Can An Influenza Vaccine Deliver Protection During a Mismatched Flu Season?

FluGen M2SR vaccine is designed to activate wild-type immune response without causing influenza disease
people being protected from rain with an umbrella
(Precision Vaccinations)

FluGen, Inc. announced in a press release that it has completed dosing in a first-of-its-kind clinical study which challenged subjects with an influenza virus that was intentionally mismatched by 6 years from the influenza strain utilized in its novel intranasal M2SR vaccine. 

“This is a bold study which, if successful, would significantly advance our progress towards developing a flu vaccine which could provide broader protection against influenza,” said Dr. Robert Belshe, chair of the FluGen, Inc., clinical advisory board and the Diana and J. Joseph Adorjan Endowed Professor of Infectious Diseases and Immunology, Emeritus, at Saint Louis University. 

“Imagine if a vaccine could protect people from the flu, even when such a mismatch occurs. The implications for the improvement of influenza vaccine efficacy are significant.”   

“Since 2004, there have been at least 5 influenza seasons where the recommended influenza vaccine has not matched 1 of the common circulating strains in the U.S., which has resulted in lower vaccine efficacy,” said Dr. Belshe. 

Despite the annual update, the annual vaccine effectiveness has varied from 10 to 60 percent over the last 10 years in the USA, says the Centers for Disease Control and Prevention (CDC). 

In the study, more than 100 subjects were randomized 1:1 to receive either an intranasal placebo or a single intranasal dose of the M2SR vaccine, manufactured with the A/Brisbane/10/2007, H3N2 strain of influenza, which was utilized in marketed influenza vaccines during the 2008-2010 influenza seasons. 

Subjects were then challenged intranasally with the A/Belgium/4217/2015, H3N2 influenza virus, which is a genetically drifted virus that caused outbreaks of influenza in 2015. 

Study subjects are being followed on an ongoing basis for 4 months. 

The FluGen vaccine utilizes a proprietary M2 deleted, single replication (M2SR) influenza virus. The M2 gene is essential for the influenza virus to spread in the patient and the deletion of the M2 gene restricts the virus to a single replication cycle in the host. 

The body recognizes M2SR as an influenza infection and activates its robust immune response, but, because the virus can only replicate once, it cannot spread to other cells and cause symptoms of a real-world infection. 

Patients naturally infected with wild-type influenza often are protected from future influenza illness for many years. 

By convincing the body it has been infected with influenza, the M2SR vaccine is designed to activate this broad and durable wild-type immune response, without causing influenza disease. 

This study is supported by a $14.4 million grant from the Department of Defense under Award No. W81XWH-17-1-0430. 

A prior Phase 1a study of FluGen’s M2SR vaccine in 96 subjects showed the vaccine to be generally safe and well tolerated, and to generate a robust immune response. 

FluGen, Inc. is a clinical stage vaccine company focused on improving the breadth and effectiveness of influenza vaccines. For more information about FluGen, Inc., please visit