The frequency of allergic reactions to Pfizer’s coronavirus vaccine is greater than earlier expected said a United States official.

In an interview with CNN, Dr Moncef Slaoui, chief scientific adviser for Operation Warp Speed said: “That frequency, as it stood yesterday (December 22), is superior to what one would expect with other vaccines.”

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This comes as The Medicines and Healthcare products Regulatory Agency (MHRA) issued precautionary advice to the National Health Service (NHS) after two healthcare staff reported allergic reactions.

Meanwhile, the US on Wednesday signed a deal with Pfizer Inc. for an additional 100 million doses of its Covid-19 vaccine.