Elderly people, pregnant women, patients with chronic diseases and children planning to take part in the pilgrimage to Mecca, Saudi Arabia, this year should delay the trip until the risk of infection with the H1N1 influenza virus has abated.
During the Hajj, which starts on 25 November, as many as 2.5 million pilgrims will gather at holy sites in Saudi Arabia.
The mass gathering increases the risk of infectious diseases both during the Hajj and afterwards, when pilgrims exposed to infection return home.
Previous years have seen global outbreaks of group-A men- ingococcal disease among pilgrims and their contacts following the Hajj. This year, the main threat is likely to be swine flu.
Other advice for limiting the spread of swine flu among Hajj pilgrims includes ensuring they are informed about the importance of hand hygiene and providing personal hygiene kits.