While H7N9 avian influenza does not seem to move easily from person to person, the WHO notes that most people who catch it become severely ill. Several candidates for H7N9 pandemic flu have proven safe and immunogenic in clinical trials, but experts recommend that these be beefed up for practical use either via multiple doses or using an adjuvant. The National Institute of Allergy and Infectious Diseases (NIAID) reported on Thursday that a team of scientists has successfully tested a prime-boost vaccine for the flu strain in a small clinical trial.
The team used a live vaccine manufactured by AstraZeneca's ($AZN) MedImmune as the "primer" dose and an inactivated virus vaccine made by Sanofi ($SNY) as the "booster" dose. The live vaccine, which contains a weakened form of the virus, introduces the immune system to H7N9, the NIAID said in a statement. And the "booster" dose, containing inactivated virus, provokes a more robust immune response.
The trial involved 65 volunteers, 48 of whom were aged 18 to 49 and 17 of whom were aged 50 to 70. The latter group is an important demographic, as its members are most susceptible to severe disease from H7N9 flu, the NIAID said.
Participants received either one or two doses of the "primer" vaccine, followed by one dose of the "booster" vaccine 12 weeks later. Both jabs were well tolerated. And while the live vaccine generated a long-lasting immunity that was quickly recalled by a dose of the "booster" shot, scientists are still uncertain if the live vaccine alone is enough to provide protection against H7N9 infection.
H7N9 influenza has infected 681 people and killed at least 275 since first surfacing in China in 2013. It has not been found in the U.S. The prime-boost approach has been used in Ebola vaccine regimens, with GlaxoSmithKline ($GSK) teaming up with Emergent BioSolutions ($EBS) and Johnson & Johnson ($JNJ) combining its jab with Bavarian Nordic's. Johnson & Johnson has also tested a prime-boost HIV jab in nonhuman primates.
- read the release