Delaying the second dose of Novavax’s Covid vaccine by up to 12 weeks should be ‘fine’

Professor Paul Heath said a 12-week dosing gap would most likely not make the Novavax jab less effective

Novavax’s Covid vaccine will ‘probably’ still be effective if the second dose is delayed by up to 12 weeks, according to one of the firm’s top scientists. 

Professor Paul Heath argued that ‘basic immunological principles’ suggested the longer gap would not make the jab — up to 90 per cent effective at preventing Covid symptoms in trials — any less potent.

But he warned there was no data to prove this because trial participants received their second dose four weeks after their first.

Britain’s regulator is set to rubber-stamp the jab — already being manufactured in Stockton-on-Tees — within the next four weeks, Professor Heath added.

They are expected to triple its dosing gap to 12 weeks – as with AstraZeneca and Pfizer jabs – so that the most Britons can be reached in the shortest time possible. 

Official data already suggests the two jabs provide just as good protection after the 12 week delay, despite this not being tested in clinical trials.

Boris Johnson revealed last night that Britain’s 60million Novavax doses will now be packaged at a GlaxoSmithKline factory in Durham amid sabre-rattling from Brussels.

Ministers had initially planned to send them to Europe for ‘fill and finish’, when the precious fluid is put into vials, but the change means they now will not leave the UK.

Novavax is due to submit its late stage trial data to Britain’s medical regulator in the coming weeks and approval is expected in May. It will likely become the fifth Covid jab to be approved in the UK, as Johnson and Johnson’s one-dose jab is already under review. 

Boris Johnson revealed yesterday that the jabs will now be packaged at a factory in Durham, after it was initially planned for them to be sent to the EU

Boris Johnson yesterday revealed the British drugs giant GlaxoSmithKline will support the manufacturing of up to 60million doses of the Novavax vaccine in the UK

Professor Heath, who is also the director of the vaccines institute at St George’s, University of London, said it would be ‘fine’ if the gap between doses was widened.

‘The answer is we don’t know because we haven’t looked at studies where the two doses have been separated by more than three to four weeks,’ he told Sky News.

‘(But) from basic immunological principles I think it probably would be.’

He added: ‘We know from other vaccines that we can extend the interval between doses and do so with confidence.

‘So if we needed to for this vaccine, I’m sure extending that interval would be fine from the point of view of its effectiveness.’

The Novavax jab teaches the immune system to make antibodies against Covid’s spike protein – which it uses to invade cells. 

It contains miniscule replicas of the spike protein – made from tiny nanoparticles – which, when injected into the body, trigger an immune response.

This means that should someone encounter Covid in the future, their body is primed to fend it off.

Trials showed it was 89.3 per cent effective at stopping symptomatic Covid infections in volunteers in the trials.

It was also 60 per cent effective against the South African variant, which scientists are worried could dodge vaccine-triggered immunity and cause a third wave.

But experts working on the trial said this was a ‘good result’ and showed other jabs would also likely offer some protection against this variant.

They pointed out too  

Mr Johnson said yesterday the decision to get GlaxoSmithKline to package the Novavax jabs will ‘further boost our vaccine roll-out’.

‘I’m delighted by GSK’s investment, which shows the strength of UK manufacturing, and will further boost our vaccine rollout,’ he told a Downing Street press conference yesterday.

‘The vaccines taskforce has worked hand in glove with business to successfully deliver vaccines to the whole of the UK and this agreement will continue to support our approach.

‘We remain on track to offer a first jab to all over-50s by April 15, and all adults by the end of July, and I want to once again encourage everyone to come forward for a vaccine when you’re called.’

Britain already has enough doses on order from AstraZeneca and Pfizer alone to vaccinate the entire nation with two doses. 

But officials anticipate ‘booster’ shots will need to be given annually to the elderly and vulnerable because immunity wears off quicker in those groups.