Building on the success of their Covid-19 vaccine, the US pharmaceutical company Pfizer started a clinical trial to test an influenza vaccine using mRNA technology. The goal is to improve the currently used flu vaccines, which only have an efficacy of 40% to 60% against a disease that can cause up to 650,000 deaths per year.

Pfizer dosed the first participants in a study to test the vaccine it developed with the German company BioNTech, the same one it worked with for its Covid-19 vaccine. The study, an early-stage Phase 1 clinical trial, will look at the safety, tolerability, and immunogenicity responses compared to another flu vaccine approved by the FDA. 

About 650 healthy adults aged 65 to 85 will be recruited in the US to participate in the study by Pfizer. The candidates will encode WHO recommended strains, which will be followed later by multivalent combinations. As the program progresses, strains could be updated based on recommendations for subsequent influenza seasons, Pfizer said.

Kathrin U. Jansen, Head of Vaccine Research and Development at Pfizer, said in a press statement that the company has been working since 2018 on a potential MRNA influenza vaccine. The pandemic provided an “immense scientific opportunity” for mRNA, especially considering the improved efficacy needed with flu shots, she added.

Moderna, the pharmaceutical company that also developed an mRNA vaccine for Covid-19, had already announced in July the start of an early-phase clinical trial. Back then, the US company had said that if the trials are successful, they will seek to bundle the vaccine with three other mRNA-based ones so as to have a yearly one-stop shot. 

The role of mRNA vaccines

Before the Covid-19 pandemic, mRNA vaccines were largely experimental — many researchers regarded them as “the next big thing in vaccines,” but they had not yet proven their worth. The impetus brought by the need for new vaccines led Moderna and Pfizer to develop two mRNA-based ones for SARS-CoV-2 in under a year. Now, they want to use this technology for other infectious diseases. 

Receiving an mRNA shot means being injected with bits of genetic materials from the target virus instead of the virus itself. Our cells then use that genetic information to learn how to build snippets of the virus that generate an immune response. It’s a highly-anticipated vaccination technology that could help to tackle several diseases. 

The fact that influenza vaccines have to be updated every year to match circulating strains, as well as the expensive and time-consuming production process, make the vaccines ideal candidates for replacement with mRNA technology – which only requires the genetic sequence of the virus and would be produced much faster. 

While not as threatening as Covid-19, the flu is still a big public health problem. It has affected between nine and 45 million people every year since 2010, according to the Center for Disease Control and Prevention. About 650,000 people are killed every year by it, according to the World Health Organization, also causing 5 million cases of severe illness.