Police said the two minors - a four year-old boy and two-year-old girl were admitted on March 15 while their octogenarian grandparents were admitted today.
The Dean of the Hospital Dr Thulasiram said the family might have contracted it from Hyderabad, where they had gone recently to see off their son, who was proceeding to U.S.A.
The family had been admitted to the special ward at the hospital and were being monitored closely, he said
Officials said there are enough medicines in stock at the Hospital for treating swineflu and that those treating the affected family members had been vaccinated.