A newly developed vaccine could help put an end to the painful, debilitating dengue fever that sweeps through the Virgin Islands in outbreaks every few years, but there are fears as well as hope. The concern is that it would provide only limited relief and that distribution would require onerous precautions to avoid the possibility of putting some people at risk for more serious symptoms.
Last week the U.S. Food and Drug Administration announced it has approved the vaccine Dengvaxia, but with restrictions. It may be given only to individuals aged 9 to 16 who have already had a verified case of dengue. This is the first ever FDA approved dengue vaccine.
Initial excitement about the breakthrough was soon dampened as national news outlets brought attention to a controversy in the Philippines, where hundreds of parents contend their children became seriously ill after participating in a Dengvaxia vaccination campaign in 2016.
That was before use was restricted to people who had previously had dengue.
Contacted for comment Monday, territorial epidemiologist Dr. Esther Ellis said, “We’re working to determine the appropriateness” of the vaccine for the Virgin Islands.
Late Monday the Health Department issued a press release quoting acting Commissioner Justa Encarnacion, saying Health officials are “excited” about the vaccine but adding “we are working diligently within the Department of Health to understand how the vaccine could work for us with its current conditions.”
The release promised to “share information as soon as it is available.”
Ellis said Puerto Rico is also making its own assessment about whether to use the vaccine.
Dengue is endemic in both Caribbean U.S. territories as well as in American Samoa and Guam, the FDA announcement said. It is also endemic in many non-U.S. regions throughout the tropics. It is not generally found on the U.S. mainland. The Centers for Disease Control and Prevention estimates that annually 400 million people are infected with the virus, resulting in about 20,000 deaths.
The last outbreak in the Virgin Islands was in 2012, Ellis said. Since the virus becomes active in a community in cycles of about five years, that means the territory is due for another outbreak.
There are four strains of the disease. Ellis said serotype one and serotype two have both been found in the Virgin Islands. Serotype three and four have not.
Dengvaxia is FDA-approved to prevent all four types. The FDA describes it as “a live, attenuated vaccine that is administered as three separate injections, with the initial dose followed by two additional shots given six and 12 months later.”
The dengue virus is spread from person to person through the bite of the Aedes Aegypti mosquito. Symptoms include headache, rash, fatigue and joint pain. Especially in first cases, symptoms may be mild and be easily confused with the flu.
A subsequent infection can lead to a more severe form of the disease, including dengue hemorrhagic fever, and can be fatal, according to the FDA release. Symptoms include persistent vomiting, bleeding and confusion and difficulty breathing.
“Because there are no specific drugs approved for the treatment of dengue disease, care is limited to the management of symptoms,” it states.
According to the FDA release, the vaccine also has been approved in 19 countries and in the European Union.
The World Health Organization first recommended Dengvaxia for all children ages 9 to 16, in July 2016, but later limited the recommendation only to those who had had a verified case of dengue.
A story published last week by National Public Radio explained the reason for the restriction. As with other viruses, a person who has been infected develops antibodies. But dengue is “tricky.” On a second attack, instead of being repulsed by the antibodies, it uses them to spread throughout the body. Thus the disease becomes worse on subsequent infections. In the case of the children in the Philippines, the vaccine may have acted as a first case, thus setting them up for a more severe infection when they encountered the virus again.
Dengvaxia is produced by a French pharmaceutical company, Sanofi Pasteur, which spent 20 years and $2 billion in its development, according to the NPR story. The company conducted several trials with more than 30,000 children globally.
Problems with the roll-out in the Philippines are blamed for a dramatic drop in that nation’s confidence in immunization in general, according to the NPR story. It cites a recent study showing that 82 percent of parents had confidence in vaccines in 2015, but that number declined to just 21 percent in 2018.