Experts have called for robust monitoring to assess how altering the coronavirus vaccine dose schedule impacts the effectiveness of both the Oxford-AstraZeneca and Pfizer/BioNTech jab.

The British Society for Immunology said that while it would prefer the original dosing schedules – as tested in clinical trials – be followed, it accepted the rationale for the change.

Experts advising the Government, including the Joint Committee on Vaccination and Immunisation (JCVI), said the focus should be on giving at-risk people the first dose of whichever vaccine they receive, rather than providing the required two doses in as short a time as possible.

This now means the second dose of both the Oxford-AstraZeneca and the Pfizer/BioNTech vaccines will be within 12 weeks of the first.

The British Society for Immunology said that given this change in dosing schedule “deviates from its preference of a strict evidence-based approach”, it has called on the Government to ensure the following is implemented.

The society called on the Government to implement a robust programme of immune monitoring to assess how altering the dosing schedule impacts efficacy of both vaccines that have been approved for use in the UK, with rapid modification of dosing schedules as appropriate.

This should include studies from a number of sources including vaccine development teams, Public Health England, and the devolved nations to learn how the altered dosing schedule affects immune responses in the medium and longer term.

The society said it had been assured by the Government that this monitoring is in place and will be conducted.

It also called for a high-profile, multifaceted engagement programme to build public understanding and confidence in Covid-19 vaccination.

It further said there should be strong and clear messaging to the public that the highest level of protection is only gained through two doses of the vaccine.

In a statement the British Society for Immunology said that for the Pfizer/BioNTech vaccine, the immunology from preclinical to phase two trials shows that better neutralising antibodies and T cell levels are achieved after the second dose.

Similarly, the Oxford-AstraZeneca vaccine shows substantial immunological differences after the second dose at 28 days.

“The current Government policy is that the second dose should be delayed from three or four weeks to 12 weeks maximum, not that people should not receive the second dose,” the society noted.

It continues: “The exact relationship between the immunology and the disease protection data is uncertain but the chief medical officers and the JCVI have noted that, by taking all relevant issues and data into consideration, more people can be protected from symptomatic disease in the short-term by extending the second dose up to 12 weeks.

“There is also some evidence from the Oxford-AstraZeneca vaccine that this approach may be beneficial.

“There is no suggestion by the Government that the second ‘booster’ dose should be extended any longer than 12 weeks.”

However, BioNTech told the Financial Times that there is no data to support moves to delay the second dose of the jab.

While Pfizer had said it only assessed its vaccine on a two-dose regimen where people were given the jab three weeks apart, and there was “no data to demonstrate that protection after the first dose is sustained after 21 days”.

The UK’s chief medical officers have said the first Covid-19 vaccine dose offers “substantial” protection.

They strongly support the advice of the JCVI, which recommended that the focus should be on giving at-risk people the first dose of whichever vaccine they receive, rather than providing the required two doses in as short a time as possible.

Stephen Evans, professor of pharmacoepidemiology, London School of Hygiene and Tropical Medicine, said: “It is quite understandable that those vaccinated with their first dose might be anxious that they are not as protected as they might be when their second dose is delayed.

“They should understand that the first dose has an effect that will give many people complete protection over a reasonable period, certainly three months and probably a lot longer.

“The second dose will increase the numbers with complete protection and will not give extra benefit in the short term to those who already have essentially complete protection.

“Getting the second dose later is very likely to extend the duration of protection and possibly also increase the numbers who will become fully protected compared with getting the second dose at 21 days.

“This is clearly not an ideal, but realising that we are all in this pandemic together and individually doing things that benefit us all is the best way forward.”