Government study to assess routine interchangeability of Covid vaccines

The Government has launched a new study on the interchangeability of Covid vaccines with a view to making the vaccination programme ‘more flexible’.

In November, Public Health England (PHE) said that different types of Covid vaccines could be used interchangeably if giving two doses of the same version is not possible – although it said that ‘every effort’ should be made to complete both doses with the same vaccine.

The Department of Health and Social Care (DHSC) today announced that it has launched a ‘world-first’ clinical trial on ‘alternating’ vaccine doses, backed by £7m of funding.

The 13-month study will analyse whether more than 800 patients can safely be given the Oxford/AstraZeneca vaccine for their first dose and the Pfizer/BioNTech vaccine for their second, and vice versa, across eight UK sites.

The combinations will be tested at both 28 days and 12 weeks apart, alongside both doses of the same vaccine at both intervals as ‘control groups’.

However, the DHSC stressed that there are ‘no current plans’ to change the same-dose regimen and that patients who have received their first dose of either vaccine ‘will not be affected by this study’.

It added that the current 12-week interval between doses also ‘remains unchanged’.

It said: ‘Should the study show promising results, then the Government may consider reviewing the vaccine regimen approach if needed, but only if proven to be safe and recommended by the Joint Committee on Vaccination and Immunisation (JCVI).’

It comes as health secretary Matt Hancock said on Tuesday that he has a high degree’ of confidence that vaccine supplies and logistics will enable patients to receive the ‘right’ second vaccine dose at the right time.

But today, chief medical officer and senior responsible officer for the study Professor Jonathan Van-Tam said there would be ‘advantages’ to making the vaccination programme ‘more flexible’ in the face of possible vaccine shortages.

He said: ‘Given the inevitable challenges of immunising large numbers of the population against Covid-19 and potential global supply constraints, there are definite advantages to having data that could support a more flexible immunisation programme, if needed and if approved by the medicines regulator.

‘It is also even possible that by combining vaccines, the immune response could be enhanced giving even higher antibody levels that last longer; unless this is evaluated in a clinical trial we just won’t know.’

Patients aged over 50 who have not yet received their first dose will be recruited during February, with vaccinations expected to start ‘towards the middle of the month’ and initial findings to be published ‘in the summer’, the DHSC said.

In November, PHE said it was ‘likely’ that a different second dose ‘will help to boost the response to the first dose’, but it acknowledged there was ‘no evidence’ about the interchangeability of vaccine candidates and said studies were ‘underway’.