Six babies younger than 12 months have been admitted to hospitals in Hamilton and Ottawa because of COVID-19 since the middle of December.
The situation pushed a group of Ontario hospitals to urge pregnant people to get vaccinated against COVID-19.
Toronto's Hospital for Sick Children, McMaster Children's Hospital, the Children's Hospital of Eastern Ontario and Kingston Health Sciences Centre said in a statement all infants admitted to the Children's Hospital of Eastern Ontario in Ottawa had unvaccinated mothers.
The group of hospitals say infants' immune systems have difficulty fighting disease especially without maternal antibodies transferred during pregnancy from vaccination.