moderna’s and 15 million with J&J’s, according to the CDC. Regulators took up the question of Pfizer boosters first because the company submitted its data ahead of the other vaccine makers.

In the new review of Moderna’s latest data, the FDA did not indicate if it was leaning toward approving the company’s booster shot. The agency did say that vaccines used in the United States still provide protection, and it raised questions about some of Moderna’s efficacy data, the AP reported.

The two initial Moderna shots contain 100 micrograms of vaccine each. But the drugmaker said in documents filed with the FDA that 50 micrograms ought to be enough for a booster for healthy people.

A company study of 344 people gave them a 50-microgram shot six months after their second dose, and levels of virus-fighting antibodies jumped. Moderna said the booster even triggered a 42-fold rise in antibodies able to target the highly contagious Delta variant.

Side effects were similar to the fevers and aches that Moderna recipients commonly experience after their second regular shot, the company said.

As for people who got the J&J vaccine, the company has submitted data to the FDA for two different options: a booster shot at two months or at six months. The company said in its FDA submission that a six-month booster is recommended but that a second dose could be given at two months in some situations, the AP reported.

J&J released data in September showing that a booster given at two months provided 94% protection against moderate-to-severe COVID-19 infection. The company has not disclosed patient data on a six-month booster, but early measures of virus-fighting antibodies suggest it provides even higher protection.

Even without a booster, J&J says, its vaccine remains about 80% effective at preventing COVID-19 hospitalizations.

Scientists emphasize that all three vaccines still offer strong protection against severe disease and death from COVID-19. The thorny issue is how quickly, and how much, protection against milder infection may wane.

More information

Visit the U.S. Food and Drug Administration for more on COVID vaccines.

Source: HealthDay