Flu comes back every year because when you catch it or are vaccinated, your immune system is only trained to identify the flu's large surface proteins. Every year, between 250,000 and 500,000 people of all ages die worldwide after getting seasonal flu, partly because few people are vaccinated for it.
Earlier this year, Sarah Gilbert and colleagues at the University of Oxford equipped the virus used in the smallpox vaccine, which stimulates cell-mediated immunity, with two proteins common to all flu viruses. They reported that this vaccine prevented symptoms in some people experimentally infected with flu, and those that did get sick had milder symptoms.
Now Colin Butter and colleagues at the Institute for Animal Health in Compton, UK, have tested that vaccine, and a similar one made of a different live virus, in chickens. Just as in people, it did not prevent infection, but the birds' T-cells responded strongly, and less of the virus was passed on.
Gilbert reports that her team has tested such a combination in people, and has seen cell-mediated immunity to the universal proteins, as well as antibodies to specific surface proteins.