People walk along Harajuku's famous Takeshita Street in Tokyo's Shibuya Ward, on March 28, 2020. (Mainichi/Kimi Takeuchi)

TOKYO -- Experts in Japan are warning that young people are also susceptible to fatal cases of the new coronavirus, as reported overseas, amid the rising number of infections among youths.

According to BBC and other news sources, 21-year-old British woman Chloe Middleton died of COVID-19 on March 21. Her family pleaded for people to take the pandemic seriously through Facebook posts, with her mother saying, "To all the people that thinks it's just a virus, please think again." Another family member wrote, "The reality of this virus is only just unfolding before our very eyes."

Also in Britain, a 13-year-old boy died on March 30 after testing positive for the new coronavirus. He passed away just four days after he was admitted to a hospital. According to reports, the boy had no underlying illnesses. He is believed to be the youngest COVID-19 victim in the country.

The virus is not just hitting the young population in Britain. News agency Agence France-Presse (AFP) reported that a 16-year-old girl in France died on March 26 of COVID-19. It was about a week after she started mildly coughing. Her family told AFP that they had heard that the new coronavirus wouldn't affect young people and that they believed it.

In the U.S., an infant under the age of 1 in Illinois who tested positive for the virus has died. The state's health authorities are investigating the case to determine the exact cause of the baby's death.

Meanwhile in Japan, there have been no reports of coronavirus-related deaths in younger generations, but the number of infected youths has been steadily climbing. According to the Ministry of Health, Labor and Welfare, by March 30 infections had been confirmed in 22 children aged 9 and younger, 24 between the ages of 10 and 19, and 222 people in their 20s. A group infection was confirmed on March 30 among Kyoto Sangyo University students who are in their 20s, and the Yamanashi Prefectural Government in central Japan announced on April 1 that an infant just a few months old who had tested positive for the new coronavirus developed a severe case of pneumonia and was being treated in an ICU.

Data also shows young people falling gravely ill after contracting the virus. According to study results released by the U.S. Centers for Disease Control and Prevention in March, of 508 coronavirus patients admitted to hospitals, those aged 19 and younger made up less than 1%, but patients aged between 20 and 44 accounted for some 20%. Furthermore, of 121 patients who required treatment in ICUs, 12% were in the latter age group.

In large-scale research conducted in China, whose data was released in February, while the overall fatality rate of COVID-19 stood at 2.3%, it dropped to 0.2% among patients aged between 10 and 39. However, Dr. Shigeru Omi, a member of the Japanese government's expert panel on coronavirus countermeasures, points out that young people and children do have a risk of developing severe symptoms from COVID-19.

Pediatrician Dr. Norio Sugaya at Keiyu Hospital in Yokohama, who is knowledgeable about infectious diseases, said, "If everyone at a school with 1,000 students gets infected, two are estimated to die. It's a very terrifying virus." He added, "If the number of cases continues to increase, severe symptoms and even deaths could happen in young patients in Japan too."

Dr. Kiyosu Taniguchi, director of the clinical research department at the National Mie Hospital in western Japan, also calls for young people to avoid "the three conditions" where risks of infections are high -- a place with poor air circulation or ventilation, congested spaces and having close contact with other people.

(Japanese original by Yuki Ogawa and Eri Misono, Lifestyle and Medical News Department)