In this study, we found no increased risk of purpura and hemorrhagic disease, myocarditis/pericarditis in children with CKD who received BNT162b2 vaccine. The COVID-19 vaccine is the most important measure to prevent severe SARS-CoV-2 infection in children with risk factors [10]. A previous study showed that the children with CKD presenting with moderate-to-severe COVID-19 are at risk of severe complications, including severe acute kidney injury and mortality [11]. However, limited data on vaccine safety in children with CKD were available. Similar results were found in previous studies in Asia [12], in U.S. [13], and in European countries [14]. Children with CKD were reported to have a higher risk of serious COVID-19 compared to otherwise healthy persons [11]. In our data, among 1282 vaccinated children with CKD, 3 had a record of myocarditis and/or pericarditis during the observation period. However, when we compared the risk of occurrence of 2 myocarditis/pericarditis in 641 CKD patients without vaccination history, no increased risk was observed, suggesting that vaccination did not increase the risk of heart complication in children with CKD.
In the real-world setting, misinformation about the safety of COVID-19 vaccines can lead to vaccine hesitancy, causing low vaccination rates and increasing the risk of infection especially for children with underlying disease [2]. Because of this, there had been vaccine hesitance among parents of children with CKD. In a previous study, 64% of parents of children with CKD revealed that they were worried of COVID-19 vaccine's safety [3]. In sum, 30% of our children with CKD were not vaccinated likely due to various concerns about vaccines. As a previous survey showed a significant association between self-reported sufficiency and credibility of vaccine-related information [15], the findings of this study may aid in parental decision-making regarding COVID-19 vaccination for their children with CKD.
Despite evidence from clinical trials that focused on healthy adults, a real-world safety data is needed for children with underlying diseases. Although the children with CKD are at higher risk of complications if infected SARS-CoV-2, there is a public health gap to address this low vaccine coverage, likely due to vaccine hesitancy. Based on our result, vaccination is a safe intervention to prevent COVID-19 in children with CKD; hence the benefits of vaccination in this population must be emphasized. To the best of our knowledge, this is the largest safety data of BNT162b2 in children with CKD. This finding can contribute to pediatrician's and parent's understanding of the safety profile of BNT162b2 vaccine for children with CKD.
This study has number of limitations. First, our dataset does not have detailed clinical data, and we were unable to further stratify the analysis by the disease severity. Second, although the data we used covers all healthcare utilization records in Korea, we were unable to include data for prescriptions not reimbursed by the national health insurance. Third, our results of the risk period of 0–60 days might indicate a healthy vaccinee effect. Despite these limitations, the population-representativeness of data and important public health implications is a main strength of this study.
In this national cohort study among children with CKD in Korea, we found no evidence of increased risk of adverse events following BNT162b2 vaccination. Our results provide the safety profiles of COVID-19 vaccine for patients with CKD and highlight the importance of vaccination to prevent potential severe outcomes if infected.