A potentially groundbreaking seasonal flu vaccine developed by a team from Oxford University will be tested on around 2,000 humans aged 65 and above living in Berkshire and Oxfordshire in the United Kingdom. The clinical trial, supported by the UK’s National Institute for Health Research, will be carried out through Britain’s publicly funded national healthcare system, the National Health Service (NHS). Why is this trial significant — to the world and to India?
What kinds of influenza will the new vaccine target?
Influenza or flu is a viral seasonal respiratory disease to which older people and young children are the most vulnerable. Influenza viruses are classified into A, B, C and D types — A and B are known to cause seasonal epidemics; C causes mild respiratory illness, but not an epidemic. Influenza D affects cattle. Influenza viruses annually affect about a billion people worldwide, and cause 250,000 to 500,000 deaths, mainly in the over-65 age group. The new vaccine has been developed by Oxford University’s Jenner Institute with Vaccitech, its spin-out biotech company. According to Oxford University, the new vaccine will target influenza viruses A, B and C.
How long has the project been ongoing?
Professor Sarah Gilbert, professor of vaccinology at the university and co-founder of Vaccitech, and her collaborators at the Jenner Institute have put in 10 years of work into the vaccine. Vaccitech officials say they have also conducted five studies with over 150 subjects, all published in peer-reviewed journals. A small lead-in safety study has been conducted in a small number of patients with this most recently manufactured lot of the vaccine.
Why is the new vaccine significant?
The researchers believe that the “different mechanism” of the new vaccine will provide stronger protection against the flu, and could reduce its severity and duration. “We are hoping to reduce the burden of influenza disease… which would result in fewer clinic visits, hospitalisations and deaths, if the vaccine works as predicted. We would try and use this vaccine throughout all areas in which influenza vaccination is not widely available, due to the lack of present perceived benefit,” Vaccitech Chief Executive Tom Evans told The Indian Express in a email interview. The developers feel the vaccine could be a game changer for global health.
And what exactly is this “different mechanism”?
Under a microscope, the flu virus looks like a spherical pin cushion with lots of pins sticking out of it. Available vaccines use surface proteins that lie on the outside of flu cells — the heads of the pins — to stimulate the immune system, which ultimately produce antibodies. But every year, as the virus changes, the surface proteins (hemagglutinin and neuraminidase) also change. Currently, every year, scientists are going back to the drawing board to predict how the virus might change, and what the new strain of flu might look like. Often, the vaccine doesn’t work well because “by the time the vaccine has been made, the strain of virus that is causing the illness has changed”, say experts.
The new universal vaccine uses core proteins of the virus — lying inside the cushion — rather than the ones on the surface. “Our vaccine targets conserved areas of the virus, and thus does not need to be changed year to year,” Evans said.
The new vaccine will stimulate the immune system to boost influenza-specific T-cells (the body’s own immunity-building cells), instead of antibodies, that kill the virus as it tries to spread through the body. Everyone has some influenza-specific T cells already, but their numbers are often too low to be protective. Previous research found that these T-cells can help fight more than one type of flu virus and this, according to the researchers, means more people could be protected and the severity and duration of flu may be reduced.
Current vaccines are only effective in 30% to 40% of over-65s as the immune system weakens with age. Evans said while the effect of the standard vaccine only lasts 4-6 months, the new vaccine could remain efficacious for a few years.
What is the influenza burden in India. How is the new vaccine expected to help?
The flu burden in India is huge; the total number of cases until October 1 this year had crossed 36,000 countrywide, and the number of deaths was close to 2,000. “If it (the vaccine) passes all tests of safety and immunogenicity, it will be a breakthrough, and will further help all countries struggling to tackle the worldwide problem of influenza,” Dr A K Tahlan, director, Central Research Institute, Kasauli, said. CRI is one of the National Influenza Centres of WHO in the country.