Novak Djokovic missed two Grand Slam tournaments because of COVID-19 vaccination requirements:

• He was denied entry to Australia and missed the 2022 Australian Open after his visa was canceled due to his unvaccinated status

• He was also not allowed to participate in the 2022 US Open for the same reason

In addition, Djokovic missed other major tournaments such as the Indian Wells and Miami Open Masters 1000 events in 2022 and 2023 due to the US COVID-19 vaccination entry rules

. Despite missing these two Grand Slams in 2022, Djokovic continued to compete and win other majors when allowed, including the 2023 Australian Open, French Open, and US Open

. So, in summary, Djokovic missed two Grand Slam tournaments (the 2022 Australian Open and 2022 US Open) because of COVID-19 vaccination policies