New combination vaccine shows promising results as the US imposes stricter measures
A new study reveals that a combined mRNA vaccine for Covid-19 and influenza is highly effective. At the same time, the US is moving towards stricter regulations.
The head of the Food and Drug Administration (FDA), Martin Makary, at a press conference with Donald Trump on May 12, 2025.(Photo: Nathan Howard / Reuters / NTB)
Administering both vaccines at once is a sensible approach, says Even Fossum at the Norwegian Institute of Public Health.
"Respiratory viruses tend to circulate more in the winter months. So it's practical to offer a single vaccine in the autumn that provides protection against multiple respiratory viruses," says the researcher from the virology department.
Measured antibodies in the blood
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More than 8,000 participants over the age of 50 took part in the study.
Half received two separate shots: a traditional flu vaccine in one arm and Moderna's Covid vaccine in the other.
The remaining participants received the combination vaccine.
To ensure no one knew which group they belonged to, the researchers also gave them a saline injection in the other arm.
Researchers then measured the amount of antibodies circulating in the participants’ blood 29 days later.
The results are promising.
The dual vaccine triggered antibody levels equal to or greater than those triggered by the two individual vaccines.
Can be produced faster
The next step is real-wrold testing.
Only then will Moderna know whether the combined vaccine offers the same level of protection as the individual shots currently in use.
If it does, the combination vaccine could offer more advantages than just reducing the number of injections.
The reason is that Moderna has used mRNA technology.
Such vaccines, which saw a major breakthrough during the pandemic, can be produced faster than conventional flu vaccines.
That's a significant advantage.
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Current flu vaccines are grown in chicken eggs. This not only requires an enormous number of eggs, but the production also takes a long time.
"The problem with this method is that the flu virus constantly changes. So last year’s vaccines may not work as well against this year’s variants," says Fossum.
Even Fossum studies antibodies in the blood following vaccination and infection with influenza and Covid-19 at the Norwegian Institute of Public Health.(Photo: Eldrid Borgan)
Locked in once production begins
Still, there is no guarantee that mRNA vaccines will always be better matched to circulating influenza strains than current flu vaccines, Fossum notes.
"These vaccines have to be manufactures in large quantities. You can wait a bit longer before starting production, which gives you a better overview of the most recent virus strains. But once production begins, you're pretty much locked into the virus strains you've chosen," he explains.
Any modifications to the vaccine must also be approved, which adds more time to the process.
In the US, this process is about to become even more complicated.
Stricter requirements
The US Food and Drug Administration (FDA) has issued new guidelines for updating Covid-19 vaccines.
From now on, new Covid vaccines must be tested against a placebo before being offered to healthy children and adults.
Until now, only completely new vaccines had to be tested against a placebo – such as the very first Covid-19 vaccines introduced at the beginning of the pandemic.
High-risk groups will still have access
Makary and Prasad from the FDA explain the reasoning behind the change:
'We simply don’t know whether a healthy 52-year-old woman with a normal BMI who has had Covid-19 three times and has received six previous doses of a Covid-19 vaccine will benefit from the seventh dose,' they write in the article.
They argue that the new guidelines will drive the collection of much-needed data.
For now, it appears that high-risk groups in the US will still have access to the updated vaccines without the need for placebo-controlled trials.
"Refreshing"
Reactions to the shift in policy are mixed.
Until now, the entire American population has been encouraged to get a booster shot every year.
This sets the US apart from many other countries, including Norway, where only high-risk groups are still advised to get additional doses.
"I find it refreshing to see the clarity in these guidelines," Rick Bright, a former federal vaccine official, says in an interview with NPR.
Paul Offit, director of the Vaccine Education Center at the Children's Hospital of Pennsylvania, is critical of the decision to limit vaccine access for healthy children and adults.
The new guidelines come in the wake of Health Secretary Robert F. Kennedy Jr.'s announcement that "all new vaccines" must be tested against a placebo.
If this includes updated versions of existing vaccines, experts warn it could lead to significant delays in production.
It's "unethical," Offit stated before the new Covid vaccine guidelines were published.
To NBC News, he notes that 'it’s generally frowned upon in the scientific community to give someone a placebo when an approved product already exists that can protect them.'
May impact the vaccine market
In Norway, the FDA’s decisions do not apply. Instead, regulations are guided by national policies and the European Medicines Agency (EMA), explains Even Fossum.
"Of course, it could affect how attractive it is to develop vaccines, because it's a large market. But when it comes to how the US sets its approval standards, that’s ultimately their decision," he says.
