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Combination COVID-19/flu vaccines are being tested, with Moderna starting phase 3 trials


Key points:

  • Moderna is just one pharmaceutical company currently developing a combination COVID-19/influenza vaccine

  • The earliest we could expect one of these vaccines to be approved in Australia is 2025

  • Combination COVID/influenza/RSV vaccines are also in development

A combination COVID-19 and influenza vaccine developed by Moderna is a step closer to approval after early clinical trials proved successful, the pharmaceutical company reported this week.

The vaccine, called mRNA-1083, is one of several COVID-19/influenza vaccines currently in development, with pharmaceutical companies Pfizer and Novavax also conducting clinical trials with their own versions.

In a press release, Moderna said its combined phase 1 and 2 trials evaluated the safety and efficacy of their COVID/influenza vaccine when compared to:

  • a dose of influenza vaccine Fluarix for adults between 50 and 64 years of age

  • a dose of enhanced influenza vaccine, Fluzone HD, in adults 65 to 70 years of age

  • the Spikevax booster (Moderna’s COVID-19 vaccine) for both age groups

The vaccine was found safe, according to the company’s statement, with only around four per cent of trial participants experiencing “grade three adverse reactions”, which are “medically significant” but not life-threatening.

mRNA-1083 didn’t cause any new reactions that weren’t already linked to Flurarix, Fluzone or Spikevax, and provided similar or greater viral protection from influenza and COVID-19, according to Moderna.

The company says it plans to begin phase 3 trials soon in adults aged 50 and over, and is hoping for regulatory approval in the US in 2025.

Director of infectious diseases at Mater Health Services Paul Griffin said it was important to await peer review of the findings but early results appeared promising.

“Their combined mRNA vaccine had a similar safety profile and similar levels of efficacy [to current standalone vaccines], which is obviously very positive news.”

He said when developing combination vaccines, it is important to ensure the protection offered by one vaccine isn’t diminished by the other.

“This trial has established that’s not the case, so it really paves the way for the combined vaccine to continue progressing.”

Phase 3 will show vaccine effectiveness

Dr Griffin said early-stage clinical trials focused on safety and ensuring the vaccine generated sufficient levels of antibodies.

“But we can’t say that absolutely translates into good levels of protection.

“That will need to be demonstrated in phase 3, which we expect to be the case.”

Dr Griffin has been working on clinical trials of Novavax’s combination COVID-19/influenza vaccine, and says phase 3 testing is underway after they too saw promising early results.

Novavax’s vaccine differs to Moderna’s and Pfizer’s as it is protein-based, which means a form of a virus spike protein is injected into the body, leading to the production of antibodies.

Moderna and Pfizer are making mRNA vaccines. They use strands of genetic code to tell the body to construct spike proteins, which then elicit an immune response.

Adding RSV to the mix

Dr Griffin says because Pfizer, Moderna and Novavax have all demonstrated their COVID-19 vaccines are “adaptable” to a combination vaccine, he expects more COVID-19/influenza vaccines will be made by other pharmaceutical companies.

“They will be very impactful.”

But he’s most excited about a combination COVID-19/influenza/RSV vaccine, which he is also trialling with Novavax.

RSV — respiratory syncytial virus — is a common and highly contagious respiratory virus that usually causes mild, cold-like symptoms.

“We haven’t had an RSV vaccine until very recently in some parts of the world,” Dr Griffin said.

“Being able to combine all that into one vaccine is going to make a huge difference, I think.”

There is one limitation with combination vaccines though — the viruses they cover don’t necessarily peak at the same time of year.

“COVID is yet to become seasonal so the optimum timing of these combined vaccines is something that will have to be carefully thought through,” Dr Griffin said.

“But, on balance, I think this limitation is outweighed by increasing the overall rate of uptake of these vaccines.”

Clinical trial stages

  • Pre-clinical: Testing in animals. Does the vaccine produce antibodies? Does it protect against illness? What dose is necessary?

  • Phase 1: Testing in a small number of humans. This phase is about making sure the vaccine is safe.

  • Phase 2: More testing in humans — does the vaccine actually work?

  • Phase 3: Testing in a larger number of humans to confirm its effectiveness.

  • Phase 4: After the vaccine has been rolled out, ongoing surveillance to make sure it’s safe in the long term.

Combo vaccines will make getting vaccinated easier

Many Australians have fallen behind on their COVID-19 immunisations, according to the Australian Technical Advisory Group on Immunisation (ATAGI).

Last month, it reported only 53 per cent of people aged 65 years and older received a booster dose in the past six months.

ATAGI recommends that all adults aged 75 years and over should receive an additional booster if six months have passed since their most recent dose.

Dr Griffin believes combination vaccines will increase take-up as they mean one less trip to the GP or pharmacist.

“These combination vaccines will make it simpler and easier, and are certainly going to be something that helps people who are less keen on getting multiple injections.”

He believes the earliest Australia will see COVID-19/influenza combination vaccines would be 2025, but this is dependent on successful outcomes in upcoming clinical trials.

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