Dear Editor, we would like to discuss on the publication “Concomitant pulmonary and neurological embolisation in a Down patient after SARS-CoV-2 vaccine: what is missing? ^{Reference Di Molfetta, Volpe and Cesario1} ” Di Molfetta et al. mentioned that “Down patients affected by CHD are more prone to develop pulmonary vasculopathy than non-syndromic patients” and discuses on interrelationship with COVID-19 vaccination. The change of blood viscosity and alteration of coagulation system is a possible pathological process following COVID-19 vaccination. ^{Reference Joob and Wiwanitkit2} The patient with underlying heart problem might have a risk for developing thrombotic disorder. However, it should recognise that there is also a possibility of concurrent medical problem that might lead to embolisation. For example, dengue might concomitantly occur in a COVID-19 vaccine recipient ^{Reference Kebayoon and Wiwanitkit3} and might trigger embolisation. ^{Reference Poletto, Cerruti and Spiezia4} Finally, it should discuss on the safety of the COVID-19 vaccine in a patient with underlying cardiac septal defect or vulvular disease. The structural defect in heart might interrupt flow of blood and might trigger thrombotic problem. Nevertheless, the recent report showed that there is no problem on safety of vaccination for patients with underlying rheumatic heart problem. ^{Reference Sattui, Liew and Kennedy5}