They are from 10 countries: Iceland, Cabo Verde, Switzerland, The Bahamas, Qatar, Estonia, Grenada, Gambia and Malta.
Until now, the Vatican authorized only private pilgrimages.
Greta traveling to Rome to meet Pope Francis, speak before the Senate and encourage Italian students to work against climate change.
The Vatican will welcome Salva Kiir, the country's president and his opponent Riek Machar for a spiritual retreated.
