Covid vaccines made by Moderna and Novavax will be added to a mix and match trial

Coronavirus vaccines made by Moderna and Novavax will be added to a ‘mix and match’ trial, scientists said today.

The UK medical regulator currently requires everyone to receive two doses of the same shot: AstraZeneca, Pfizer or Moderna.

But Oxford University experts are testing whether alternating second doses can cause a stronger immune response.

In their trial – which could revolutionize Britain’s rollout – the effects of combining doses of AstraZeneca and Pfizer have already been assessed.

An additional 1,000 volunteers will now be recruited into the study to test combinations, including vaccines made by Moderna and Novavax.

Experts say mixing shots is unlikely to pose any safety concerns and predict that it could make shots even more effective at preventing infection with the virus.

In the wake of AstraZeneca’s fear of blood clots, France approved an alternative second dose. Germany did the same for young people under 60.

But until evidence is gathered, they can’t say for sure if it works or if it’s safe.

Britain has only recommended that young people under 30 get an alternative and that anyone who has already had their first dose should come forward for their second, unless they have contracted the extremely rare complication.

The Oxford mix-and-match trial was first launched in February to investigate whether alternating doses of the Pfizer and AstraZeneca vaccines increased efficacy.

The Com-COV studies, or comparing Covid Vaccine Schedule Combinations, are the first in the world to look at mixing coronavirus shots.

There are already 800 participants, who alternated between AstraZeneca and Pfizer vaccines.

But the new trial will recruit an additional 175 volunteers in each of the six arms, bringing the total number of volunteers to nearly 2,000.

Participants will be randomly assigned a Moderna or Novavax shot – which will be stamped by regulators in the coming weeks – as a second dose, eight weeks after receiving the AstraZeneca or Pfizer vaccine.

Some participants will be given the same shot as the first time as a “control” for the study, to indicate whether varying doses of jabs made it more potent.

The results will also be compared to the efficacy figures for each shot from large-scale clinical trials.

Experts will start recruiting volunteers starting Monday, but final results are expected by the end of next month at the earliest, and possibly not until July.

Their findings will be submitted to the Joint Vaccination and Immunization Committee (JCVI), which will decide whether to allow alternative doses.

The group of top scientists was also responsible for designing the jab priority list and the decision to extend the gap between jabs to 12 weeks in order to protect as many people as possible as soon as possible.

The study does not include the Johnson and Johnson jab that is expected to be approved within days, as it requires only one dose.

Professor Matthew Snape, who is leading the study, said it could provide ministers with an alternative in case a shot faces supply constraints or concerns about blood clots.

“The reason we’re doing this research is that we don’t know the effect of mixing,” he told a press conference.

‘The risk of mixing is that you will see suboptimal immune responses, or a response that is not as good as with the original vaccination course.

“I would personally be surprised if that were the case, we just don’t know what the outcome will be yet.”

He said mixing jabs could make more participants immune to infections from the virus compared to current jabs, as it can stimulate the body to attack the entire virus rather than just the spike protein – that it uses to invade cells.

Studies have suggested that the South African and Brazilian variants can partially bypass jab-induced immunity because they have distorted peaks to which antibodies are difficult to bind.

But if the immune system were to attack the entire virus, these changes wouldn’t help the virus slip in unnoticed and cause an infection.

Experts believe the current crop of injections protects against the virus, because antibodies are not the only part of the immune system.

AstraZeneca’s vaccine was 76 percent effective in blocking symptomatic Covid infections in clinical trials, compared to 92 percent for Moderna and 95 percent for Pfizer.

But experts point out that these results are “very good” for any vaccine, adding that the World Health Organization has only set the bar at 50 percent and that annual flu shots are often only about 40 percent effective.

The AstraZeneca and Novavax vaccine uses a cold-modified virus containing Covid spike proteins to teach the immune system how to fight the disease.

While Pfizer and Moderna’s jab uses mRNA – protein building instructions – to trigger the production of the spike particle.

It comes after more than 800 people enrolled in trials to find out if it was possible to ‘mix and match’ the AstraZeneca and Pfizer jabs.

All participants are over 50 and received the injections at eight locations in England, including London, Birmingham and Liverpool.

The study will last 13 months and patients will be recruited in February.