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Why the Johnson & Johnson vaccine pause was the right move

The CDC and FDA on Friday accepted recommendations that Johnson & Johnson Covid-19 vaccinations should resume, but with a warning.

Bottles of Johnson & Johnson’s Covid-19 vaccine.
Advisers to the CDC recommended that distribution of the Johnson & Johnson Covid-19 vaccine resume after reports of rare blood clots.
Jorge Guerrero/AFP via Getty Images
Umair Irfan is a correspondent at Vox writing about climate change, Covid-19, and energy policy. Irfan is also a regular contributor to the radio program Science Friday. Prior to Vox, he was a reporter for ClimateWire at E&E News.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) on Friday evening accepted recommendations from an advisory group to lift the pause on the one-dose Covid-19 vaccine from Johnson & Johnson after determining that the benefits of the vaccine far outweigh its risks. The vaccine, however, should now come with a warning about the risk of blood clots, they said.

The agencies instituted a pause on the Johnson & Johnson vaccine on April 13 after six cases of a rare type of blood clot leading to one fatality were reported in people who had received the shot. The injection has already been administered to 8 million people in the US.

By the time the advisory group to the CDC met on Friday, there had been 15 cases of blood clotting complications known to be associated with the vaccine, including three deaths. Seven of these patients remain hospitalized while five have been discharged.

“These cases are not just numbers to any of us, and we take them very seriously,” said Joanne Waldstreicher, the chief medical officer of Johnson & Johnson, during the meeting of advisers on Friday. “These are people.”

While these complications are serious, it’s also clear that they are extremely rare. This posed a challenge for regulators in how to handle the risks as well as how to communicate the concerns to the public without undermining vaccination efforts. So far, though, it seems Americans remain confident in Covid-19 vaccines.

Having a third vaccine back online in the US could help close gaps in vaccination, particularly since the Johnson & Johnson vaccine only requires one dose instead of the two needed for the Moderna and Pfizer/BioNTech Covid-19 vaccines. Johnson & Johnson’s vaccine is also cheaper and can be stored in ordinary refrigerators rather than freezers.

It’s also an important player in the global race to contain Covid-19. In addition to its lower costs and logistics requirements, the Johnson & Johnson vaccine has been shown to be effective against the new, more dangerous variants of the virus that causes Covid-19. South Africa, which is fighting a fast-spreading variant, decided to resume distribution of the Johnson & Johnson vaccine this week after the country paused its own distribution campaign last week.

On balance, experts say the decision to pause distribution of the Johnson & Johnson vaccine to investigate these complications was the right one, but some argue that the decision to resume could have been made sooner, particularly given the continued onslaught of the Covid-19 pandemic.

What we know about the Johnson & Johnson vaccine and blood clots

The complication of concern here is known as thrombosis with thrombocytopenia syndrome (TTS), or vaccine-induced immune thrombotic thrombocytopenia (VITT).

Thrombocytopenia is a condition where platelets, blood cells that help form blood clots, drop to abnormally low levels in the bloodstream. That can lead to bruising and uncontrolled bleeding.

In the case of the Johnson & Johnson and the Oxford/AstraZeneca Covid-19 vaccines, it seems that the vaccines in very rare cases can trigger an autoimmune response. White blood cells form proteins called antibodies that normally target hostile invaders, but in these cases, antibodies are binding to proteins that trigger platelets to form clots.

Those clots can spread throughout the body and have, alarmingly, been found in blood vessels leading away from the brain, a condition known as cerebral venous sinus thrombosis, or CVST. This can quickly turn deadly.

So the problem ends up being that so many platelets are consumed in making these unnecessary and dangerous blood clots that not enough are left over to form clots where they are actually needed.

That means that traditional treatments for clots like heparin, a blood thinner, won’t work here and could actually make the situation worse.

The blood clotting complications also mirror similar problems associated with the AstraZeneca/Oxford Covid-19 vaccine. Both of these vaccines use a modified version of another virus to deliver DNA instructions for making the spike protein of SARS-CoV-2, the virus that causes Covid-19. It hints that there is a common mechanism at work.

But again, this is such a rare complication that only 15 cases were reported out of 8 million Johnson & Johnson shots. All of the cases were reported in women, with 13 TTS cases in those between the ages of 18 and 49 and two above the age of 50. Beyond warning young women to keep an eye out for any blood clot-related symptoms — headache, blurred vision, seizures, pain in the extremities, and a loss of control of the body — there’s not much health officials can offer in terms of screening vulnerable people.

Chart showing rates of TTS after receiving Johnson & Johnson’s Covid-19 vaccine
Only a handful of cases of TTS were observed in people who received the Johnson & Johnson/Janssen Covid-19 vaccine.

“The benefits of the vaccine far outweigh the risk, at least in the older population,” said Robert Brodsky, director of the hematology division at Johns Hopkins University.

And if patients are concerned about blood clots, Brodsky said the risk of clots from contracting Covid-19 is far, far greater than the likelihood of one occurring in the wake of a vaccine. “My concern is that this vaccine gets deep-sixed,” he said. “It’s a very effective vaccine.”

The recommendation to lift the pause of the Johnson & Johnson vaccine echoes a similar decision from the European Medicines Agency (EMA) — the European Union’s pharmaceuticals regulator — on Wednesday. The EMA also said that a warning about rare blood clots should be added to the list of side effects for the vaccine. (The Johnson & Johnson vaccine is often identified with the name of its subsidiary Janssen in Europe.)

The pause turned out to be the right decision for the US

One of the main fears with the pause on the Johnson & Johnson Covid-19 vaccine was that it would undermine public trust in vaccines, but polls seem to show that’s not the case.

An April 14 poll of 600 adults found that 58 percent of respondents were more confident in Covid-19 vaccines after the pause.

Another poll on April 15 of 1,000 adults found that 36 percent of respondents saw no change in their likelihood of getting a vaccine and 40 percent said they were more likely to get a Covid-19 shot after the pause was announced. And a poll of 1,033 adults between April 16 and 19 found that 88 percent of respondents thought that the FDA and CDC were being responsible in pausing the Johnson & Johnson shot.

So it seems that most Americans were not fazed by the pause to review the vaccine, which was a relief for some observers.

“When I woke up that day, I was really depressed that they had paused the J&J vaccine rollout ... I thought that it would increase vaccine hesitancy,” said Monica Gandhi, an infectious disease doctor and a professor of medicine at the University of California San Francisco. “However, I actually changed my mind over the ensuing week.”

She noted that the polls aligned with the attitudes she saw in patients, who appreciated that regulators were taking safety issues seriously. Another factor that changed her mind is that with so many vaccines already administered in the US, the challenge now is convincing the remaining people who are more reluctant to get immunized.

“Anything that we can do to assure people who are still concerned about the safety of these vaccines, that everything is going to be closely looked at, I think will hopefully increase vaccine uptake,” Gandhi said.

But the pause had an opportunity cost. People who were in line to get the Johnson & Johnson vaccine had to scramble to find alternatives. And now more than a week has passed where people who otherwise would have had some degree of protection against Covid-19 may not have any.

Though pausing the distribution of the vaccine was warranted, waiting more than a week to make a decision about it was likely excessive, according to Eric Topol, director of the Scripps Research Translational Institute. “There was enough data to make the call last Wednesday,” he said.

Topol added that while vaccine confidence remains high in the US, it’s also important to keep the international context in mind with respect to Covid-19. People in the US also have multiple effective vaccines in circulation while other countries barely have any, and hesitancy on other continents is already on the rise. How the US manages rare complications will ripple into other countries. “The US is in the fishbowl of the world,” he said.

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