South Africa's limited-overs tour of Sri Lanka in June has been postponed due to the ongoing spread of coronavirus.
The Proteas were due to visit the island for three Twenty20s and three one-day internationals, the latter series forming part of the International Cricket Council's new one-day league.
"It is very sad that we have been forced to take this step and we will re-schedule the tour as soon as cricket returns to a sense of normality and our international fixture list allows," said Dr Jacques Faul, acting chief executive of Cricket South Africa.
"Our Proteas would not have been able to prepare properly taking our own lockdown situation into account and, more importantly, health considerations for our players, which are always paramount, were the over-riding factor.
"It would have been a particularly important tour for us with the three ODIs counting for the new ICC one-day league and the T20 programme being part of our preparation for the ICC Men's T20 World Cup scheduled for Australia later this year."
World number one Novak Djokovic's opposition to vaccines could stand in the way of his return to tennis once it resumes from the coronavirus pandemic.
A push is growing for all players to be vaccinated when tennis starts again, provided a vaccination is produced by then.
Andy Murray's former coach Amelie Mauresmo last month said tennis should not resume unless players can be vaccinated, although the scientific community has repeatedly said that may be a year away, if a vaccine is developed at all.
"Personally I am opposed to vaccination and I wouldn't want to be forced by someone to take a vaccine in order to be able to travel," Djokovic said in a live Facebook chat with several fellow Serbian athletes on Sunday.
"But if it becomes compulsory, what will happen? I will have to make a decision.
"I have my own thoughts about the matter and whether those thoughts will change at some point, I don't know.
"Hypothetically, if the season was to resume in July, August or September, though unlikely, I understand that a vaccine will become a requirement straight after we are out of strict quarantine and there is no vaccine yet."
Dual grand slam winner Mauresmo last month tweeted: "International circuit = players of all nationalities plus management, spectators and people from the four corners of the world who bring these events to life. No vaccine = no tennis."