February 27, 2023 — Renowned experts discussed the immunologic and serologic issues related to dengue vaccination, the latest findings of the Institute for Child Health and Human Development’s (ICHHD) ongoing dengue studies, and the updates on the country’s dengue control programs amid the COVID-19 pandemic during a forum held on January 18 at the Rizal Park Hotel.
“Together, we are working to provide more insights on dengue immune response which may help in the development of a better dengue vaccine,” said Dr. Jacqueline Deen, ICHHD adjunct research professor and principal investigator of the dengue studies.
Each of the four distinct dengue virus stereotypes is capable of causing the full spectrum of dengue illness, according to Dr. Anna Durbin, professor of International Health and director of the Center for Immunization Research at the Johns Hopkins Bloomberg School of Public Health. However, while each stereotype offers long-term homotypic immunity against that specific serotype, it only offers short-term heterotypic immunity. A secondary infection with a different serotype is highly related to severe disease.
Dr. Leah C. Katzelnick from the US National Institutes of Health stated that the mechanism for this severe disease is called “antibody enhancement” where antibodies induced from that first infecting virus are able to bind but not neutralize the new infecting serotype. This enables the virus to easily get into the cells leading to increased viremia and change the immune response to infection, ultimately causing a more severe disease.
Unfortunately, Dengvaxia does increase the risk of severe disease in individuals who have never had dengue before because the vaccine acts like a primary dengue infection. However, individuals who have had dengue or are still positive for the disease will be significantly protected against more severe disease if given the vaccine.
According to Dr. Michelle Ylade‘s research, vaccination provides protection against more serious dengue illness. She maintained that vaccination should still include a pre-vaccination screening so that only those who are seropositives are given the vaccine.
“What we have learned is that under some conditions, strain variation between dengue genotypes within a serotype can lead to immune escape and vaccine failure,” said Dr. Aravinda de Silva, professor at the University of North Carolina at Chapel Hill.
All four strains of dengue are now circulating in the Philippines where the disease is hyperendemic. These are crucial factors to take into account when developing a dengue vaccine.
Charmaine Lingdas | Published in UP Manila Healthscape No. 48 (February 2023)
