Parents should watch their children for any warning signs to ensure they do not develop an inflammatory condition that can severely affect the heart after being vaccinated against Covid-19, the Department of Medical Services said.
Although extremely rare, Multisystem Inflammatory Syndrome in Children (MIS-C) is seen as an emerging disease and one that could be triggered by the body's immunity response to the novel coronavirus, said Dr Somsak Akkasilp, the department's chief.
If left untreated, it can cause a number of the body's natural systems to malfunction and have a severe impact on the way the heart functions, he explained. Children with chronic diseases such as obesity or diabetes are considered more at risk.
Among children of all ages infected with Covid-19 globally, MIS-C has been found in 0.02% of cases, he said, adding there have been 40 such cases in Thailand.
"I would not say that parents should panic about this, but they should monitor their children," he said.
"If they develop any symptoms, they should immediately seek a consultation at the Queen Sirikit National Institute of Child Health, which is ready to help."
Symptoms typically include fever, redness around the eyes, vomiting, stomachaches, rashes -- and in extreme cases sudden death due to heart inflammation.
So far, eight confirmed cases have been reported to the children's hospital in Bangkok, with their ages ranging from nine months to 11 years. Six stemmed from Covid-19 infections.
All exhibited rashes, fever, vomiting, diarrhoea, red eyes and mouth, and swollen hands and legs. Four are in critical condition with weakening heartbeats, Dr Somsak said.
The Ministry of Public Health plans to provide Covid-19 vaccines to children aged three years and upwards due to the prevalence of the infectious Delta strain.
Inactivated vaccines like Sinovac, which function similar to flu shots, are considered safer for children, according to local paediatricians.