'Broad-based' flu vaccine could provide basis for lifelong immunisations

New jab primes the immune system against parts of the virus which are common in multiple different flu strains

NHS staff have been urged to get the flu jab this year in anticipation of a particularly bad winter (PA)

A broad-spectrum vaccine that has been successful in providing immunity to four major flu strains could pave the way for “complete and lifelong protection” against influenza, researchers have said.

The new vaccine was significantly more effective, when tested on mice, than the conventional jab used in seasonal vaccination drives which typically targets one major strain.

Vaccination programmes in the run up to winter are targeted to the strains of flu that are most likely to cause serious outbreaks that year.

But influenza viruses are constantly evolving, and this means that some years the vaccines may be less effective or a flu strain might be especially harmful to certain groups.

NHS England chief executive Simon Stevens has said the health service is braced for a “heavy flu season” after hospitals in New Zealand and Australia struggled to cope during their winter.

Australia experienced its worst flu outbreak for 20 years with 70,000 cases reported, and NHS chiefs fear a similar result if this year’s jab is ineffective in the elderly.

So a long-lasting, broad-acting flu vaccine is a major target for infectious disease research.

The study from researchers at the Nebraska Centre for Virology and published this month in the journal, Scientific Reports, targeted its vaccine on genes which are found in four major flu strains.

The genetic targets are likely to be preserved even as the viruses adapt and are common to H1, H2, H3, H5 flu strains. The virus families have caused global flu outbreaks in recent years, including “bird flu” (H5N1) and “swine flu” (H1N1) and the jab primes the immune system to look for traits which are common across all the strains.

The researchers injected vaccinated mice with lethal doses – “enough influenza to kill 50 mice” – from nine flu viruses across these four groups.

It found that once vaccinated, the mice would survive a lethal flu exposure eight times out of nine. And this broad resistance was only slightly worsened at a lower dose of the vaccine.

The mice did still get ill but the effects were greatly reduced. The paper says mice survived a dose that should have been lethal 100 per cent of the time, but it adds: “These mice do show signs of disease and weight loss, but fully recover from the infection.”

This was compared to two vaccines used for seasonal immunisations in America that were effective in the flu strains they were designed to protect against, however none were able to protect mice against a lethal dose of a different strain.

“Clearly, the protection at these extremes demonstrates that this vaccine could be very effective,” if this were a natural influenza pandemic, the paper concludes.

“It is very possible that a vaccine similar to the one described in this study could provide complete and lifelong protection against all known human influenza variants.”