Immunogenicity of the inactivated influenza vaccine in children who have undergone allogeneic haematopoietic stem cell transplant

Abstract

Influenza vaccination is recommended for children following allogeneic haematopoietic stem cell transplant (HSCT), however there is limited evidence regarding its benefit. A prospective multicentre study was conducted to evaluate the immunogenicity of the inactivated influenza vaccine in children who have undergone HSCT compared with healthy agematched controls. Participants were vaccinated between 2013 and 2016 according to Australian guidelines. Influenzaspecific hemagglutinin inhibition antibody titres were performed prior to each vaccination and 4 weeks following the final vaccination. A nasopharyngeal aspirate for influenza was performed on participants that developed influenza-like illness. There were 86 children recruited; 43 who had undergone HSCT and 43 controls. For the HSCT group, seroprotection and seroconversion rates were 81.4% and 60.5% for H3N2, 41.9% and 32.6% for H1N1, and 44.2% and 39.5% for B strain respectively. There was a significant geometric mean fold increase to the H3N2 (GMFI 5.80, 95% CI 3.68-9.14, p < 0.001) and B (GMFI 3.44, 95% CI 2.36-5.00, p = 0.048) strains. Serological response was superior in age-matched controls to all vaccine strains. There were no serious adverse events following vaccination. For children who underwent HSCT, incidence of laboratory-proven influenza infection was 2.3%. Overall, this study provides evidence to support annual inactivated influenza vaccine administration to children following HSCT.

COVID‐19 vaccination for children with cancer

“…8 There is a paucity of data regarding COVID-19 vaccination in children with cancer; however, these findings have been mirrored by studies of inactivated influenza and pneumococcal vaccination, which reflect that children with cancer are able to mount protective immune responses to vaccination, and that the extent of response is modulated by a variety of factors that can include the number of doses received, whether treatment is being delivered for a solid or hematological malignancy and lymphocyte count at the time of vaccination. [9][10][11] Given that the patterns of response are reflective of host immunity, similar outcomes are likely to be found following COVID-19 vaccination in children with cancer, suggesting that optimization of outcome could be achieved by timing immunization at the furthest point from the immunosuppressing effect of cytotoxic treatment during a given cycle. In addition, a specific consideration to vaccination of children with acute lymphoblastic leukemia is the presence of polyethylene glycol (PEG) as a stabilizing component of mRNA COVID-19 vaccines, necessitating the development and validation of strategies to mitigate risk for children with a prior history of hypersensitivity to PEGasparaginase.…”

Shorter duration of protection and lower geometric mean titers against A/H3N2 antigen of the quadrivalent influenza vaccine in children post-allogeneic hematopoietic stem cell transplantation

“…Previous studies have shown lower prevalence and hospital admission rates in post-HSCT adults immunized with the influenza vaccine compared to those unimmunized [ 3 ]. Although there is a lack of data on children that have undergone HSCT, one study showed superior serologic response compared to age-matched controls for all vaccine strains [ 4 ]. However, there remains a paucity of data on the effectiveness and duration of seroprotection of the influenza vaccine in children, especially those that have undergone HSCT or chemotherapy.…”

Preparing for the 2020—2021 influenza season

“…50,51 noted that all pediatric transplant societies recognize that influenza vaccination is important to prevent severe disease, and recommend its prioritization as soon as possible in the influenza season. 21,52 Providers should note that use of antiviral medication at the time of LAIV (but not IIV) administration may impair response. 26 This is less likely to be a concern for pediatric transplant patients, as live virus vaccines are contraindicated for the majority of transplant recipients.…”

“…Chemoprophylaxis should never be used as a substitute for vaccination—only as an adjunct measure—since immunization has significant benefits for individuals and the population as a whole, including decreased severity of illness if it does occur 50,51 . It should be noted that all pediatric transplant societies recognize that influenza vaccination is important to prevent severe disease, and recommend its prioritization as soon as possible in the influenza season 21,52 . Providers should note that use of antiviral medication at the time of LAIV (but not IIV) administration may impair response 26 .…”