Centers for Disease Control and Prevention vaccine advisers voted unanimously Thursday to recommend that the Johnson & Johnson COVID-19 vaccine take a back seat to Moderna and Pfizer shots, when possible, due to risks of adverse side effects.

Serious clotting events, specifically thrombosis with thrombocytopenia, or TTS, are a rare but serious side effect of the Johnson & Johnson COVID-19 vaccines. The CDC Advisory Committee on Immunization Practices said the risks of the Johnson & Johnson vaccine do not necessarily outweigh its benefits, but when given an option, the benefit-risk balance leans toward mRNA vaccines across all age groups and sexes.

The 15-0 vote is just the latest in a series of setbacks for the Johnson & Johnson COVID-19 vaccine.

The vaccine was authorized for adults 18 and older on Feb. 27. In April, the Food and Drug Administration paused the use of the one-shot vaccine across all age groups after initial reports of blood clots following vaccination. Public health experts and the FDA and CDC later determined the vaccine was safe to bring back to market, as long as physicians knew what rare side effects to watch for. On Dec. 14, the FDA updated the Johnson & Johnson COVID-19 emergency authorization fact sheet to warn of the rare side effects.

If the CDC accepts the committee’s latest preferential recommendation, it could create an unequal distribution of adverse events related to the Johnson & Johnson vaccine, some advisers warned. The one-shot COVID-19 vaccine is often given to vulnerable populations, such as people experiencing homelessness and incarcerated individuals.

ACIP member Jamie Loehr compared the conundrum to the trolley problem in ethics, where one has a choice of allowing a runaway trolley to continue on a track and kill several people or divert it to another track where one person would die.

“If we take away the Janssen vaccines and people choose not to get the mRNA vaccine, we will have all these complications from COVID disease. And so, even though there are significant risks to the [Johnson & Johnson] vaccine, if it is the only one that is an option, I want it to be available,” Loehr said. Janssen is part of Johnson & Johnson.

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The clots in question, TTS, are most commonly seen in women ages 30 to 49, at a rate of one case per 100,000 doses. Roughly one in seven cases has been fatal.

As of Dec. 9, the CDC has recorded nine deaths after the first dose of the Johnson & Johnson covid-19 vaccine due to TTS blood clots. Seven of the individuals who died were female and two were male, averaging 45 years old. Most of these cases occurred before the FDA and CDC paused use of the Johnson & Johnson vaccine in the spring.

So far in the United States, about 17 million people have received an initial vaccine series from Johnson & Johnson, but most Johnson & Johnson recipients who got a booster received an mRNA shot, with 40 percent receiving one made by Moderna and 38 percent receiving a Pfizer-BioNTech booster.

Many countries already have different recommendations for adenovirus vaccines such as the Johnson & Johnson vaccine. Fourteen countries have special recommendations for the use of the AstraZeneca COVID-19 vaccine, which has properties similar to the Johnson & Johnson shot. Four countries, including Canada, give preferential treatment to mRNA vaccines.
Possible inequalities

Some ACIP advisers expressed concern that a recommendation against the Johnson & Johnson vaccine could have detrimental impacts on vulnerable populations.

In some populations and settings, Johnson & Johnson is the only vaccine offered. This often occurs in harder-to-reach populations, This could create an imbalance in who has adverse events after vaccinations. About 70 percent of vaccinated homeless and homebound individuals received the Johnson & Johnson vaccine in the U.S., as did 63 percent of incarcerated individuals and 57 percent of rural individuals.

ACIP member Oliver Brooks said members should keep in mind that the committee’s decision impacts how other countries distribute vaccines globally across multiple platforms.

Despite members’ push to keep the shot on the market, many expressed hesitancy to get the shot themselves.

“Would I recommend it to my family members? I would not recommend a Janssen vaccine to my family members. On the other hand, I think we do have to recognize that different people, different choices, and if they are appropriately informed, I don’t think we should remove that option from them,” ACIP member Beth Bell said.