Three children under the age of 5 have died in Hong Kong’s spiraling COVID-19 outbreak, a disproportionately large number that has local parents anxious, though pediatricians say it could just be a grim coincidence.

While the numbers are too low to draw any conclusions, according to experts, the kids — age 11 months, 3 and 4 years old, respectively — make up nearly 0.3% of the 1,153 fatalities that have occurred in this wave of infections. None had any known underlying health conditions. Their deaths are being investigated by the coroner, according to the Hospital Authority.

The deaths mark a child death rate higher than in countries such as Australia and Singapore, which originally adhered to the same zero-tolerance policy as Hong Kong. Australia has more than 5,300 COVID-19 fatalities, including six in children. No one under age 20 has died from the virus in Singapore during the past year.