Boosting the influenza vaccine schedule in children with cancer: a prospective open-label study.

Current immunization guidelines recommend one dose of influenza vaccine for children aged ≥9 years and two doses for younger or vaccine-naïve children. However, children receiving chemotherapy have an attenuated immune response. We performed a prospective open-label study in children undergoing treatment for cancer at Perth Children's Hospital, Western Australia, to examine the safety and efficacy of a boosted influenza schedule. This comprised three vaccine doses for children <9 years of age and two doses for those ≥9 years, with each dose administered at least 4 weeks apart. The additional vaccine dose was well-tolerated with no serious adverse events reported; it also resulted in improved geometric mean antibody titres for A/H1N1 (70 to 97, p = 0.003), A/H3N2 (76 to 104, p = 0.003) and B/Washington (148 to 179, p = 0.03) strains. In summary, a boosted influenza vaccine schedule is safe and improves humoral immune response, providing a readily implementable strategy to protect children undergoing treatment for cancer.