BUDAPEST, Feb 11 (Reuters) - Hungary expects to receive 500,000 doses of Chinese Sinopharm’s vaccine next week and plans to start vaccinations with them soon, Hungarian Prime Minister Viktor Orban’s chief of staff said on Thursday. Gergely Gulyas also told a government briefing that Hungary had decided to launch a document proving coronavirus immunity for those who had been inoculated, those who have recovered from the infection and those who take a blood test proving the presence of antibodies. (Reporting by Krisztina Than and Anita Komuves; Editing by Alison Williams)