Table 2. Summary of studies evaluating influenza vaccine among individuals with hemoglobinopathies.

Seroprotection was defined as >1:40 HI titers.

Reference	Location	Population	Vaccine	Findings	Additional information
Steinberg, et al. (1978) [55]	California, United States	Children 4–18 years of age with sickle cell disease	Bivalent influenza A split virus (subvirion)	90% seroprotection following 2 doses	None
Glezen, et al. (1983) [56]	Texas, United States	Children <5 years of age with sickle cell disease	Trivalent inactivated	68–84% of school age children had titers ≥1:32 following 1 dose; 55–73% of preschool age children had titers ≥1:32 following 2 doses	None
Ballester, et al. (1985) [60]	Michigan, United States	Adults with sickle cell disease	Trivalent inactivated vaccine	50% had decreased or undetectable influenza IgM following vaccination	Patients also had decreased splenic function
Souza, et al. (2010) [57]	Brazil	Children 8 years and older and adults with sickle cell disease	Trivalent inactivated virosome-adjuvanted	60–84% seroconversion and 70–100% were seroprotection to all 3 strains	No statistically significant differences between the two vaccines
Souza, et al. (2010) [57]	Brazil	Children 8 years and older and adults with sickle cell disease	Trivalent inactivated split	62–68% seroconversion and 77–98% were seroprotection to all 3 strains
Esposito, et al. (2010) [64]	Italy	Adolescents and adults with β-thalassemia major	Monovalent influenza A(pH1N1)MF59-adjuvanted	87% seroconversion and 100% seroprotection 4 weeks after dose	None
Long, et al. (2012)	New York, United States	Children with sickle cell disease	Monovalent influenza A(pH1N1)	70% seroprotection approximately 6 weeks following vaccination; 79% cell-mediated immunity responses as measured by IFNγ ELLISPOT assay	Hydroxyurea use was associated with lessened HI antibody response
Purohit, et al. (2012) [59]	Florida, United States	Children with sickle cell disease	Monovalent influenza A(pH1N1)	76% seroprotection 8 month after vaccination	Hydroxyurea use was not associated with lessened HI antibody response; chronic transfusions was

HI = hemagglutinin inhibition.