The U.S. has temporarily paused the roll-out of the Johnson and Johnson COVID-19 vaccine. The vaccine was the last to be approved in the U.S., and only requires one-shot. 

According to the FDA, six cases out of 6.8 million doses of the vaccine found rare blood clots present. 

The rare clots were found in vessels leading out of the brain. All cases were in white women between the ages of 18 and 48. These side effects occurred six to 13 days following vaccination. 

While originally the changes were framed as a recommendation to health practitioners, every U.S. state, D.C., and Puerto Rico have announced a pause in distribution of the J & J vaccine.   

An advisory panel to the CDC will continue to investigate the vaccine to see if the rare blood clots continue. 

Many of the panelists said they do not have enough information right now to make a decision on whether or not to continue distributing the vaccine. Especially while the other two vaccines, Moderna and Pfizer, are widely available and have no safety concerns. 

“We do need to better understand the risk, which we know is going to be very rare, very low, but we really don’t know exactly how low,” said Dr. Beth Bell, a member of the advisory panel. 

Most of the experts agreed that the pause on the Johnson and Johnson vaccine will be temporary and hope to reconvene in the coming weeks to continue distribution. 

Some independent advisors from the Advisory Committee on Immunization Practices expressed concern over continuing the pause. 

“I continue to feel we’re in a race against time and the variants,” said Dr. Grace Lee, a member of ACIP. “But we need to do so in the safest possible way.”

While many doctors have argued that this delay should be seen as a positive for vaccine safety, other officials are worried about whether or not these reports will affect public confidence in vaccination. 

According to the News York Times, scores of vaccination appointments have been cancelled following the J&J report. 

Some public health officials worry that this information will fuel vaccine hesitancy and lead to fewer Americans getting vaccinated. 

“We are concerned about heightened reservations about the J&J vaccine, but in addition to that, those reservations could spill over into public concerns about other vaccines,” said the Chief Science Officer for the Los Angeles County Department of Public Health, Dr. Paul Simon. 

Conversely, the FDA and the CDC see the pause as an unavoidable step. 

“It’s incredibly challenging, but to ignore it would have been worse,” said Rachael Piltch-Loeb, an expert in health risk communication at the N.Y.U. School of Global Public Health. 

“If the public suspected that the government was concealing serious potential side effects, far more people might decide against vaccination.”

Abroad, regulators have run into similar issues of blood clotting with another COVID-19 vaccine, AstraZeneca. J&J and AstraZeneca are based on the same technology. 

Both Moderna and Pfizer use a different technology than J&J. More than 180 million doses of both vaccines have been administered and, according to the CDC’s latest statistics, they have found no evidence of blood clots. 

The lack of a third vaccine option, hurts the Biden Administration’s plan for vaccine distribution. 

With Moderna and Pfizer, federal officials expect to have enough doses to cover, at most, 230 million adults by the end of May. 

If side effects occur, government experts are concerned that doctors will not have the proper training to spot or treat the rare blood clots. These clots should not be treated with the standard treatment. 

The CDC and FDA recommend that people who have received the J&J vaccine within the past month contact their doctors if they experience severe headaches, abdominal or leg pain, or shortness of breath. 

Officials have said that the most common symptom of the disorder was a persistent headache that begins six days or later after being vaccinated.