Supplemental Digital Content is available in the text.

Background Data are limited on the burden of influenza and seasonal influenza vaccine effectiveness (VE) in children with sickle cell disease (SCD). Methods We used a prospectively collected clinical registry of SCD patients 6 months to 21 years of age to determine the influenza cases per 100 patient‐years, vaccination rates, and a test‐negative case‐control study design to estimate influenza VE against medically attended laboratory‐confirmed influenza infection. Influenza‐positive cases were randomly matched to test‐negative controls on age and influenza season in 1:1 ratio. We used adjusted logistic regression models to compare odds ratio (OR) of vaccination in cases to controls. We calculated VE as [100% × (1 − adjusted OR)] and computed 95% confidence intervals (CIs) around the estimate. Results There were 1037 children with SCD who were tested for influenza, 307 children (29.6%) had at least one influenza infection (338 infections, incidence rate 3.7 per 100 person‐years; 95% CI, 3.4‐4.1) and 56.2% of those tested received annual influenza vaccine. Overall VE pooled over five seasons was 22.3% (95% CI, −7.3% to 43.7%). Adjusted VE estimates ranged from 39.7% (95% CI, −70.1% to 78.6%) in 2015/2016 to −5.9% (95% CI, −88.4% to 40.4%) in the 2016/17 seasons. Influenza VE varied by age and was highest in children 1‐5 years of age (66.6%; 95% CI, 30.3‐84.0). Adjusted VE against acute chest syndrome during influenza infection was 39.4% (95% CI, −113.0 to 82.8%). Conclusions Influenza VE in patients with SCD varies by season and age. Multicenter prospective studies are needed to better establish and monitor influenza VE among children with SCD.

Background Vaccination is the primary strategy to reduce influenza burden. Influenza vaccine effectiveness (VE) can vary annually depending on circulating strains. Methods We used a test-negative case-control study design to estimate influenza VE against laboratory-confirmed influenza-related hospitalizations among children (6 months-17 years) across 5 influenza seasons in Atlanta, Georgia from 2012-13 to 2016-17.Influenza-positive cases were randomly matched to test-negative controls based on age and influenza season in a 1:1 ratio. We used logistic regression models to compare odds ratios (OR) of vaccination in cases to controls. We calculated VE as [100% x (1-adjusted OR)] and computed 95% confidence intervals (CIs) around the estimates. Results We identified 14,596 hospitalizations of children who were tested for influenza using multiplex respiratory molecular panel; influenza infection was detected in 1,017 (7.0%). After exclusions, we included 512 influenza-positive cases and 512 influenza-negative controls; median age was 5.9 years (IQR 2.7-10.3); 497 (48.5%) were female, 567 (55.4%) were non-Hispanic Black and 654 (63.9%) children were unvaccinated. Influenza A accounted for 370 (72.3%) of 512 cases and predominated during all five seasons. The adjusted VE against influenza-related hospitalizations during 2012-13 to 2016-17 was 51.3% (95% CI 34.8-63.6%) and varied by season. Influenza VE was 54.7% (95% CI 37.4-67.3%) for influenza A and 37.1% (95% CI 2.3–59.5%) for influenza B. Conclusions Influenza vaccination decreased the risk of influenza-related pediatric hospitalizations by >50% across five influenza seasons.

Background A more complete understanding of the epidemiology, risk factors, and clinical features of cat scratch disease (CSD) in children could help guide patient care. Methods We conducted a retrospective analysis of children presenting to a tertiary pediatric hospital system in Atlanta, Georgia between January 1, 2010, and December 31, 2018 who had serology, PCR and/or cytopathological results consistent with a Bartonella henselae infection. We also retrospectively reviewed veterinary diagnostic results performed at the University of Georgia (UGA) from 2018-2020 to ascertain the burden of bartonellosis in companion animals within the state. Results We identified 304 children with CSD over 9 years with the largest proportion of diagnoses made during August (41/304, 13.5%) and September (47/304, 15.5%). The median age of child cases was 8.1 years (interquartile range (IQR) 5.4-12.1]; 156 (51.3%) were female; 242/262 (92.4%) reported feline exposure, while 55/250 (22%) reported canine exposure of those with exposure histories documented in the medical record. Although lymphadenopathy was present on physical examination in the majority of cases (78.8%), atypical presentations lacking lymphadenopathy were also common (63/304, 20.7%). Among children with radiographic imaging, 20/55 (36.4%) had splenomegaly and 21/55 (38.1%) had splenic and/or hepatic microabscesses. Among veterinary data, Bartonella seroprevalence was 12/146 (8.2%), all among canines, with a geographic distribution that spanned the state of Georgia. Conclusion Distinguishing clinical features of CSD included subacute regional lymphadenopathy in school-aged children in the late summer, almost all of whom had cat exposure. Atypical clinical manifestations of CSD were also commonly identified.