The emergence of a coronavirus illness not previously seen in humans, now called coronavirus disease 2019 (COVID-19), has captured the attention of the US and the world. The virus was first identified in Wuhan, China, after an outbreak of pneumonia of unknown cause was identified in December 2019, with most early cases reporting exposure to a live animal market. On December 31, 2019, China reported the outbreak to the World Health Organization, and shortly thereafter, the responsible pathogen was identified as a novel coronavirus, which is called SARS-CoV-2 because of its sequence similarity to the virus causing severe acute respiratory syndrome (SARS). The situation of COVID-19 is evolving rapidly with increasing numbers of cases and involved countries. On January 30, 2020, the World Health Organization declared the novel coronavirus outbreak a public health emergency of international concern, and on March 11, 2020, the outbreak was declared a pandemic. As of March 25, 2020, more than 425 000 cases have been confirmed globally in 170 countries and regions, including more than 55 000 cases in the United States.¹

Coronaviruses cause a wide range of illness, ranging from the common cold to severe, fatal illness. Three coronaviruses causing severe illness in humans have emerged in the past 20 years: the virus causing SARS, which emerged in China in 2002; the virus causing Middle East respiratory syndrome (MERS), which emerged in the Arabian peninsula in 2012; and the virus causing COVID-19.² Common manifestations of COVID-19 in adults include fever, cough, myalgia, shortness of breath, headache, and diarrhea. Based on data from more than 72 000 patients from China, most (81%) were mildly affected, 14% had severe manifestations (eg, with dyspnea or blood oxygen saturation ≤93%), and 5% were critically ill (eg, with respiratory failure or septic shock).³ Risk factors for severe illness were older age and underlying illnesses. The case fatality rate in China was 2.3%,³ although this number might be an overestimate because mild or asymptomatic cases might have been missed. Transmission of COVID-19 is thought to be primarily through respiratory droplets formed when a person with an infection coughs or sneezes, which can be inhaled by contacts within close range (within 6 ft), who then become infected. Other types of transmission (eg, transmission from fomites, fecal-oral transmission) might be possible. The median incubation period is 5 days (range, 2-14 days). At this time, care of patients with severe illness is supportive, since US Food and Drug Administration–approved therapeutics are not available. Although vaccine development is ongoing, it is expected that a vaccine will not be ready for wide distribution for at least a year.⁴

Children are typically more susceptible to influenza complications, yet so far, they have experienced lower-than-expected rates of COVID-19 disease, and deaths in children appear to be rare. In more than 72 000 total cases from China, 1.2% were in patients aged 10 to 19 years, and even fewer (0.9%) were in patients younger than 10 years.³ Only 1 death in this study was in the adolescent age range, and no children in the age range of 0 to 10 years died. In a separate analysis of 2143 confirmed and suspected pediatric cases from China, infants were at the highest risk of severe disease (10.6%), compared with older children (4.1% for those aged 11 to 15 years; 3.0% in those 16 years and older).⁵