New York, Dec 11 (IANS): mRNA that are gene-based vaccines may not be a fix for all the problems with vaccine development, shows early data from clinical trials of Moderna's mRNA-based seasonal flu vaccine.

With the success of Moderna's Covid-19 vaccine, the company in July launched a clinical trial of an mRNA seasonal flu vaccine.

The results released by the drugmaker on Friday showed that the mRNA flu shots did generate antibodies, but the levels of those antibodies weren't higher than those for other flu shots already on the market. They also had more side effects than existing shots, The Verge reported.

Moderna's early data shows that "the immune system is tricky and that mRNA vaccines probably aren't an easy shortcut for stopping a virus as persistent as the flu. More studies will be needed to figure out if there is a specific benefit to using mRNA vaccines to fight the flu", chemist and writer Derek Lowe wrote in the journal Science.

The overwhelming success of the mRNA Covid-19 vaccines, made by Moderna and Pfizer/BioNTech, supercharged interest in that strategy for developing shots.

mRNA shots inject people with tiny snippets of the gene for a virus, which the body builds and then uses to learn how to fight the virus. They are faster to design and produce because manufacturers don't have to grow copies of the virus.

The new findings by Moderna do not necessarily mean that mRNA flu shots aren't any better than what we have now. Further, there's still a lot more data to collect on the efficacy of these vaccines. Moderna is preparing to conduct larger trials that would test how well the shots actually keep people from getting sick in the real world (not just testing antibody levels), the report said.

Participants in the Moderna study who received the 50 Aug dose, including older adults, achieved robust increases in geometric mean antibody titers against H1N1 and H3N2, the strains responsible for the vast majority of morbidity and mortality in this age group.

Seasonal flu (influenza A and influenza B) epidemics occur seasonally and vary in severity each year, causing respiratory illnesses and placing substantial burden on healthcare systems. The WHO estimates approximately 3-5 million severe cases of flu occur each year globally with 290,000-650,000 flu-related deaths annually.

"Even before the Covid-19 pandemic, approximately three million people died each year due to respiratory infections, and many more are hospitalised or become ill as a result of these viruses," said Stephane Bancel, Chief Executive Officer of Moderna, in a statement.

"We believe our mRNA platform is well-positioned to address the significant unmet need in seasonal flu," Bancel added.