Players from both teams and support staffs will be retested on Friday afternoon now.
ESPNcricinfo reported, "postponement relates to positive Covid-19 tests within the South Africa camp, amid suggestions that protocols were breached during the T20I series."
Players from both teams and support staff personnel are now set for another Coronavirus test on Friday.
"This decision results from a player from the Proteas team testing positive for Covid-19 after the teams' last round of scheduled testing performed on Thursday ahead of the ODIs," Cricket South Africa (CSA) informed via a statement.
"In the interests of the safety and well-being of both teams, match officials and all involved in the match, the acting CEO of CSA, Kugandrie Govender as well as the CEO of the ECB, Tom Harrison, have agreed to postpone the first fixture to Sunday."
Earlier as well, multiple positive tests within the home team camp had brought about a scare on England's tour in the lead-up to the T20I series which, thankfully, went ahead without any problems.
The three-match ODI series is part of the ICC Super League and sees both teams contesting for crucial points in determining their direct participation at the 2023 World Cup in India.
The first ODI will now be played on Sunday (December 6), followed by the second and the third on Monday (December 7) and Wednesday (December 9), respectively.