H1N1 Influenza among Hematological Patients: Monocentric Influenza Cases from 2011 to 2016

Dear Editor, We read with interest the paper by La Torre et al., 1 which conducted two systematic reviews and a meta-analysis to summarize the results of scientific works about influenza and pneumococcal vaccines in onco-hematological patients. We paid specific attention to influenza vaccine results. The protection rate of H1N1 vaccine resulted in 31% and 30% after the first dose and booster dose, respectively. Protection rate of H3N2 and influenza B first dose was 42.6% and 39.6%, respectively. Considering the response rate, the pooled prevalence for H1N1 was 30% and 35% after the first dose and booster dose, respectively. The response rate for H3N2 was 21.7% after first dose and 24% after booster dose. Finally, the response rate for influenza B was 23.6% after the first dose and 29% after booster dose. Only a minority of patients experienced adverse events, most of them were mild and did not require treatment. Even though influenza vaccine elicits a low response rate among oncohematological patients, particularly in those who received transplantation, splenectomy or rituximab, it is an inexpensive intervention with few side effects. However, the first vaccine dose induces a small response, and the booster dose induces additional antibodies. Therefore, it is recommended to vaccinate these patients twice, 2