IDWeek 2013: Norovirus Vaccine shows efficacy in early trials

January 12th, 2015

San Francisco: An investigational vaccine was generally well tolerated and effective against norovirus, reducing symptoms of vomiting and diarrhea by 52%, researchers reported last week at IDWeek 2013.¹ Long known as the bane of cruise ships, norovirus can also cause extremely disruptive hospital outbreaks that infect both patients and health care workers and may lead to shutdown of affected units.

In a survey of infection preventionists published last year, norovirus was cited as a leading cause of nosocomial outbreaks.² Currently, there is no treatment for norovirus, the most common cause of severe GI infection in the United States. Norovirus is highly contagious, and some 20 million Americans are infected annually and as many as 800 die. It is estimated that illness and outbreaks of norovirus cost about $5.5 billion annually in the U.S. Norovirus is primarily transmitted via the fecal-oral route, either by direct person-to-person spread or contaminated food or water.

The randomized, multi-center study included 98 people who agreed to drink water containing a significant dose of the virus. Fifty of the participants received the injected vaccine and 48 a placebo injection. Neither the participants nor the researchers knew in advance who received the vaccine. In the vaccine group, 26 (52%) were infected, as were 29 (60%) of those in the non-vaccine group. In people who received the vaccine, 10 (20%) suffered from mild, moderate or severe vomiting and/or diarrhea versus 20 (42%) in the non-vaccine group -- a 52% reduction in symptoms. The vaccine targets two genotypes of norovirus: GI.1 and GII.4, the latter of which is the leading cause of outbreaks in the United States.

“If the vaccine continues to prove as effective as our initial results indicate, it could be used for specific populations or situations – in those at a higher risk of severe disease such as the elderly or at high risk for infection or transmission such as in day care, people going on a cruise, those in nursing homes or in the military,” said David Bernstein, MD, MA, professor of pediatrics at Cincinnati Children’s Hospital Medical Center and the University of Cincinnati and lead author of the study. “Or it could be offered to everyone, since all of us are exposed at one time or another.”

References

1. Bernstein DI, Atmar RL, Lyon M, et al. An Intramuscular (IM) Bivalent Norovirus GI.1/GII.4 Virus Like Particle (VLP) Vaccine Protects Against Vomiting and Diarrhea in an Experimental Human GII.4 Oral Challenge Study. Abstract LB-2. IDWeek 2013, San Francisco, Oct. 2-6, 2013.
2. Rhinehart E, Walker S, Murphy D, et al. Frequency of outbreak investigations in US hospitals: Results of a national survey of infection preventionists. AJIC 2012; 40:2-8.