A little more than a year after mapping a path to developing a universal flu vaccine — one of the Holy Grails in medicine — the NIH has a candidate in hand that it’s starting to test in healthy human volunteers.
H1ssF_3928 differs from seasonal influenza vaccines in that it displays a different part of hemagglutinin (HA), one of two proteins that classify flu viruses (the other is neuraminidase, or NA). HA consists of a head and a stem region, and while the head typically receives most of the immune response, it also changes constantly. The new vaccine ditches the head entirely in favor of the stem, which is more constant among different influenza strains.
The HA stem is tagged onto a microscopic nanoparticle made of nonhuman ferritin, a platform that enables scientists to mimic the spiky presentation of HA on a natural influenza virus.
For the Phase I trial, researchers at the National Institute of Allergy and Infectious Disease plan to enroll at least 53 adults, stratified into four different age groups between 18 and 70. They will begin with five members of the youngest cohort, who will receive a single 20-microgram injection, whereas the rest will receive two 60-mcg vaccinations.
The main goal of the study is safety, tolerability and ability to induce an immune response. Results are expected as early as 2020.
A universal flu vaccine can reduce developers’ headache of updating the shots — and the risks of targeting the wrong strains — every year, lowering the chances for a pandemic. When the NIAID unveiled its plan last February, it listed four criteria for a successful candidate:
- Be at least 75% effective
- Protect against group I and II influenza A viruses
- Have durable protection that lasts at least 1 year
- Be suitable for all age groups
Other industry players, including Oxford’s Vaccitech, have also lined up government or non-profit partners to start their own human studies for a clinical effort that still has years to play out.
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