My Mother-In-Law boarded the Ryndam Sunday in Tampa after it has suffered two previous cruises with a Norovirus outbreak. The ship is following anti epidemic procedures including a complete cleaning before new passengers can board, no salt and pepper shakers, and no self serve in the buffet area. I gave her the standard advice about vehemently washing her hand after she has touched any surface and before she touches food, utilizing the hand santizers provided by the ship whenever she passes by, and using a cloth or a towel to open the door when exiting the restroom. However, if the new Norovirus vaccine continues to show promise, ship wide epidemics could soon be a worry of the past.
The CDC provides us with the following facts about the illness:
The study sponsor, LigoCyte, provides us with the following statistics:
“Viral Gastroenteritis > Norovirus > Illness Key FactsNorovirus—the stomach bug Norovirus is a highly contagious illness caused by infection with a virus called norovirus. It is often called by other names, such as viral gastroenteritis, stomach flu, and food poisoning.
Norovirus infection causes acute gastroenteritis (inflammation of the stomach and intestines); the most common symptoms are diarrhea, vomiting, and stomach pain.
Anyone can get norovirus, and they can have the illness multiple times during their lifetime.
Norovirus is the most common cause of acute gastroenteritis in the United States. Norovirus illness can be serious Norovirus can make people feel extremely ill and vomit or have diarrhea many times a day.
Most people get better within 1 to 2 days.
Dehydration can be a problem among some people with norovirus infection, especially the very young, the elderly, and people with other illnesses.”
“The Centers for Disease Control and Prevention (CDC) had been particularly active in improving the estimates of norovirus disease
burden. Their recent findings highlight the advances in norovirus epidemiology and suggest that the burden is similar to other
infectious diseases where immunization has become standard practice:
• Norovirus afflicts 21 million people per year in the U.S.
• The community attack rate of norovirus in the U.S. is 6.5%.
• Norovirus is responsible for 200,000 deaths annually in children • From 1999-2007 norovirus caused, on average, 797 deaths per year in the U.S., surging up to 50% during epidemic seasons.
• Norovirus is the leading cause of acute gastroenteritis in the community, and among persons seeking care in outpatient clinics or
• Norovirus leads to an estimated annual mean of 71,000 hospitalizations in the U.S., surging to 100,000 during epidemic seasons.
– 18,500 to 37,000 hospitalizations per year are in children $10B in indirect loses and costs.
• Norovirus accounts for over 5 million cases (58%) of food poisoning annually, resulting in 14,600 hospitalizations.”
Promising, but not 100% effective
The company has developed two promising forms of the the vaccine, an injection form and a nasal spray. Both contain no active virus, but instead virus like particles. In testing they gave the vaccine to 47 test participants and placebo to 43 participants. They then exposed the participants orally to about 10 times the amount of the virus needed to typically infect about half of the general population. The results of the testing showed that the new vaccine is about 50% in preventing the disease and reduced the severity of the disease of those who still came down with it by 35%. Generally, most vaccine producers try to achieve an 80% to 90% effectiveness rate. However, the vaccines still needs to be tested in the “wild” as sometimes the effectiveness rate improves when subjects are casually exposed to an infectious agent rather than an intentional clinical exposure. The immunity to the virus can last about 2 years as this is an agent that tends to mutate through genetic drift like influenza. Hence, like the influenza vaccine, the Norovirus vaccine would need to be updated and re-administered every year or two.
LigoCyte may choose to still make the vaccine available even at the only 50% effectiveness rate as it still could benefit those in institutional settings and the elderly who are extremely vulnerable to the virus. Cruise ships may be one of those “institutional settings” where the general population as well as the crew could benefit from the vaccine even with an only 50% effectiveness rate.