World health officials are increasingly hearing about cases of an inflammatory disease similar to Kawasaki disease in a few countries, including the United States and Italy, Dr. Maria Van Kerkhove, head of WHO’s emerging diseases and zoonosis unit, said during a news conference at the agency’s headquarters in Geneva.

The WHO said initial reports hypothesized that this syndrome, which can cause high fever and swelling in blood vessels, may be related to Covid-19.

Early in the outbreak, researchers and infectious disease experts said the virus appeared to be sparing children while hitting the elderly and those with underlying health conditions particularly hard.

Since then, researchers have learned much more about the virus, including that children do get it and can die from it, even without underlying conditions that tend to worsen symptoms.

Most kids report mild respiratory symptoms, namely fever, dry cough and fatigue. However, some children can become seriously ill.