February 22, 2023
Medscape shares data from a study on the risk for illness or death due to influenza for children who receive hematopoietic stem cell transplants (HSCT). The data show a high-dose trivalent influenza vaccine (HD-TIV) offers better protection than standard-dose quadrivalent influenza vaccine (SD-QIV) for this high-risk population. The study was published in The New England Journal of Medicine.
The study – the largest influenza vaccine trial in a stem cell population – was conducted over the flu seasons of 2016-2019. Participants had a median time between transplant and enrollment of 7.8 months. The vaccine doses were spaced to 28-42 days apart and they had hemagglutination-inhibition titers measured to A/H1N1, A/H3N2, B/Victoria and B/Yamagata vaccine-specific influenza antigens.
Injection site reactions and systemic adverse events were assessed for seven days after being administered their doses. Severe reaction frequency was 7.5% for HD-TIV and 6.0% for SD-QIV after one dose, and changed to 7.6% and 6.4%, respectively, after dose two. The noted limitation of the study was that children under the age of three were not included and conclusions were drawn only on 3-17 years of age.
PIDS member Natasha Halasa commented on the study, “The allogeneic stem cell transplant population, especially within the first year posttransplant, is one of the most immune-suppressed populations, therefore placing them at high risk for infectious diseases. Many factors that contribute to the development of infections include underlying disease, donor graft source, and conditioning regimen. Also, these factors make them less likely to respond to standard vaccine doses. And, if they do respond, their response is definitely less robust than that of healthy controls. Our research showed that two doses of HD-TIV is superior to two doses of a SD-QIV for pediatric HCT patients.”