Pfizer and BioNTech’s combination flu and COVID-19 vaccine resulted in a robust immune response in a Phase 1/2 study, the companies announced Thursday.

The release of the topline data trailed just a few weeks behind Moderna, which announced at the beginning of the month that its own combo flu and COVID-19 vaccine was effective in a Phase 1/2 trial.

The drugmakers are now competing to get their respective combo vaccines to the finish line, as they expect a continued drop in COVID-19 product sales as well as single-strain vaccinations.

The Pfizer and BioNTech trial tested the mRNA combo vaccine in adults aged 18 to 64 and compared it to a currently licensed flu vaccine — as well as to the companies’ updated bivalent COVID-19 shot designed for the Omicron BA.4/BA.5 strain.

The results showed the combo vaccine boosted protection against influenza A, influenza B and SARS-CoV-2.

“We are encouraged by these early results in our Phase 1/2 study,” said Annaliesa Anderson, SVP and head of vaccine research and development at Pfizer, in a statement. “This vaccine has the potential to lessen the impact of two respiratory diseases with a single injection and may simplify immunization practices for providers, patients and healthcare systems all over the world.”

Anderson added that mRNA vaccines reliably induce robust antibody and T-cell responses and that the company is looking forward to launching a Phase 3 trial.

The latest data is another step in Pfizer’s long-term goal of developing a pipeline of combination respiratory vaccines, as its COVID-19 portfolio is expected to continue deflating in sales. 

This month, the pharma lowered its full-year guidance for its COVID-19 vaccine Comirnity’s revenues by $2 billion and announced an expected drop of $7 billion for its oral COVID-19 treatment, Paxlovid.

Drugmakers are hoping that combo vaccines may make it easier and more convenient for people to get an all-in-one shot to help reverse the downward trend of both COVID-19 and flu vaccinations.

“Studies of confirmed viral infections suggest that COVID-19 adopts a seasonal pattern with peaks in fall and winter, similar to other respiratory diseases,” said Ugur Sahin, CEO and co-founder of BioNTech, in a statement. “Co-infections as well as consecutive respiratory infection during this period can further increase the risk of severe illness. Combination vaccines have the potential to become a mainstay of routine vaccination against respiratory diseases, especially for the vaccination of populations who have a higher risk of severe illness.”