Moderna is banking on a combined COVID, flu and RSV vaccine. Will it work?

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• Moderna is developing a three-in-one vaccine against COVID-19, flu and RSV.

• The vaccine manufacturer is actively promoting the shot and hoping for regulatory approval in the next year.

• But without solid safety and efficacy data from clinical trials, it may never come to fruition.

Moderna is actively promoting a combined COVID-19, flu and RSV vaccine, something that aims to target three of the most serious respiratory illnesses circulating each year in a single shot.

But while a safe and effective vaccine would be welcome as Canada faces a surge in pediatric RSV cases, stubbornly high COVID hospitalizations and deaths and steeply rising flu cases, the pharmaceutical company hasn't released data to support the vaccine's safety or efficacy.

Moderna president Stephen Hoge told CBC News he hoped the three-in-one vaccine would be submitted to Health Canada for regulatory approval within a year.

"We really do think that the triple combo the flu, plus COVID, plus RSV is really going to be the ideal shot for us to get every year," he said in an interview this week.

"And honestly it just takes one shot to try and prevent all of that, and so we'll try and add as much bang for the buck into that shot as we can and hopefully help protect people through winter seasons in the years to come."

'More questions than answers'

But without solid data from clinical trials this combined vaccine may never come to fruition.

Moderna's decision to promote its vaccine before completing Phase 3 clinical trials in which the vaccine would be tested on a larger group as part of a randomized, double-blind study is controversial. It's also raised concerns from vaccine researchers and infectious diseases experts about the motivations behind prematurely marketing the shot.

"There's still more questions than answers, obviously, with releases like this that come from companies without accompanying data," said Matthew Miller, a vaccine researcher and associate professor of infectious diseases and immunology at McMaster University.

"I think we need to be really cautious. We have no data on safety, no data on effectiveness or efficacy or age groups. How would you handle updating various components of that vaccine? Lots and lots of questions."

Alyson Kelvin, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan, said that while the flexibility of mRNA technology for future vaccines is "exciting," it's essential to see safety and efficacy data from clinical trials.

"What is it claiming to do? Is it claiming to reduce disease, or block infectionor reduce hospitalization? And is it effective in what it's saying it's supposed to do?" she said. "It's always best to have the data to back up your claims."

Dr. Isaac Bogoch, an infectious diseases physician at Toronto General Hospital and member of Ontario's COVID-19 vaccine task force, said it's not yet known what level of protection an RSV vaccine would provide or how frequently shots would be needed.

"I would be very careful now to assume that making a three-in-one vaccine that's administered annually is needed," he said. "Clearly, we need vaccines for all three, but we don't know what the frequency of vaccination is going to be."

Health Canada said in a statement to CBC News it would only authorize new vaccines if the independent and thorough scientific review of all data included in the submission showed that the benefits of the vaccine outweighed the potential risks for the Canadian population.

Hoge said Moderna is also developing standalone RSV and flu vaccines, a combination COVID and flu shot and a combined COVID and RSV shot all of which are still in clinical trials.

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The Ontario Medical Association is urging people to wear masks indoors and get their flu and COVID-19 shots as concern builds that a spike in flu cases could overwhelm a health-care system already seeing an influx of RSV and COVID patients.

"We've got all kinds of combinations, all in clinical trials," he said. "Beyond that, we're actually expanding into a range of other viral infections."

Hoge said the biotechnology company hopes to use the mRNA platform to develop vaccines that target viruses that cause certain types of cancer, multiple sclerosis and birth defects, among others in addition to developing treatments for cancer and some rare diseases.

But while it all sounds promising, Moderna's claims should be taken with a grain of salt until there is concrete data to back them up.

Lower COVID vaccine uptake in past 6 months

Pharmaceutical companies typically wait until Phase 3 trials are finished before actively promoting their products in the media, but the urgent need for vaccines and treatments in the pandemic has accelerated the controversial strategy of science by press release.

Moderna's comments come just days after Pfizer announced Phase 3 clinical trial results for its RSV vaccine in a press release, which suggested the shot was 81.8 per cent effective in infants from birth to the first 90 days of life and remained almost 70 per cent at six months.

It also comes after the company's stock price dropped close to 30 per cent since January following weaker-than-expected third-quarter earnings and a decline in COVID-19 vaccine uptake in Canada and around the world.

Fewer than one in five Canadians have gotten a booster or completed an initial vaccine series in the last six months, though more than 84 per cent of Canadian five and older have received at least two doses. But for kids under five, fewer than seven per cent have received one dose of vaccine while just one per cent have received two doses.

"It's obviously tremendously concerning and disappointing because there still are large numbers of hospitalizations and deaths among Canadians as a result of the virus and these are preventable really with boosters and vaccines," Hoge said.

"I do hope that over time, as we kind of work through the pandemic phase and into the endemic phase, [prevention] becomes something people are more used to and normally accept."

But it's important to note that Moderna is still a for-profit company selling a product to consumers, with Hoge reportedly cashing out more than $165 US million in stock options last year on top of his $18.2 US million salary over 40 per cent higher than in 2020.

Challenges with developing vaccine

Developing a vaccine for RSV, let alone combining one with COVID and flu, is no small feat and the complications around dosing, timing and age considerations could pose major challenges for the vaccine maker down the road.

"Having a single formulation increases the complexity of updating that formulation annually," said Miller, at McMaster University in Hamilton.

"So now, instead of dealing with four flu strains, you're adding in RSV and COVID and having a combined shot might actually be more complex in some ways than having separate formulations that are co-administered at the same time."

Miller said it's also unknown if getting one combined shot would be as effective as multiple shots and what age groups would be most appropriate for an RSV vaccine given that adults under 65 don't tend to experience severe disease from it like infants and the elderly do.

"It's not as simple as just saying, 'Let's just vaccinate everybody once a year with this' and so I don't think that having a combined vaccine is going to be a panacea," he said.

"There are differences both in conventional flu vaccines and in mRNA-based COVID vaccines in doses. Elderly people benefit from higher doses, we have other doses for adults, we have other doses for children so there's a lot of nuance and complexity."

Kelvin said that while it's true RSV might be inconsequential to healthy adults in terms of severity of disease, they are still part of the transmission chain that affects vulnerable infants and seniors.

"It's important that everyone else who can be infected and transmit the virus is addressing that they're a link in the transmission chain," the virologist said. "And being protected will help stop the virus from infecting vulnerable people."

Bogoch said that while there's nothing inherently wrong with combining multiple targets into one vaccine, it's important to prove that strategy is safe and effective before pharmaceutical companies start bundling them together and promoting an annual shot.

"Look, we have measles mumps and rubella, diphtheria, tetanus, and pertussis like this is fantastic. Fewer needles, greater uptake it's remarkable," he said.

"The real issue here is we don't know what the future lies for with regards to COVID-19 booster vaccines, and even less we know about RSV."

Previous attempts at an RSV vaccine have proved disastrous in the past, when two infants died in the 1960s after experiencing severe lung inflammation during their first RSV infection following vaccination.

Though concerns over the early vaccine slowed development of others for RSV, the World Health Organization said that recent advances in the understanding of the biology of the virus have led to the clinical development of several potential vaccines though none have yet received regulatory approval.

While the mRNA vaccine technology has saved countless lives around the world from COVID during the pandemic and succeeded at keeping many Canadians out of hospital, it will take time to see whether the platform is as successful with other viruses.

"It is great that we have this brand-new vaccine platform that's really flexible and can be deployed quite readily against multiple classes of pathogens," said Miller.

"But we still need to see data, we still need to see the vaccine's effectiveness, we need to see that the safety profile is acceptable and we need to understand things about doses and frequency of boosters."