One of Public Health England’s (PHE) top officials has said the body does not recommend mixing Covid-19 vaccines from different suppliers, despite recent government guidance stating it would be “reasonable” to do so if necessary .
Dr Mary Ramsay, head of immunisations at PHE, told Sky News on Saturday that the mixing of vaccines – for example, giving one dose of the Pfizer/BioNTech vaccine followed by the Oxford-AstraZeneca vaccine – should only be done on “rare occasions”.
Both vaccines require two doses to maximise effectiveness. On New Year’s Eve, the government issued guidance to healthcare workers stating that “every effort should be made to determine which vaccine the individual received and to complete with the same vaccine”.
But concerns have been raised about another part of the guidance, which says that if a patient came back for a second dose but the same type of vaccine as their first jab was not available or it was unclear what type the patient had previous recieved, it would be “reasonable” to use a different type of vaccine, particularly if an individual is deemed particularly high risk.
The Pfizer/BioNTech vaccine was approved first by UK regulators, but supplies of the jab are much more limited than the Oxford-AstraZeneca vaccine, which was trialled and developed in the UK.
Around two million doses of the Oxford-AstraZeneca vaccine are reportedly expected to be manufactured every week by the middle of January, it was revealed on Friday.
Ramsay told Sky News: “We do not recommend mixing the Covid-19 vaccines - if your first dose is the Pfizer vaccine you should not be given the AstraZeneca vaccine for your second dose and vice versa,” she said.
“There may be extremely rare occasions where the same vaccine is not available, or where it is not known what vaccine the patient received.
“Every effort should be made to give them the same vaccine, but where this is not possible it is better to give a second dose of another vaccine than not at all.”
Ramsay’s recommendation echoed that of Professor Sir Munir Pirmohamed, chairman of the Commission on Human Medicines expert working group on Covid-19 vaccines, who advised that vaccines should not be mixed on Wednesday.
He said: “We’re not advising mixing doses of different vaccines because we don’t have any data on that. Our advice is that if you have the Pfizer vaccine as the first dose, the second dose should also be the Pfizer vaccine.
“If you have the AstraZeneca vaccine as the first dose, the second dose should also be the AstraZeneca vaccine.
“There are trials which are being planned where different people will receive different vaccines at different time points and that may provide us more data as to whether you can mix the vaccines.”
Questions have been raised about the risks of mixing vaccines, with the New York Times reporting that experts had voiced concerns due to the lack of data available on the results of using two jabs for one patient.
However the report has been criticised by some experts, who say the government guidance on mixing vaccines was clearly intended to apply to a limited number of patients, and not an endorsement of widespread vaccine mixing.