Experts raise safety concerns over Moderna’s 410,000 elderly COVID-Flu vaccine trials

Scientists and physicians critical of mRNA vaccines have raised concerns over Moderna’s planned clinical trial of its combined COVID-19 and influenza vaccine, warning that the study could expose a large number of older adults to serious adverse events.

The DAN-COMBO trial is expected to enrol about 410,000 healthy Danish adults aged 65 and above, with the study scheduled to take place in Denmark and Spain through the next cold-and-flu season.

The trial will compare Moderna’s mRNA-1083 combination vaccine with two separate injections — Moderna’s Spikevax COVID-19 vaccine and its mRNA-1010 flu vaccine.

Researchers say the study is intended to address gaps in evidence about the effectiveness of combining COVID-19 and influenza vaccination compared with administering the vaccines separately.

However, critics have questioned the trial’s methodology, including its lack of a placebo group and the decision not to blind participants to which vaccines they receive.

French physician and scientist Jeanne Rungby, whose analysis was published by the World Council for Health Scandinavia, said the design could introduce bias because participants’ responses may be influenced by their knowledge of which vaccine they received.

Internal medicine physician Meryl Nass also questioned the use of Moderna’s high-dose mRNA-1010 flu vaccine as part of the comparison group, arguing that its reported side-effect profile could influence the results.

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Moderna’s mRNA-1010 has itself faced regulatory scrutiny. In February, the U.S. Food and Drug Administration initially declined to review the company’s application, citing concerns about the adequacy and control of its clinical trial. The agency later agreed to review the application.

The vaccine subsequently received FDA approval for adults aged 50 to 64 and accelerated approval for those aged 65 and older.

Critics continue to dispute the safety data. Karl Jablonowski, a researcher with Children’s Health Defense, cited clinical-trial data that he said showed higher rates of adverse and serious adverse events among participants receiving mRNA-1010 compared with control groups.

Other researchers, including French scientist Hélène Banoun, have pointed to reports of myocarditis, thrombocytopenia, hypotension and other serious events following vaccination. They caution, however, that adverse events reported after vaccination do not by themselves establish that a vaccine caused those events.

Concerns have also been raised about Moderna’s mRNA-1083 combination vaccine. Jablonowski said earlier trial data involving participants aged 65 and above showed a higher rate of serious adverse events among those who received the combination vaccine than among controls.

The concerns come after Moderna withdrew its U.S. application for mRNA-1083, although the European Medicines Agency subsequently approved the combination vaccine for people aged 50 and older.

Moderna has not indicated that the DAN-COMBO trial is unsafe, and the study is intended to generate additional comparative evidence on the combined vaccine.

The debate comes amid wider disagreements over the safety, effectiveness and regulatory assessment of mRNA vaccines, with proponents pointing to their demonstrated ability to stimulate immune responses while critics continue to call for additional safety monitoring and independent scrutiny.