HANOI: Microsoft chairman and top philanthropist Bill Gates was in Vietnam on Monday for a low-key visit to study the communist country's lauded childhood vaccination programme, officials said.

The world's richest man, travelling with his wife Melinda, stayed out of the limelight on his first return trip since he was feted like a rock star here a year ago by thousands of university students who idolise the IT messiah.

“They are here on a kind of study tour to learn more about the immunisation programme in Vietnam,” said World Health Organisation country chief Hans Troedsson.

The couple arrived in Hanoi by private jet on Sunday for a three-day visit during which they were also due to meet top government leaders.

On Monday they visited two clinics on the outskirts of Hanoi and chatted with mothers and staff, said Duong Thi Khien, head of the Dong Anh district health centre.

“They wanted to look at vaccination efforts for new-born babies.” Gates' charitable foundation, with a war chest of almost $30 billion donated by the high-tech tycoon, funds HIV/AIDS research and vaccinations against tuberculosis, malaria and other diseases.—AFP