Headlines were made over the weekend after Dr. David Bernstein at the University of Cincinnati and the Takeda Pharmaceutical Company Limited made timely announcements of a norovirus vaccine in development that shows indication of reducing the symptoms of GII.4 norovirus, the most common genotype worldwide. The vaccine is particularly interesting as it does not contain real norovirus but instead uses virus-like particles (VLPs) to mimic GI.1 and GII.4 noroviruses, explained below.
The research group led by Dr. Bernstein conducted a randomized, double-blinded, and placebo-controlled trial of the vaccine, meaning the researchers and the study participants did not know who was getting the vaccine and who was getting the placebo. Healthy adult volunteers were given two injections of the vaccine or placebo 28 days apart, and some were given an infective dose of GII.4 norovirus at least 28 days later.
Out of the 109 people in the study, 56 received the vaccine and 53 received the placebo, and ultimately 50 and 48 people from these respective groups went on to the virus challenge. A little over half of the people in the treatment groups (26 in the vaccine group, 29 in the placebo group) were given an infective dose of norovirus and went into hospital isolation for four days to be monitored for symptoms. The vaccine was well-tolerated by the recipients (headaches and pain at the injection site were the most common complaints) and there was an overall reduction in the severity of norovirus symptoms in people who got the vaccine. Ten people in the vaccinated group had mild, moderate, or severe vomiting and/or diarrhea, compared to twenty in the placebo group, cited as a 52% reduction in clinical signs.
Virus-like particles (VLPs) do not contain the viral genetic material needed to replicate or infect, but their surface closely resembles that of a real virus. The immune system “sees” this masquerading particle and creates antibodies to it, preparing the body for when an actual norovirus comes around. This vaccine has been in the works for some time, since before Takeda, the largest pharmaceutical company in Japan, acquired the Montana-based LigoCyte this time a year ago, with intent to finish clinical trials for LigoCyte’s promising norovirus vaccine and get it into production. Additional research will be needed before you can expect to see the vaccine at your local clinic, but there is more hope for relief in those who experience norovirus firsthand.
Dr. Bernstein’s abstract, presented at IDWeek 2013
Press releases from the Takeda Pharmaceutical Company Limited: