The Saudi Ministry of Health published its health requirements for travelers to the Kingdom of Saudi Arabia for the pilgrimage to Mecca -- Hajj. The ministry says the annual pilgrimage, which occurs during a five-day period during \"Dhul-Hijjah,\" the final month of the Islamic calendar, is the world\'s largest annual mass gathering, attracting 2 million to 3 million pilgrims every year. Travelers are urged to read the guidelines in their entirety in the Journal of Infection and Public Health, which include: -- All travelers arriving from countries or areas at risk of yellow fever must present a valid yellow fever vaccination certificate showing that the person was vaccinated at least 10 days previously and not more than 10 years before arrival at the border. -- Visitors arriving for the purpose of Umra or pilgrimage or for seasonal work are required to produce a certificate of vaccination with the quadrivalent (ACYW135) vaccine against meningitis issued not more than 3 years previously and not less than 10 days before arrival in to Saudi Arabia. -- All travelers arriving from polio-endemic countries and re-established transmission countries should receive one dose of the oral polio vaccine. -- International pilgrims should be vaccinated against seasonal influenza before arrival in Saudi Arabia, with World Health Organization approved strains specific to the northern or southern hemispheres. -- Hajj and Umra performers are not allowed to bring fresh food in to Saudi Arabia, only properly canned or sealed food or food stored in containers with easy access for inspection. -- Updating immunization against vaccine-preventable diseases is strongly recommended.