What Will It Take to Develop a Universal Flu Shot?

This year’s flu season has arrived, bringing with it more news of early cases around the country, as scientists and health experts consider what it will take to develop a universal influenza vaccine.

The Centers for Disease Control and Prevention’s (CDC) weekly influenza surveillance report, FluView, details flu activity throughout the year. The recent report for week 40, ending October 7, marks the first report of the 2017-2018 flu season and includes data on viral surveillance, mortality, hospitalizations, outpatient illness surveillance, and geographic spread of influenza. According to the new report, during week 40, Colorado and South Carolina reported local flu activity, while 38 states and the District of Columbia reported sporadic flu activity; 10 states reported no flu activity. In an early reminder on the risk of the flu, California’s Yolo County reported its first flu death of the season, that of a middle-aged man who had significant pre-existing medical conditions.

“Vaccination is the best method to protect oneself, reducing the chance the person who receives the flu shot will become ill, and reducing the spread of flu in family, friends and the community,” said county health officer Ron Chapman, MD, MPH, in a statement.

With health experts urging everyone to receive a flu shot, a new article published in the journal Immunity reports on a workshop recently held by the National Institute of Allergy and Infectious Diseases (NIAID) on the development of a universal influenza vaccine. An advisory group of health experts from around the world meets twice each year to review surveillance data on antigenic changes in circulating influenza viruses, using that data to make recommendations on components for the upcoming seasonal flu shot. Annual flu shots are the best way to protect against changes in circulating viruses that occur from season to season, though, at best, the influenza vaccine is only 40% to 60% effective at preventing illness when well-matched to viruses in circulation.

“Historically, we don’t do very well with influenza even when we have a good match with the vaccine,” said the report’s co-author, NIAID Director Anthony S. Fauci, MD, in an interview with Contagion^®, noting the difficulty in preparing for seasonal minor drifts, pre-pandemics, such as H5N1 and H7N9 influenza viruses, and the unexpected pandemics that occur with abrupt virus changes. However, Dr. Facui noted that we may be just several years away from having a flu vaccine that covers most of the influenza A viruses in group 1, including H1 and H3 viruses. “A universal vaccine would protect against even the dramatic changes that occur when a pandemic evolves.”

At the recent NIAID meeting, attendees discussed the goals of developing a vaccine to cover all or most seasonal strains of influenza A and influenza B with improved efficacy, as well as improved breadth and duration of protection. While such a shot with 90% efficacy would be ideal, say the paper’s authors, meeting attendees noted that a vaccine offering 75% efficacy would be a feasible target. The workshop focused on the research and new technologies needed to create a universal vaccine, such as the development of new antigens capable of eliciting broader antibody responses and finding ways to target parts of the influenza virus that stay mostly unchanged from season to season.

Two key themes emerged in the workshop. The first was the need for more population-based data from natural history studies in prospective cohorts to provide the longitudinal data and samples needed to better understand properties of the influenza virus, as well as the immune response to infection and vaccination. “Second, the human challenge model also will be a crucial tool for vaccine development, as it can help answer fundamental questions about influenza immunity and serve as a mechanism for rapidly testing the efficacy of new products,” the paper’s authors write. “The human challenge model is a unique resource as it provides the ability to study the host, the virus, and the timing of influenza exposure, which is difficult to recapitulate in nature.