Pfizer officials have said they saw no serious allergic reactions to its vaccine in clinical trials following news of two people reportedly experiencing a reaction after receiving the jab in the United Kingdom.

British health officials are looking into reports of two people who said they suffered an allergic reaction after receiving the vaccine on Tuesday, according to the National Health Service in England. In the meantime, it was suggested for the British public to avoid the vaccine if they suffer from severe allergies.

The incidents were acknowledged during the Food and Drug Administration’s (FDA) Vaccines and Related Biological Products Advisory Committee, an independent panel commissioned to discuss and vote on if they would support emergency use authorisation of Pfizer’s coronavirus vaccine.

Pfizer officials said they saw no serious allergic reactions among volunteers who received the vaccine in the company’s clinical trials.

“Amongst the 44,000 subjects, we saw no serious allergic reactions to the vaccine,” Dr William Gruber, senior vice president of vaccine clinical research and development at Pfizer, said.

“Within the clinical trial we've actually not seen evidence to suggest a signal related to allergic reaction to the vaccine,” he added.

Dr Gruber said the company was “conscious” of the report that occurred in the UK, but he declined to comment on it at the time.

Pfizer excluded from its clinical trial anyone who had a history of allergies such as ones related to adverse reactions associated with a vaccine. 

“The nature of what was actually excluded from the trial was really restricted to those individuals who had had a severe allergic reaction to a vaccine — any vaccine — previously, or obviously during the course of the trial if they’d gotten the first dose, and they had a significant type one hypersensitivity response, then that would preclude giving a second dose,” Dr Gruber said. 

It was added that Pfizer officials did not encounter anyone in the clinical trial who needed to be excluded from receiving the second dose.

Dr Marion Gruber – director of Office of Vaccines Research & Review at the FDA, who is unrelated to Dr William Gruber – was asked if the recent information from the UK influenced the agency’s decision issuing an emergency authorisation. The FDA conducted its own safety analysis of the Pfizer vaccine data and the potential serious side effects, she said, and the agency found no harmful health risks. 

She added the FDA was already working with Pfizer to provide a fact sheet to the prescriber that would advise on the appropriate medical treatment “in the event an acute anaphylactic reaction were to occur.”

Dr Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia, said he was worried about what this information could mean for the millions of Americans who suffer from severe allergies. 

“We don't know the details of those two cases. We don’t know specifically what it was they were allergic to, or what their history with severe allergies was,” Dr Offit said, who is a voting member of the committee. 

“There are tens of millions of people in this country who carry EpiPens with them — because they have peanut allergies, because they have egg allergies — who are going to believe now that they can't get this vaccine,” Dr Offit said. “That's a lot of people.”

“This issues is not going to die until we have better data," he added, imploring Pfizer to launch another clinical trial specifically for Americans with severe allergies. 

Other side effects people have experienced after taking Pfizer’s coronavirus vaccine include pain at injection site, headaches, fever, muscle aches, and chills.