A study in Japan has found that seizures were a more common symptom among children who contracted the coronavirus when the Omicron variant was predominant than when the Delta variant was predominant.

Researchers from the National Center for Child Health and Development and other institutes examined about 850 cases among children under 18 years of age hospitalized with COVID-19.

Roughly 460 cases were from August to December of last year, when the Delta variant was predominant. Around 390 were from January to March of this year, when the Omicron variant was predominant.

The study shows that 19.6 percent of children aged 2 to 12 years old had fevers of 38 degrees Celsius or higher during the Delta period. This figure more than doubled to 39.3 percent during the Omicron period.

The researchers note that 2.2 percent of children in the same age bracket experienced seizures during the Delta period. This climbed to 9.8 percent during the Omicron period.

The study also shows that the number of children aged 6 or above who had a distorted sense of taste during the Omicron period fell to roughly one-seventh of the figure observed during the Delta period.

The researchers say that although 43 children required oxygen administration or ventilator support, all 50 who had been double vaccinated suffered only mild symptoms.

Shoji Kensuke of the center's infectious diseases division took part in the research.

He said that if children infected with the coronavirus experience seizures, their parents should take them to medical institutions as soon as possible. He said the children risk developing serious symptoms, such as encephalopathy.

Shoji also said parents should consider having their children inoculated against the coronavirus as vaccines have been confirmed effective in preventing serious symptoms in youngsters.