CAPITAL REGION, N.Y. (NEWS10) — “You have to always weigh the benefit and the risks,” says Dr. Edward Walsh, Professor of Medicine at the University of Rochester and Head of Infectious Diseases at Rochester General Hospital where he lead a study on the Pfizer vaccine.

Dr. Walsh says the number of cases of a rare form of blood clotting apparently involving the Johnson & Johnson COVID-19 vaccine are very small, basically one in a million.

“Clearly, the risk of dying from COVID far exceeds the risk of dying, say, from of one of these very rare, one in a million events. But it still raises concerns.”

Those concerns have elevated after one woman in the U.S. has died from the complications. All six cases in the United States are said to have occurred in women ages 18 to 48 with their symptoms developing 6 to 13 days after receiving the shot.

The symptoms have been primarily severe headache and abdominal pain.

But Dr. Walsh says individuals who were vaccinated several months ago would appear to be at little risk.

“I think the main reason to avoid too much distress is the rarity of this event,” he added.

But, with some people already hesitant to get a vaccine, does Walsh believe this recent news could convince more people to refuse the shot?

“I think it probably will. I think I would be wrong in saying that this would not,” said Dr. Walsh.

Both the Johnson & Johnson and AstraZeneca vaccines use a similar technology and have both been linked to cases of the rare disorder. The Pfizer and Moderna vaccines have not.

Dr. Walsh said more needs to be examined with regards to gender and age if the Johnson & Johnson vaccine is to be used in the future.

He says putting the vaccine on pause is a prudent move but added that it should not be a reason to forego getting a COVID-19 vaccine.

“This is a lethal viral infection. We are clearly not out of the woods by any stretch of the imagination.”