Regulators in the United Kingdom have warned that people with a history of a significant allergic reaction should not receive doses of the Pfizer and BioNTech COVID-19 vaccine, according to a BBC report.

People across the country are set to receive COVID-19 vaccine shots as a mass vaccination programme gets underway, in a historic moment dubbed ‘V Day’.

Britain last week became the first country in the world to approve the Pfizer/BioNTech vaccine. This will be the NHS’s biggest and most highly anticipated immunisation campaign in history.

The latest recommendation by the Medicines and Healthcare products Regulatory Agency applies to those who have had reactions to medicines, food or vaccines, the BBC report said.

The two NHS workers are believed to have had an anaphylactoid reaction which involves skin rashes, breathlessness, and occasionally a drop in blood pressure. This is not understood to be fatal like anaphylaxis.

According to Professor Stephen Powis, medical director for the NHS in England, the workers are recovering well. He said, quoted the BBC,

Dr June Raine, head of the MHRA, said it was only right to take this step now that "we've had this experience".

Prof Peter Openshaw, an expert in immunology at Imperial College London, said: "The fact that we know so soon about these two allergic reactions and that the regulator has acted on this to issue precautionary advice shows that this monitoring system is working well."

(With inputs from BBC)