Health officials ordered the screening of newborns after a 38-year-old nurse who worked at Gemelli's neonatal ward between March and July tested positive for TB.
The nurse is being treated at another hospital.
It is not clear how or where she became infected, in spite of being vaccinated against TB. ''The children are not ill or contagious,'' said Costantino Romagnoli, the head of Gemelli's neonatal department. ''The tests indicate exposure to the TB bacteria.
The children might develop the disease only if they were not immediately given prophylactic treatment, but they will be''.
Regional officials said the families of the 1,271 babies born between March and July will be contacted by Friday for screening appointments.
Screenings have been stepped up from 25 to 150 per day, in order to reach all babies at risk by the end of August.
It is impossible to predict how many of them will turn up positive, Romagnoli added. A statement with screening results will be issued at 8pm daily, health officials said. Another five-month-old child who tested positive for TB has been admitted to Bambin Gesu hospital, but it is unclear whether her exposure is related to the same nurse.
Lazio regional authorities confirmed that people exposed to TB do not necessarily develop the disease, as long as prophylactic protocols are followed.
''This is not an epidemic,'' said Lazio Governor Renata Polverini.
Health Minister Ferruccio Fazio also said there was no need to panic. ''Millions are exposed every year, but only 4,000 are likely to develop full-blown TB,'' he said.
''It's a completely curable disease.
There is no cause for alarm''. A parliamentary health committee has requested a report from Polverini.