It is recommended to provide hepatitis A vaccine to all individuals with hemophilia; however, intramuscular (IM) injections should be avoided in patients with bleeding disorders. There is limited data showing that subcutaneous (SC) route immunogenicity is comparable to the IM route.

A randomized study recently published in the journal Vaccine compared the immunogenicity, long-term protection and safety of SC hepatitis A vaccine with the IM route in 78 children and adults with hemophilia and other bleeding disorders.

Serology was done in 38 patients following the first vaccine dose, and showed seroconversion rates of 83.3% and 90.0% for the SC and the IM group, respectively (p = 0.5). Median IgG CO/OD value for the SC group was nearly two-fold, compared with the IM group (4.4 vs. 2.6, p = 0.2). After second dose, seroconversion rates for the SC and IM groups were 97.5% and 97.4% (p = 1.0). Of the two patients who did not have seroconversion, interval between vaccine dose and serology was one and two days for the SC and the IM group, respectively. In the subsequent routine antibody dosage, they demonstrated seroconversion (100% for both groups). Median IgG CO/OD value for the SC group was 72.5 compared to 58.0 for the IM group (p = 0.2). In a median of nine years after second vaccine dose, median IgG S/CO value for the SC group was 7.6 compared to 7.4 for the IM group (p = 0.8). No serious adverse events were noted in any of the groups. About 12.5% patients in the SC group and 18.4% in the IM group reported adverse events (p = 0.5). About 15.8% patients of the IM group had clotting factor concentrates need for adverse events compared to 7.5% of the SC group (p = 0.3).

SC administration of hepatitis A vaccine was thus found to be as immunogenic, long-term protective and even safer than the IM administration.

Source: Nakasone M, Lopes MH, Sartori AMC, et al. Immunogenicity, Long Term Protection and Safety of Subcutaneous Administration of Hepatitis A Vaccine in Patients With Hemophilia and Other Bleeding Disorders: A Randomized Study. Vaccine. 2020 May 27;38(26):4162-4166.