Parvovirus B19 infection causes transient aplastic crisis in sickle cell disease (SCD) due to a temporary interruption in the red blood cell production. Toxicity from hydroxyurea includes anemia and reticulocytopenia, both of which also occurring during a transient aplastic crisis event. Hydroxyurea inhibits proliferation of hematopoietic cells and may be immunosuppressive. We postulated that hydroxyurea could exacerbate parvovirus B19-induced aplastic crisis and inhibit the development of specific immune responses in children with SCD. We conducted a retrospective review of parvovirus B19 infection in 330 children with SCD. Altogether there were 120 known cases of aplastic crisis attributed to parvovirus B19 infection, and 12% of children were on hydroxyurea treatment during the episode. We evaluated hematological and immune responses. Children with HbSS or HbSβ0-thalassemia treated with hydroxyurea, when compared with untreated children, required fewer transfusions and had higher Hb concentration nadir during transient aplastic crisis. Duration of hospital stays was no different between hydroxyurea-treated and untreated groups. Children tested within a week following aplastic crisis disease were positive for parvovirus-specific IgG. Immune responses lasted for the duration of the observation period, up to 13 years after transient aplastic crisis, and there were no repeat aplastic crisis episodes. The frequencies of parvovirus-specific antibodies in all children with SCD increased with age, as expected due to the increased likelihood of a parvovirus exposure, and were comparable to frequencies reported for healthy children. Approximately one-third of children had a positive parvovirus B19-specific IgG test without a documented history of transient aplastic crisis, 64% of them were treated with hydroxyurea. Hydroxyurea may reduce requirements for blood transfusions and may attenuate symptoms during transient aplastic crisis episodes caused by parvovirus B19 infections. Children with SCD, whether treated or untreated with hydroxyurea, generate sustained and protective parvovirus B19-specific immune responses.

Introduction Human papilloma virus (HPV) infection can cause cervical, anal, penile, vaginal, and oropharyngeal cancer. The CDC recommends HPV vaccination as a 2 or 3-dose series at <15 or ≥15 years, respectively. Completion of the vaccine series decreases rates of cervical cancer in young women by 29%(Guo, F. et al. American Journal of Preventive Medicine 2018). For this reason, focus is currently on vaccinating younger patients to optimize benefit. Historically, adolescents have had low rates of completion of the HPV vaccine series. African Americans, in particular, have significantly lower rates than whites in receiving the full series (De, P. and H. Budhwani. Public Health 2017). Vaccine hesitancy in sickle cell disease (SCD) patients exists and is exemplified by a lower uptake in teenagers with SCD compared to non-SCD counterparts (Beverung, L. et al. American Journal of Hematology 2018). However, completion of 23-pneumococcal vaccine polyvalent (PPSV-23), which is routinely administered as a series during well-child visits, has notably been high. SCD programs serve as medical homes where primary care may also be provided. With this in mind, we introduced a quality improvement (QI) intervention to improve the uptake of HPV vaccination in the adolescent SCD clinic. A bundle intervention was developed including 1) provider education about HPV vaccination importance, 2) nurse review of each adolescent's vaccine records prior to clinic visit, 3) provider notification by the nurse regarding the need for HPV during the visit, 4) discussion of the vaccine benefits with the family, 5) provision of the vaccine in the SCD clinic after parent consent, and 6) offering of MOC points as incentive to providers for project participation. We sought to evaluate the impact of the QI bundle on completion of the HPV vaccine series. We hypothesized that implementation of the QI bundle would increase the rate of completion of the HPV vaccine series among adolescents with SCD. Secondary objectives included association between completion of the HPV vaccine series and frequency of outpatient visits to the SCD clinic, quality of life (QoL), SCD-specific knowledge, completion of the PPSV-23 series, and markers of socio-economic status (SES). Methods Retrospective data was collected using the Sickle Cell Clinical Research and Intervention Program (SCCRIP) study database (Hankins JS, et al. Pediatr Blood Cancer 2018). Patients aged 12-18 years between October 1, 2018 and December 31, 2019 with any SCD genotype and who were enrolled on the SCCRIP study were included in analysis. The following variables were extracted: age, sex, race, ethnicity, age, economic hardship index (EHI), parental education level, household income, genotype, SCD-specific knowledge, and distance to healthcare facility. The prevalence of completed HPV series, defined as 2 doses ages <15 years and 3 doses ages ≥15 years, in the 12 months prior to implementation of the bundle vaccination program (before October 1, 2018) and after implementation of program (October 2, 2018 to December 31, 2019) was calculated using Fisher's exact. Demographic characteristics and QoL were compared between patients who completed the vaccine series and those who did not. Results In total, 373 patients met inclusion criteria. Their median age was 15.2 (range 12-19), 50% were female, 225 (60.3%) had HbSS/Sβ 0-thalassemia, and 114 (29.7%) had HbC/Sβ +-thalassemia. The mean SES index was 70% (±27%) and the mean QoL score 73 (±14.6). HPV vaccine completion rates increased from 31% to 56.2% after the bundle implementation (Figure 1, p<0.01). Completion of the series was associated with higher SES index, completion of the PPSV-23 series, and higher frequency of outpatient visits. There was no significant association between completion of the vaccine series and QoL, distance from healthcare facility, and disease-specific knowledge (Table 1). Discussion Prevention of communicable diseases such as HPV is imperative in the general population. However, baseline vaccination rates in adolescents with SCD is low. A QI intervention that includes provider education and incentives, active verification of HPV vaccination status, and promotes coordinated communication between the nurse, providers, and patients effectively increased completion of the HPV vaccine series among adolescents with SCD. Continued strategies are needed to further increase the rates of vaccine completion. Figure 1 Figure 1. Disclosures Hankins: Vindico Medical Education: Consultancy; Global Blood Therapeutics: Consultancy; UpToDate: Consultancy; Bluebird Bio: Consultancy.