The panel said at that meeting it needed more data on the risks, cause and frequency of the rare brain blood clots before recommending a lift to the pause or other steps, such as restrictions based on age or gender.
Federal health authorities are leaning toward recommending that use of the vaccine resume, possibly as soon as this weekend — a move that would include a new warning about a rare complication involving blood clots but probably not call for age restrictions. The stance of U.S. authorities was described by two government officials who spoke on the condition of anonymity to discuss internal deliberations.
Any advisory panel recommendation would need to be approved by CDC director Rochelle Walensky.
If the United States lifts the pause and adds a warning to the vaccine’s label, the position would be similar to one taken by Europe’s drug regulator, the European Medicines Agency, which said this week the Johnson & Johnson vaccine should carry a warning but placed no restrictions on its use. The European agency said the shot’s benefits continue to outweigh the risks.
Since the U.S. pause was announced, Walensky has said a “handful” of additional cases have been reported, but in interviews this week, she and Janet Woodcock, the acting FDA commissioner, declined to elaborate. They have said they are encouraged by the relatively small number of additional cases.
The rarity of cases has persuaded many federal officials that the complication can be addressed by adding a warning that describes the groups at higher risk for the adverse event, and by working to ensure that doctors know how to identify and treat the problem. People who have received the Johnson & Johnson vaccine and develop severe headaches, abdominal pain, leg pain or shortness of breath within three weeks after vaccination should contact their medical provider. Most notably, physicians are advised to avoid using heparin, a common treatment for blood clots, because it can exacerbate the vaccine-related condition.
Experts have said the risk of developing a clot after receiving the vaccine appears far lower than the chance of a clotting issue caused by a severe covid-19 infection or from using hormonal birth control, such as oral contraceptives.
Some public health experts who said they were dismayed by last week’s decision to leave the pause in place said they hope the committee puts the risks of the Johnson & Johnson vaccine in the proper context.
“Any time you pause something, you should know the conditions under which you will lift the pause,” said Nirav Shah, Maine’s top health official and president of the Association of State and Territorial Health Officials. “There should be an agreed-upon theory of safety.”
If the CDC advisory committee votes Friday to lift the pause, the CDC and FDA could recommend resuming the shots within hours or days. That would be good news for state officials eager to begin using the one-dose vaccine again. But if the advisory panel has a different view — and recommends, for example, that the vaccine not be used for certain age groups or not be used at all for now — it is not clear what happens next.
The six cases of blood clots previously identified by officials occurred in women between the ages of 18 and 48. They developed symptoms, most often headaches, six to 13 days after vaccination. One vaccine recipient, a Virginia woman, died in March. In all cases, the clots were seen in combination with low levels of blood-clotting cells, known as platelets, a condition known as thrombocytopenia.
All of the women were White, and only one was taking hormonal contraceptives that can cause blood clots, suggesting that was not the reason for the clots.
Some of the women had blood clots in other parts of their body, and CDC officials said last week the agency would cast a wider net, looking for clotting accompanied by low levels of platelets. Four of the vaccine recipients of the Johnson & Johnson vaccine were treated initially with heparin, an anticoagulant that is not recommended because the events closely resemble an immune-triggered reaction to the drug that could worsen the clots.
Johnson & Johnson presented data on two other cases of clots in people who received the vaccine during a clinical trial, one of whom was a 25-year-old man with a hallmark of the symptoms.
Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said officials want to “find the sweet spot where people have the information they need to make an informed choice on benefits and risks. … The way the FDA is seeing it, the overall benefit and risk here remains favorable.”
He said it wouldn’t be surprised to have a doubling of confirmed cases from the six originally identified by U.S. officials, considering the number of people who have received the vaccination.
The Johnson & Johnson vaccine, which was authorized for adults 18 and over, was a large part of the U.S. and global vaccination strategy. It has clear practical and logistical advantages over the other two authorized vaccines in the United States — it does not have to be kept frozen, and requires just one dose. That makes it particularly useful for rural areas and other hard-to-reach communities, and for distribution to community health centers and physician offices that might not have the freezers needed for the other vaccines, public health officials say.
South Africa announced Thursday it will resume using the Johnson & Johnson vaccine to immunize health-care workers against the coronavirus after the country suspended the vaccination program when U.S. officials reported the rare blood clots. There have been no incidents of blood clots reported in South Africa.
About 290,000 of South Africa’s 1.2 million health workers have been given the Johnson & Johnson vaccine in a study that is evaluating the vaccine before a mass rollout to combat an aggressive variant detected in the country last fall.
Laurie McGinley contributed to this report.