Flu News Day, 10/19/2022

Results from a recent Phase 1 trial of COVID-19-Influenza combination vaccine, which contains Novavax’s COVID-19 vaccine (NVX-CoV2373) and its quadrivalent influenza vaccine candidate, showed positive results. The vaccine candidate was able to generate immune response against SARS-CoV-2 antigens as well as homologous and heterologous influenza strain antigens. No serious adverse effects were reported. 642 adults aged 50 to 70 were enrolled in the trial which tested for safety, tolerability, and immune response. Participants were either vaccinated or previously infected with the SARS-CoV-2 virus. Novavax established a manufacturing partnership with Serum Institute of India, the largest vaccine manufacturer in the world by volume, which will allow for expedited delivery if the vaccine is approved.  This combination vaccine can also utilize the existing supply of cold chain channels for delivery, making it more suitable for distribution in low- and middle-income country settings. Read more about this ‘first of its kind’ trial here.

A new study that examined surveillance data on influenza virus activity across 11 countries predicted a substantial increase in infection burden for the upcoming influenza season 2022-23. The research modelled the impact of public health measures taken to mitigate COVID-19 to assess the effect of those measures on the transmissibility of influenza. The study found a 10-60% increase in the population that would be susceptible to influenza and a 1-to-5-fold rise in magnitude of influenza cases. The model found Singapore and Taiwan to be the most impacted among the countries selected for the study. The study hypothesized an increase in susceptibility to influenza viruses among populations due to the withdrawal of several COVID-19 related social measures. Read the full findings here.

With the CDC and other public health bodies warning against an unprecedented rise in influenza this season, the combination of influenza and COVID-19 together could pose a new public health threat by increasing the rate of people who are hospitalized. Australia has already witnessed three times higher rates of influenza compared to the last 5 years. Doctors warn against the impact of simultaneous infections with many studies finding higher rates of hospitalization and death among those infected with COVID-19 and influenza compared to those who were only infected with one virus. One study found the rate of death to be twice as likely for people infected by influenza and SARS-CoV-2, compared to those who only had COVID-19. Animal studies also found co-infected mice to have lower levels of antibodies against each virus compared to mice that were infected with either influenza or SARS-CoV-2 alone. Read more about studies that investigated co-infection of COVID-19 and influenza here.

Advances in influenza surveillance, enabled primarily by broader use of PCR assays, has allowed for enhanced viral characterization that can lead to better selection of strains for inclusion in seasonal flu vaccines. It is known that seasonal influenza vaccine effectiveness varies greatly from season to season, depending mostly on how closely matched the strains selected for inclusion in the vaccine are to the circulating strains. A recent study, “Influenza During the 2010–2020 Decade in the United States: Seasonal Outbreaks and Vaccine Interventions” examines surveillance data from the US CDC to study influenza trends and the impact of technological advances on improving vaccine effectiveness. Read an interview with one of the study authors here, where you can also find the link to the full article published in Clinical Infectious Diseases.