US health officials have lifted an 11-day pause on Johnson & Johnson vaccinations following a recommendation by an expert panel. Advisers to the Centers for Disease Control and Prevention said Friday the benefits of the single-dose Covid-19 shot outweigh a rare risk of blood clots.

Panel members said it is critical that younger women be told about that risk so they can decide if they’d rather choose another vaccine. The CDC and Food and Drug Administration agreed. European regulators earlier this week made a similar decision, deciding the clot risk was small enough to allow the rollout of Johnson & Johnson’s shot.

The change comes after distribution of the Johnson & Johnson vaccine was temporarily halted while scientists investigated rare but dangerous blood clots with low platelet counts linked to the shot.

“This pause was essential to our ability to inform the public, inform physicians and the acquire more data for presentation and for analysis,” said Dr Jose Romero, the chair of the CDC’s committee on immunization practices, which advises on how to best use vaccines. The committee vote was 10 to four in favor of recommending the vaccine for adults older than 18. There was one abstention.

Janet Woodcock, the acting FDA commissioner, said the pause was an example of safety monitoring precautions working as intended. “We’ve lifted the pause based on the FDA and CDC’s review of all available data,” she said. “We are confident that this vaccine continues to meet our standards for safety, effectiveness and quality.”

More than 570,000 Americans have died of Covid-19, according to Johns Hopkins University, and 31 million people have been infected with Covid-19 in the US, according to the CDC.

Health authorities at the CDC and the Food and Drug Administration (FDA) put Johnson & Johnson’s vaccine distribution on “pause” on 13 April while six cases of very rare blood clots in women aged 18-49 were investigated.

Since the pause, scientists have found nine more cases of the clots. That means among the more than 7.98m doses of Johnson & Johnson distributed, vaccine safety monitoring systems found 15 total cases. Doctors on the panel said the fact researchers were able to identify the very rare associated disorder shows the strength of US vaccine safety monitoring.

All confirmed cases were among women, most were middle-aged. Two were cases in women older than 50. The Johnson & Johnson clinical trial also found one case in a male and cases among men are under investigation.

Put another way, if 1 million people were vaccinated using the Johnson & Johnson vaccine, 2,000 fewer people would be expected to die of Covid-19, 6,000 fewer hospitalized, and seven people would be expected to develop the serious blood clots associated with the vaccine.

However, the individual risk for women younger than 50 is higher. Among 1 million people, 12 Covid-19 deaths and 657 hospitalizations would be expected to be prevented, with 13 cases of the blood clotting disorder expected, according to the CDC.

A description of the risks and symptoms of blood clots would appear in a patient fact sheet distributed with the vaccine. In the general population, between 0.7 and 1.6 people per million develop the specific type of blood clot with low platelet count associated with the vaccine.

It is not uncommon for the committee to modify recommendations as data is gathered across millions of people. The new recommendations from independent advisers will be taken into consideration by health authorities at the CDC and FDA, who are expected to act quickly on the advice. Though health authorities do not always take the advice of their independent advisory experts, they most often do.

Those that opposed the measure said the recommendation did not issue a strong enough warning. Dr Beth Bell, a public health professor at the University of Washington who voted against the measure, did not oppose resuming distribution of the Johnson & Johnson vaccine, she said.

“I am concerned the women will not be adequately informed just by [emergency use authorization] factsheets,” said Bell.

The Johnson & Johnson vaccine was temporarily halted while scientists investigated rare but dangerous blood clots.
The Johnson & Johnson vaccine was temporarily halted while scientists investigated rare but dangerous blood clots. Photograph: Dado Ruvić/Reuters

At the time of the pause, authorities said they hoped the high-profile announcement would help uncover any additional cases of the clotting disorder previously missed, and that the stoppage would give clinicians time to understand how to treat the disorder. Unlike most blood clots, those linked to the Johnson & Johnson vaccine cannot be treated with heparin, a common blood thinner.

Blood clots associated with the Johnson & Johnson vaccine are formally called thrombosis with thrombocytopenia, or blood clotting with low platelet count. Platelets are a component of blood that aids in clotting. The syndrome has been found to occur after more common flu-like side-effects resolve, between six and 13 days after vaccine administration.

A similar syndrome has been linked to a vaccine by AstraZeneca, which uses the same vaccine technology, called viral vector. In both instances, vaccine manufacturers used a second, weakened virus to deliver the genetic payload of the Sars-CoV-2 virus, prompting immunity.

Although the two manufacturers used different kinds of viral vectors, a chimpanzee virus in the case of AstraZeneca and a human virus in the case of Johnson & Johnson, authorities have said in the past conditions linked to the two vaccines bear a resemblance.

Not all experts agreed a “pause” was the best way to investigate the potential side-effect. Many argued it was unnecessary for such a rare side-effect, and that it could cause heightened vaccine hesitancy.

Confidence in the Johnson & Johnson vaccine has dropped significantly, the CDC said. In the two days following the announcement, there was a 15% decrease in confidence in the Johnson & Johnson vaccine.

Hesitancy is already playing a major role in the largest adult immunization campaign in US history, as states now have more open slots than takers, especially in areas with large populations of racial minorities and conservative voters.

Local health departments had also planned to use the vaccine to reach those most difficult to vaccinate, especially people who are homeless, incarcerated, homebound, or who are seasonal workers.

The advisory committee’s recommendation will not resolve all of Johnson & Johnson’s woes. More than 7.9 million Americans have received a Johnson & Johnson shot, and another 10 million wait in the wings. But the company has had serious manufacturing issues at a US facility expected to produce the bulk of the 100m doses the federal government expected the company to deliver by the coming summer.

The Associated Press contributed reporting

This content first appear on the guardian

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