Johnson & Johnson recently issued a media statement saying that said a study showed there were reports of blood clots with other Covid-19 vaccines, pointing a finger at Pfizer and Moderna's Covid-19 vaccines.
The statement comes after the US reported that Johnson & Johnson's Covid-19 vaccine might be linked to blood clots, reports the CNN.
However, according to the lead author of the study, that is not the case.
"We didn't find anyone with blood clots," Dr Eun-Ju Lee, an assistant professor of medicine at Weill Cornell Medical College, said of her study of Moderna and Pfizer's vaccines.
"We didn't find any of those scary things that are happening with Johnson & Johnson."
Among the more than 7 million people who have received the Johnson & Johnson Covid-19 vaccine, at least seven have experienced very rare blood clots in the brain.
The company came under fire for stoking fear about Pfizer and Moderna's vaccines when in fact Johnson & Johnson's shot is the only one authorised in the US with reports of blood clots.
In its media statement, Johnson & Johnson wrote there had been reports of blood clots for "all Covid-19 vaccines."
"That is a really irresponsible thing to say," said Dr Paul Offit, a vaccine expert at the University of Pennsylvania. Dr Offit is a member of the US Food and Drug Administration's advisory panel that reviewed emergency use authorisation applications from all three Covid-19 vaccine manufacturers.
He noted that the company's statement was especially unfortunate given there are still significant numbers of people in the US who are hesitant to get a Covid-19 vaccine.
"I think Paul is right on," said Dr William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, who is a member of a vaccine advisory panel to the US Centers for Disease Control and Prevention.
"His indignation is appropriate," he added.
A Johnson & Johnson said in a statement: "We continue to work closely with medical experts and global health authorities to assess the data on these extremely rare events. Above all, we are committed to the safety and well-being of the people who use our products, and we support public awareness of the signs and symptoms to ensure the correct diagnosis, appropriate treatment and expedited reporting by health care professionals."