Flu News Day, 10/12/2022

Since news broke regarding the initial success of Moderna’s mRNA flu vaccine phase 3 trial, Pfizer has now begun a phase 3 clinical trial of its mRNA-based influenza vaccine. The trial will include 25,000-subjects based in the United States. Moderna’s trial included 6,000 participants from countries in the Southern Hemisphere and plans on running a larger study in countries in the northern hemisphere during the 2022-21 flu season. Both trials aim to show safety, efficacy, tolerability, and immunogenicity of the vaccine. The success of these trials could result in a more efficacious vaccine, decreasing the annual influenza burden including hospitalization and death. Moderna has previously had positive results with mRNA flu vaccines. In 2019, early data from its phase 1 trials showed efficacy against H10N8 and H7N9 influenza viruses. The latest attempt by both Pfizer and Moderna is to target multiple strains, including influenza A H1N1, H3N2 and influenza B Yamagata and Victoria. Read more about Pfizer’s trial here.

The classification of influenza virus strains based on hemisphere region has been a point of contention among researchers and public health experts. Influenza vaccine supply in the northern- and southern-hemispherical region is based on WHO’s recommendations that predict the most likely circulating influenza virus strains for the upcoming seasons; data they acquire using their Global Influenza Surveillance and Response System (GISRS). The classification based on geographical equator does not account for changes in patterns of influenza circulation within a subregion. For example, in India the northern-hemispherical pattern of circulation is observed in the state of Kashmir while a southern-hemispherical pattern of circulation is observed in New Delhi, a city just under 500 miles apart from Kashmir. Countries near the geographical equator are also known to have year-round circulation of influenza. You can read more about the classification of influenza strains based on region here.

A recent study found a combination vaccine candidate against both SARS-CoV-2 and H1N1 influenza to be effective in mice models. To date, there exists no effective vaccine that could simultaneously mitigate both SARS-CoV-2 and influenza A infections. Morbidity and mortality among elderly and obese people due to simultaneous infection of both SARS-CoV-2 and influenza A, along with a growing consensus on the regular need for booster shots for COVID-19, highlight the need for a combination vaccine against COVID-19 and influenza. In this study, the combination vaccine candidate elicited protection against both SARS-CoV-2 and H1N1 influenza infections in mice. In this study, the combination vaccine candidate was developed by combining SARS-CoV-2 receptor-binding domain-trimer and influenza H1N1 HA1-trimer antigens and subsequentially measuring immunogenicity. Read more about the study here.

A new study looking to evaluate the severity of influenza illness by vaccination status in multiple countries in South America (Argentina, Brazil, Chile, and Paraguay) found influenza vaccination to offer health benefits to some patients hospitalized with breakthrough influenza virus infections. While many studies have been conducted on benefits of influenza vaccination among populations in high-income countries, this study focused on low- and middle-income countries (LMICs) in South America. The study found that vaccination among participants helped attenuate the severity of influenza illness, shorten length of hospital stay and reduce odds of hospital visits.  Such evidence is critical to justifying the initiation and sustaining of investments by the health authorities in seasonal influenza vaccination, especially in LMICs where multiple health priorities compete for limited funds. Learn more about this surveillance-based cohort study here.