"Winter vomiting" vaccine just a sniff away Published on Saturday 18 February 2012 01:39 A VACCINE against the norovirus - or "winter vomiting bug" - could be available within five years, scientists believe. Two rival groups in the US are working on vaccines that are close to being tested in clinical trials. However, they would not be injected into the bloodstream but sprayed or puffed into the nose as a liquid or powder. Inside the nostrils they would trigger an immune response that is repeated when a norovirus enters the stomach. Noroviruses produce non-fatal but unpleasant bouts of illness leading to violent repeated vomiting and diarrhoea. The viral particles can be carried in the air or on tiny amounts of contaminated food and are highly contagious. The problem has hit Scottish hospitals over successive winters - in November last year an outbreak of norovirus affected 70 patients and 22 staff in seven wards at Monklands Hospital in Airdrie, resulting in the cancellation of dozens of operations - but can affect anywhere with communal facilities. Professor Charles Arntzen from Arizona State University, who leads the team developing the "powder puff" vaccine, said: "We're coming up with a vaccine which will be in a little spray device. It's single use, you get a puff of powder. And our current formulation is showing a wonderful immune response. The technical issues are being solved. Now it's a regulatory issue. If everything went well and if there was enough financial support I could see us having a vaccine in four to five years. He predicted the cost to be about £25-£31 per dose. To stay protected, treatment might have to be repeated at intervals of between six months to two years. Meanwhile, a team at the company LigoCyte is researching a similar nasal vaccine in a liquid spray. Both vaccines are made from empty shells of norovirus particles minus their genetic material. These are harmless, but the protein shells can be recognised by the immune system, which remembers how to identify them. Next time a real norovirus invades the body, the immune system swings into action. LigoCyte's vaccine is produced in insects while Prof Arntzen's version is manufactured in tobacco plants. "You get leaves of the tobacco plant chuck full of viral particles," said the professor, speaking at the annual meeting of the American Association for the Advancement of Science in Vancouver, Canada. A kilogram of leaf material will make 10,000 doses of the vaccine. We can produce ten million doses of vaccine in two weeks. It's ready to go from a commercial perspective. To manufacture the vaccine, a tobacco mosaic virus is genetically altered so that it constructs the outer shell of a norovirus. The powder is designed to stick in the nose for around three hours, enough time for an immune reaction to occur. However, the vaccine is currently only 50 per cent effective - for a vaccine to have a meaningful impact on the spread of infection, it has to protect 80 per cent of a population. Prof Arntzen added: "It's a tough little virus. Once it gets into the environment its hard to get rid of. It takes as little as ten viral particles on a door knob to cause an infection. Recovery may be quick, but a person who has had norovirus will continue to shed viral particles for up to four weeks.