Other than the one who had a history of vaccine allergic reactions, none of them had experienced such reactions in the past.
The agency to consult doctors before getting inoculated.
However, the CDC said that people with a general history of allergies may still be vaccinated. However, the agency said that people with severe allergies to food, pets, latex or environmental conditions as well as people with allergies to oral medication or a family history of severe allergic reactions could still get vaccinated.
It also says that it received a report that six people who had been given the shot by Friday showed anaphylactic reactions.
According to Fox News, there have been six allergic reactions after an inoculation among 272,000 shots given to date.
The CDC further said that individuals with a history of "severe allergic reactions" will be monitored for 30 minutes after receiving the vaccine.
The US drug regulator is probing around five allergic reactions that happened after people were administered the Pfizer Covid-19 vaccine in the United States this week. It defined "severe" as a reaction requiring the medication epinephrine or treatment in a hospital.
UPS and FedEx trucks stocked with the vaccine were reportedly seen leaving McKesson's distribution centers in MS and Kentucky early Sunday afternoon.
Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said at a press conference that experts were not sure what had caused the allergic reactions, but identified polyethylene glycol as the potential "culprit". He was speaking to local broadcaster KBS, saying that the vaccine made by AstraZeneca will be available no later than March, but those from Pfizer, Janssen and Moderna might not be available by then.