Inactivated vaccines after hematopoietic stem cell transplantation (HSCT) appear to be safe, and a full vaccination program should be offered to all allogeneic and autologous HSCT recipients, according to the European Conference on Infections in Leukaemia (ECIL) group. Additionally, the group recommended that the use of live attenuated vaccines should be limited to specific situations because of the risk of vaccine-induced disease.

The ECIL group is a joint venture of the Infectious Diseases Working Party of the European Society for Blood and Marrow transplantation (EBMT) and several other vested groups. In a report published in The Lancet Infectious Diseases, the group issued an update on vaccination procedures for all patients with hematologic malignancies, including HSCT recipients. The group conducted a comprehensive literature review to inform the development of these guidelines.

The researchers offered recommendations for using antibacterial inactivated vaccines against various pathogens including Streptococcus pneumoniae, Haemophilus influenzae type b, diphtheria, tetanus, Neisseria meningitides, and Bordetella pertussis. The group also developed guidelines regarding the use of antiviral inactivated vaccines such as inactivated influenza vaccine, inactivated poliomyelitis vaccine, hepatitis B virus vaccine, and human papillomavirus vaccine.

The researchers focused their safety review primarily on pneumococcal and influenza vaccines that were administered to patients after they underwent HSCT in larger prospective trials. Response rates to these vaccines were found to be lower in these patients during the first months after transplant compared with healthy individuals of the same age. However, response improved over time, approaching the same rates as healthy individuals within 24 to 36 months after vaccination. Furthermore, there was no evidence of a difference in adverse event incidence in patients who underwent HSCT compared with healthy controls.

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The researchers noted that vaccination should only be postponed in very specific cases. Because a significant number of patients exhibited a response to immunogenic vaccines as early as 3 months after transplant, the researchers recommended “[starting] crucial vaccinations with inactivated vaccines from 3 months after transplant, irrespective of whether the patient has developed graft-versus-host disease or received immunosuppressants.”

Current research suggests that clinicians should take into account any risks present in specific communities and be aware that vaccines can save lives and avoid unnecessary hospitalizations. Furthermore, the group acknowledged that prospective studies assessing distinct subgroups of patients who received transplants are warranted.

Reference

1. Cordonnier C, Einarsdottir S, Cesaro S, et al. Vaccination of haemopoietic stem cell transplant recipients: guidelines of the 2017 European Conference on Infections in Leukaemia (ECIL 7) [published online February 7, 2019]. Lancet Infect Dis. doi: 10.1016/S1473-3099 (18)30600-5