Dengue and coronavirus disease 2019 (COVID-19) may share clinical and laboratory features. Reunion Island is a French overseas department located in the Indian Ocean with a population of more than 850,000 inhabitants. Due to its tropical climate, Reunion Island is at risk of arbovirus outbreaks. An increase in the number of dengue cases has been reported on the island since the beginning of 2018, with 3 different serotypes circulating mostly in austral summer. According to the last epidemiological report of March 30, 2020 from Santé Publique France, 3,144 new cases of dengue have been diagnosed since the beginning of 2020 in Reunion Island [1]. On March 2020, the first COVID-19 cases were imported to the island from metropolitan France by airplane. We report the case of an 18-year-old male living in Reunion Island, with no relevant past medical history except occasional migraines. Our patient travelled back from Strasbourg (initial French epicenter of COVID-19) to Reunion Island on March 18, 2020. After his arrival, he returned to his parents' home, respected national confinement guidelines, and only went shopping once. The onset of symptoms occurred on April 3, with fever (39˚C), asthenia, anorexia, and headache. On April 4, he tested positive in the emergency department for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by reverse transcription (RT)-PCR (E gene, RdRP gene, and N gene positive), the causative virus of COVID-19. He was discharged from the emergency room after diagnosis. On April 5, an itchy erythema rash appeared. He came back to the hospital on April 7 for persistent fever (38.7˚C), arthromyalgia, dyspnea with polypnea (respiratory rate of 24 breaths per minute), and itchy maculopapular rash. The dengue rapid test was positive (NS1 antigen+) in the emergency department. Therefore, he was hospitalized the same day in the COVID-19 unit of St Denis University Hospital Center. The physical examination revealed a body temperature of 38˚C, blood pressure of 112/63 mmHg, pulse of 63 beats per minute, and oxygen saturation of 99% in ambient air. He had dry cough (since February) and no chest pain. Pulmonary auscultation was normal. He had no hematuria. He described retro-orbital eye pain and mild photophobia, with anorexia, nausea, and vomiting. He had infracentimetric cervical lymphadenopathies. Skin examination showed a roseoliform maculopapular exanthema of the trunk, limbs, and face, which rapidly evolved into a scarlatiniform-like rash. There were no real intervals of healthy skin but rounded islands of sparing ("white islands in a sea of red") (Figs 1 and 2). There was no mucosal involvement nor hand and feet affection involvement. The itching had stopped, and there was no scratching