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- Moderna’s DAN-COMBO trial will compare its mRNA-1083 COVID-flu combination vaccine with separate COVID-19 and high-dose flu shots in up to 410,000 Danish adults age 65 and older.
- Scientists and physicians critical of mRNA vaccines are raising concerns about the trial’s design, including the lack of a placebo group and the fact that participants will know which vaccines they received.
- Critics also question the use of Moderna’s high-dose mRNA-1010 flu vaccine as the comparator, arguing that its reported adverse-event profile could make the combination vaccine appear more favorable.
- The article cites clinical-trial data and analyses from critics who say mRNA-1010 was associated with higher rates of serious adverse events and deaths than comparison flu vaccines, while Moderna’s vaccine nonetheless received FDA approval in 2026.
- Critics also point to an earlier mRNA-1083 trial in which participants age 65 and older reportedly had 38% higher odds of a serious adverse event than those in the control group.
- Critics cited additional concerns about lipid nanoparticles, potential DNA contamination and vaccine effectiveness, and called for greater scrutiny of the large new trial.
Scientists and physicians critical of mRNA vaccines warn that a new clinical trial for Moderna’s combination mRNA COVID-19 and flu vaccine could expose hundreds of thousands of older adults to serious health risks, including cardiac problems, blood clots and death.
The warnings stem from concerns about adverse event data associated with the two vaccines used in the trial and the trial’s methodology.
The “DAN-COMBO” study will compare Moderna’s mRNA-1083 combination shot with two separate shots: Moderna’s Spikevax COVID-19 vaccine and its mRNA-1010 high-dose flu vaccine.
The large-scale trial, which Moderna plans to conduct in Denmark and Spain, seeks to enroll 410,000 healthy Danish adults age 65 and older. It’s scheduled to launch this month and run through next year’s cold-and-flu season.
The trial could involve up to one-third of Denmark’s 65-and-over population, according to an analysis by the World Council for Health Scandinavia.
According to the DAN-COMBO research team, the study is needed because “knowledge is still lacking” about the relative efficacy of a combination COVID-19 and flu vaccine compared with two standalone shots.
But scientists and physicians critical of mRNA vaccines have warned that Moderna’s new clinical trial could expose older adults to serious adverse events.
Brian Hooker, Ph.D., chief scientific officer of Children’s Health Defense (CHD), said the trial’s size makes it particularly concerning.
He argued that reports of cancers, cardiac problems, clotting disorders and deaths following earlier mRNA COVID-19 vaccination campaigns warrant greater scrutiny of the technology.
“This is a catastrophe in the making,” Hooker said, citing what he described as widespread adverse health outcomes following the rollout of mRNA COVID-19 vaccines, including an “uptick of cancers, cardiac issues, clotting disorders and death.”
Scientists question design of new COVID-flu vaccine trial
French physician and scientist Dr. Jeanne A. Rungby has raised several concerns about the design of the DAN-COMBO clinical trial, including the lack of a placebo group and the fact that participants will not be blinded.
Rungby’s analysis, published by the World Council for Health Scandinavia, included copies of her communications with the Moderna trial’s research team.
Under the trial design, there is no placebo group. Instead, all participants will receive either the combination vaccine or separate COVID-19 and flu shots.
Rungby also noted that participants are not blinded to which vaccines they receive.
“This gives rise to what is called bias, namely that the trial participants’ answers to questions can be influenced by their beliefs about the trial product they have received,” Rungby wrote. “A belief that can be influenced by the information from the project staff who give the vaccines.”
Internal medicine physician Dr. Meryl Nass also questioned the choice of vaccines used in the comparator group.
According to the Danish General Practitioners Vaccination Service, the high-dose mRNA-1010 flu vaccine contains four times as much inactivated flu virus antigen as a standard-dose vaccine, resulting in a stronger antibody response and better protection.
But Nass argued that using a high-dose flu vaccine as the comparator could make the combination vaccine appear more favorable.
“Moderna chose to use a high-dose flu vaccine as the comparator, because it has a much worse side effect profile than the ordinary flu shots,” Nass said.
Nass said similar comparisons were used in analyses of COVID-19 vaccines, in which vaccines with higher rates of reported side effects were used as comparators.
Rungby also questioned how clearly the trial’s recruitment materials disclose that participants will receive an mRNA vaccine.
“You have to go all the way down to the product summary” on the Danish General Practitioners Vaccination Service’s recruitment website “to get this information,” she wrote, noting that some people “want to avoid mRNA vaccines — but not traditional vaccines.”
FDA initially declined to review mRNA flu vaccine
Moderna’s mRNA-1010 flu shot didn’t clear approvals without controversy.
In February, the U.S. Food and Drug Administration (FDA) refused to review Moderna’s application for mRNA-1010, saying the company had not conducted an “adequate and well-controlled” clinical trial and had failed to use the “best-available standard of care.”
The rare refusal-to-file letter was signed by Dr. Vinay Prasad, then-director of the FDA Center for Biologics Evaluation and Research (CBER).
The FDA reversed course two weeks later and agreed to review Moderna’s application. Some observers suggested political pressure and corporate lobbying contributed to the agency’s change in direction.
The review unfolded amid significant turnover at the FDA. In April, Prasad resigned from CBER for the second time in less than a year. The following month, FDA Commissioner Marty Makary resigned amid reports that he would be fired.
In May, the agency also dismissed Tracy Beth Høeg, M.D., Ph.D., the FDA’s top drug regulator and a vocal advocate for vaccine safety.
In June, the FDA Vaccines and Related Biological Products Advisory Committee unanimously recommended approval of mRNA-1010 after reviewing Moderna’s Phase 4 clinical trial. In August, the FDA fully approved the vaccine for adults ages 50-64 and accelerated approval for adults 65 and older.
Studies link Moderna mRNA flu vaccine to high rates of adverse events
Despite the FDA’s approval, the Centers for Disease Control and Prevention has not included mRNA-1010 among its recommended shots for the current cold and flu season.
Karl Jablonowski, Ph.D., CHD’s senior research scientist, said clinical trial data for mRNA-1010 raised safety concerns.
According to Jablonowski, data published in 2025 showed a 9% increase in adverse events within 28 days, including one death, a 14% increase in serious adverse events and a 172% increase in deaths — 11 compared with four — among participants receiving mRNA-1010 versus the control group.
Later clinical trial data published in The New England Journal of Medicine also showed a statistically significant higher rate of serious adverse events among participants receiving mRNA-1010 compared with those who received a conventional flu vaccine.
French scientist and author Hélène Banoun, Ph.D., told The Defender the trial data showed a “disproportionate number of serious adverse events” — including syncope, hypotension, myocarditis and thrombocytopenia — in the first month following vaccination. Those conditions are “associated with mRNA vaccines,” she said.
“Within six months after the injections, there were 71 deaths, none of which were attributed to the vaccine,” Banoun said. She noted that 38 deaths occurred among participants who received mRNA-1010, while 33 occurred among those who received a conventional flu vaccine.
Noting that most of the deaths occurred during the first month after vaccination, Banoun said, “This supports a causal link.”
Jablonowski previously told The Defender that the clinical trial used to support mRNA-1010’s approval was flawed.
The vaccine was tested during the 2024-25 flu season, when, according to Jablonowski, Cleveland Clinic data showed available flu vaccines had negative 27% efficacy, meaning people who got the flu shot were 27% more likely to get the flu.
Jablonowski also noted that Moderna compared mRNA-1010 with a conventional flu vaccine rather than an unvaccinated control group.
In an analysis published by the World Council for Health Scandinavia, Rungby said the efficacy of Moderna’s mRNA-1010 was only 26.6%, an outcome she described as “a negative benefit/disadvantage profile.”
Dr. Angus Dalgleish, professor of oncology at City St George’s, University of London, told The Defender these outcomes should have led the FDA to reject mRNA-1010. He called the FDA’s approval of the vaccine an example of “extreme negligence.”
Moderna’s combination vaccine previously faced regulatory hurdles
The concerns about the DAN-COMBO trial also come after Moderna withdrew its U.S. application for its mRNA-1083 combination COVID-19 and flu vaccine.
Reuters reported last year that Moderna’s decision to withdraw its application was “the latest sign of increased regulatory scrutiny” of the vaccine approval process.
Despite the U.S. withdrawal, the European Medicines Agency approved Moderna’s combination shot in April for people age 50 and older.
Jablonowski said an earlier U.S. clinical trial of the mRNA-1083 combination vaccine produced concerning results.
Among participants age 65 and older, he said, those who received the mRNA combination vaccine had 38% higher odds of experiencing a serious adverse event.
According to his analysis, 71 of 2,011 mRNA-1083 recipients (3.53%) experienced serious adverse events, compared with 52 of 2,006 participants (2.59%) in the control group. There were two deaths in the mRNA-1083 group and one in the control group.
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Questions about mRNA vaccines and the new trial
Rungby also raised concerns about the composition of the mRNA vaccines used in the trial, including their lipid nanoparticles.
Lipid nanoparticles deliver mRNA to human cells, but researchers have also reported that they may deliver DNA contaminants into cells.
“There is a risk of contamination with DNA and endotoxins (parts of bacteria), which can cause serious side effects and death,” Rungby wrote.
Hooker similarly raised concerns about residual DNA in Moderna’s COVID-19 vaccine.
“We know that there are billions of contaminating DNA fragments in the original Spikevax formulation, and there is no reason to assume that there won’t be the same in the combination vaccine,” he said.
Hooker also questioned the effectiveness of COVID-19 and flu vaccines, pointing to what he described as “waning or poor” immunity.
In August, a group of physicians also asked U.S. Health Secretary Robert F. Kennedy Jr. to withdraw mRNA-1010 after their review of FDA data showed that the vaccine’s risks outweighed its benefits.
Related articles in The Defender
- Doctors Call on RFK Jr. to Withdraw Moderna mRNA Flu Vaccine After Review of FDA Data Shows Risks Outweigh Benefits
- Breaking: Moderna’s mRNA Flu Vaccine Gets Unanimous Thumbs-Up Despite Risks, Low Efficacy
- Moderna ‘Shocked’ After FDA Scuttles Review of New mRNA Flu Vaccine
- Moderna Pulls Application for FDA Approval of Flu-COVID Shot After FDA Calls for New Clinical Trials’
- Researchers Find Residual DNA in mRNA COVID Vaccines. Standard Testing Didn’t Detect It.
- ‘Deeply Concerning’: This Year’s Flu Shots Led to 27% Higher Risk of Flu
