British regulators have issued a warning about allergic reaction to the world-first coronavirus vaccine.

It came as the Pfizer jab was approved in Canada, and the US was poised to also give it the green light.

Two health workers who were inoculated on day one of Britain’s mass vaccination program on Tuesday (local time) suffered an anaphylactoid reaction but recovered soon after.

Both had a significant history of allergic responses to the extent they needed to carry an adrenaline auto-injector.

Britain’s Medicines and Healthcare products Regulatory Agency has given precautionary advice that anyone with history of “significant” allergic reactions to medicines, food or vaccines should not receive the jab.

This means that anyone scheduled to receive the jab on Wednesday (local time) would be asked about their history of allergic reactions.

“As is common with new vaccines, the MHRA have advised on a precautionary basis that people with a significant history of allergic reactions do not receive this vaccination after two people with a history of significant allergic reactions responded adversely yesterday,” NHS national medical director Professor Stephen Powis said.

“Both are recovering well.”

Pfizer said the vaccine was “well tolerated” during trials with “no serious safety concerns”.

“Pfizer and BioNTech are supporting the MHRA in the investigation,” it said.

“In the pivotal phase three clinical trial, this vaccine was generally well tolerated with no serious safety concerns reported by the independent data monitoring committee.”

Tweet from @JustinTrudeau

Canada and US next in line for Pfizer vaccine

Canada has become the second country to approve the Pfizer-BioNTech vaccine that Britain is already using.

Canada has ordered the highest number of doses per capita of any nation in the world.

Meanwhile the US Food and Drug Administration has raised no safety concerns in its analysis of the vaccine, paving the way for imminent approval in America.

Canada will recieve its first doses of Pfizer’s vaccine before the end of December, Prime Minister Justin Trudeau said.

The country, with a population of 38 million, has a firm order for 20 million doses of the vaccine (enough to inoculate 10 million people). It has options to buy up to 56 million more.

“The approval of the vaccine is supported by evidence that it is safe, effective and of good quality,” Health Canada said.

The vaccine has initially been authorised for use in people aged 16 and older.

Pfizer is responsible for shipping its vaccine, which requires ultra-cold storage, to warehouses across Canada.

According to preliminary guidance published by the Canadian government in early November, vulnerable people and those who look after them are high priority. They include long-term care residents and some healthcare workers.

-with AAP