Tension was prevailing at Niloufer Children’s Hospital in Hyderabad where 32 infants were undergoing treatment in intensive care unit (ICU) — three of them on ventilator support — even as doctors were closely monitoring their condition. Two infants had died and others developed serious complications when they were given wrong medicine after they were administered pentavalent vaccine.

Those who died included two-month old Mohammad Umer and one-and-a-half-month-old Mohammad Faizan.

Doctors said that the next 48 hours will be crucial for the affected children. The nurses at the Urban Health Centre had erroneously given them tramadol, an analgesic opioid drug, instead of paracetamol as children normally develop fever after vaccination.

Doctors attending to the children have reportedly administered an antidote, naloxone, to reverse the effect of tramadol.

Dr Murali Krishna, superintendent of Niloufer Hospital, said: “All affected children are in ICU and doctors are closely monitoring their condition. They are stabilising. It will take 48 to 72 hours for the effect of the drug to come down. Till then we will monitor strictly.”

According to doctors, whenever pentavelant vaccine is given to infants to protect them from infections such as diphtheria, tetanus, pertussis, hepatitis B and haemophilus influenza type B, they are also given paracetamol.

But on Wednesday, a scheduled day for vaccination, when there was a rush of families to get infants vaccinated at the busy health centre, nurses apparently got confused by similar colours of the pills and ended up inadvertently administering the much stronger Tamadol — which is usually given to adult patients as a pain-killer after surgery.

With the death of two of the infants and conditions of four other children turning serious, worried staff members at the health centre summoned the families of all the other children who were given the vaccine and the medicine and advised them to rush to Niloufer Children’s Hospital for follow-up.

Apprehending trouble, authorities at Niloufer Hospital sought police protection. A posse of 80 policemen were deployed in and around the hospital as anxious parents waited for an update on their wards.