Study to Evaluate Experimental Adjuvants for Seasonal Influenza Vaccine

The National Institutes of Health (NIH) has announced the launch of an early-stage clinical trial to evaluate the safety and efficacy of 2 licensed seasonal influenza vaccines, administered with or without novel adjuvants.

Although seasonal influenza vaccines have been available for decades, effectiveness varies depending on how well the vaccine matches the seasonal strain circulating in a given year. When an adjuvant is added to a vaccine, individuals are more likely to produce a stronger immune response, which may provide better protection.

The phase 1 trial will enroll 240 healthy adults between 18 to 45 years at 8 Vaccine and Treatment Evaluation Units, which comprise a network of clinical trial sites funded by the NIH’s National Institute of Allergy and Infectious Diseases. The trial is expected to last approximately 18 months.

For the study, participants will be randomized to receive 1 dose of the northern hemisphere 2018-2019 influenza seasonal version of either Fluzone quadrivalent influenza vaccine or Flublok quadrivalent influenza vaccine, which will be administered alone or in combination with either the AF03 or the Advax-CpG55.2 adjuvant.

After receiving the vaccine, enrolled participants will be monitored by study investigators and will be required to return to the clinic for regular visits for at least 57 days. During this time the investigators will monitor for adverse effects and collect blood samples to track vaccine-related immune responses.

Ninety days after vaccination, all volunteers will receive a dose of a 2019-2020 seasonal quadrivalent influenza vaccine without adjuvant and will be observed for adverse effects. The participants who received Fluzone initially will receive the updated Fluzone vaccine and volunteers who received Flublok will receive the updated Flublok vaccine.

At the participants’ final clinical visit, which will take place a year after their first vaccination, the investigators will conduct a final blood draw and will ask for a total account of any adverse effects.

Both Fluzone and Flublok are manufactured by Sanofi Pasteur and are reformulated each year. Fluzone is made from inactivated influenza viruses grown in chicken eggs and Flublok is an egg-free recombinant vaccine made up of a surface protein of influenza virus, hemagglutinin, which is engineered to achieve an exact genetic match to the World Health Organization-selected influenza strains each year.

The 2 novel adjuvants that are being tested in the study have demonstrated promise in enhancing the immune response to influenza vaccines in animal models. Both adjuvants were also shown to be well-tolerated when given in conjunction with either Flublok or Fluzone in additional animal models.

According to the statement issued by the NIH, 1 of the adjuvants, AF03, which is developed by Sanofi Pasteur, has also been shown to improve human immune responses to avian influenza vaccine.

The other adjuvant, Advax-CpG55.2, which is developed by Australian company Vaxine Pty Ltd, is the most recent formulation of a sugar-based adjuvant that has been shown to increase vaccine-related immune response elicited for influenza in humans.

Investigators are hopeful that the completed study will provide more information on the safety and immunogenicity of adjuvanted seasonal influenza vaccines. Specifically, the research team hopes that the study will determine the best combination of vaccine and adjuvant needed to provide robust immunity, which will improve the protection afforded by seasonal influenza vaccination.