How Many Children in the U.S. Virgin Islands Have Had Dengue? A 2022 School Survey

This page summarizes a CDC and U.S. Virgin Islands Department of Health report on a survey conducted in April–May 2022, under the dengue vaccine recommendations of that time.

In May 2019, the Food and Drug Administration approved Dengvaxia, a live-attenuated tetravalent dengue vaccine made by Sanofi Pasteur. In June 2021, the Advisory Committee on Immunization Practices (ACIP) recommended it for children and adolescents aged 9 to 16 who have laboratory-confirmed evidence of a previous dengue infection and live where dengue is endemic, such as the U.S. Virgin Islands (USVI).

Why screening comes first

Confirming a past infection before vaccination matters for three reasons. Dengvaxia lowers the risk of hospitalization and severe dengue in people who have already been infected, but raises that risk in people who have not. Many dengue infections cause no symptoms. And many people with symptoms never seek care or get tested.

Acceptable evidence is either a past laboratory-confirmed dengue diagnosis or a positive blood test meeting ACIP standards for screening: at least 98% specificity and 75% sensitivity. ACIP also recommends vaccinating where at least 20% of the eligible population has had dengue; at that level, a test meeting those standards has a positive predictive value of at least 90%, minimizing the chance of vaccinating someone who has never been infected.

The survey

The USVI Department of Health asked CDC to help find out how many children in the vaccine-eligible age range had already had dengue. In April–May 2022, students in grades 3 to 7 at 15 schools were invited to take part: 10 schools chosen by random sampling within the territory's two health districts (St. Thomas/St. John and St. Croix) and five chosen by the health department. With parental permission, children were tested with a rapid fingerstick test for dengue antibodies (89.6% sensitivity, 95.7% specificity), and the estimates were weighted to the population and adjusted for the test's accuracy.

Results

Of 372 children and adolescents tested, 152 (41%) were positive, 218 (59%) negative and 2 indeterminate.

• Estimated prior infection was similar in boys and girls.
• It rose with age, from 27% at age 8 to 69% at age 12.
• It was higher in St. Thomas/St. John than in St. Croix.
• Among surveyed children aged 9 to 13, within the vaccine-eligible range, it was 51%.

What it means

Past dengue infection among vaccine-eligible children in the USVI is well above the 20% threshold, so prevaccination screening with a test meeting ACIP's standards would give reliable results. The authors conclude that dengue vaccination with prevaccination screening should be considered as part of a comprehensive dengue control and prevention strategy in the territory, and that other U.S. jurisdictions where dengue is endemic should weigh the risks, benefits and feasibility of adding the vaccine, using serosurveys to guide the decision.

Sources

• Mac VV, Wong JM, Volkman HR, et al. "Notes From the Field: Prevalence of Previous Dengue Virus Infection Among Children and Adolescents — U.S. Virgin Islands, 2022." MMWR 72(11). https://www.cdc.gov/mmwr/volumes/72/wr/mm7211a4.htm
• CDC, dengue areas with risk: https://www.cdc.gov/dengue/areaswithrisk/around-the-world.html