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ABSTRACT Background While vaccination is a key strategy to mitigate the severity of coronavirus disease 2019 (COVID‐19) in children, the risk factors for symptomatic, medically attended (hereon referred to as “symptomatic”) COVID‐19 and the impact of vaccination are not well defined among pediatric solid organ transplant recipients (PSOTR). Methods PSOTR aged six months through 21 years at 11 centers in the Pediatric Infectious Diseases Transplant Network (PIDTRAN) were analyzed retrospectively for symptomatic COVID‐19 between July 2021 and May 2023. Using a Cox proportional hazards model, risk factors associated with COVID‐19‐associated hospitalization, in‐hospital oxygen use, mechanical ventilation, and the impact of COVID‐19 vaccination were analyzed. Results Of 1370 PSOTR, 410 (29%) had symptomatic COVID‐19 infection. Among those with symptomatic infection, 115 (28%) were hospitalized, 35 required in‐hospital oxygen, and three required mechanical ventilation. In the study, 45% were unvaccinated against COVID‐19. Compared to unvaccinated PSOTR, incompletely vaccinated PSOTR had 56% lower hazard (95% CI 0.26, 0.72, p = 0.001) of COVID‐19‐associated hospitalization whereas completely vaccinated did not have a statistically significant difference in hazard of hospitalization. Receipt of at least one dose of the bivalent vaccine was also associated with 92.5% lower hazard (95% CI 0.010, 0.55, p = 0.011) of hospitalization. Risk factors for hospitalization included chronic kidney disease, underlying heart disease, neurodevelopmental delay, and lymphocytopenia. Conclusions Most PSOTR with symptomatic COVID‐19 did not require hospitalization or respiratory support. Several comorbidities and lymphocytopenia are associated with severe COVID‐19 in PSOTR. COVID‐19 vaccination, mostly, protected PSOTR against COVID‐19‐associated hospitalization, but vaccine uptake among PSOTR was low. image

AbstractHuman herpesvirus 6 (HHV‐6A and HHV‐6B) can cause primary infection or reactivate from latency in liver transplant recipients, which can result in a variety of clinical syndromes, including fever, hepatitis, encephalitis and higher rates of graft dysfunction as well as indirect effects including increased risks of mortality, CMV disease, hepatitis C progression and greater fibrosis scores. Although HHV‐6 infection is currently diagnosed by quantifying viral DNA in plasma or blood, biopsy to demonstrate histopathological effects of HHV‐6 remains the gold standard for diagnosis of end‐organ disease. HHV‐6 reactivation may be restricted to the infected organ with no evidence of active infection in the blood. HHV‐6 infections in liver transplant patients are mostly asymptomatic, but clinically significant tissue‐invasive infections have been treated successfully with ganciclovir, foscarnet or cidofovir. Inherited chromosomally integrated HHV‐6 (ciHHV‐6), in either the recipient or the donor organ, may create confusion about systemic HHV‐6 infection. Recipients with inherited ciHHV‐6 may have an increased risk of opportunistic infection and graft rejection. This article reviews the current scientific data on the clinical effects, risk factors, pathogenesis, diagnosis and treatment of HHV‐6 infections in liver transplant recipients.