With the first ODI between England and South Africa called off amid a series of positive Covid-19 tests, question marks hang over the rest of the tour. Here we take a look at some of the key issues to be resolved.

What is the current state of the tour?
Having completed the three-match T20I series with relatively little drama, issues surfaced ahead of the first ODI, scheduled for Friday in Cape Town. The game was initially postponed, after a positive Covid-19 test in the South Africa squad, and the Newlands fixture pushed back. However, two more positive tests among staff at the Vineyard Hotel, where both teams are staying, led to Sunday's ODI in Paarl being delayed and then cancelled.

Have there been any further positive tests?
The England camp subsequently revealed that they had returned two "unconfirmed" positives after a round of retesting on Saturday evening. These are awaiting independent ratification, after which the ECB will consult with CSA about the fate of the tour - although no decisions are expected until Monday.

Could the remaining ODIs still be played?
In theory, yes. The rearranged fixture at Newlands has already been moved again, and won't now be played on Monday. But should England's two unconfirmed positives come back negative, then it is possible the ODIs could be played as back-to-back games on Tuesday and Wednesday.

What happens if England's two positive cases are confirmed?
The England players and staff are currently self-isolating in accordance with South African guidelines. Should the presence of Covid-19 be confirmed, those who tested positive would be required to remain quarantined at the hotel for a 10-day period, along with anyone deemed to have come into close contact with them. That would in turn mean missing the chartered flight that is due to take England home on Thursday.

Would that have any knock-on effects?
Aside from unwanted stress and missing out on family time in the run-up to Christmas, some players might find deals to play in the Big Bash League at risk. Sam Billings, Tom Curran, Lewis Gregory, Liam Livingstone and Jason Roy are due to fly to Australia at the end of the series, but already face serving a 14-day quarantine period on arrival. With the BBL starting on Thursday and running through until early February, delays to their departure from South Africa could curtail availability for the tournament.

For those players who are also likely to be in the England Test squad, there is also the looming prospect of a tour to Sri Lanka at the start of next year, scheduled to depart on January 2. If their return to the UK was put back until December 17, they would have little more than two weeks at home before being asked to travel to another bio-bubble for the two-Test series.

How did individuals contract Covid-19 in a bio-secure environment?
This remains unclear. Although South Africa produced two positive tests ahead of the T20I series, those infections likely occurred before the squad came together. Thursday's positive was "a more recent case that occurred within the bio-secure environment," according to CSA medical officer, Dr Shuaib Manjra. CSA said subsequently it had investigated and discounted the possibility of a breach of protocol by the players. However, it is understood that not all of the hotel staff have been staying on site.

What might be the implications for South Africa's summer?
The whole tour was worth around US$4.2m in broadcasting money to CSA, and the loss of half of the fixtures would mean a significant financial hit. Equally damaging, confirmation of a bio-security breach could cast doubt on whether upcoming tours by Sri Lanka, Pakistan and Australia will go ahead as planned.

Will there be any impact on the World Cup Super League?
If the series is cancelled due to the coronavirus, there is the potential for the three fixtures - worth 10 points each - to be rearranged (although few windows in which to squeeze another tour). In the case that the games go down as abandonments, then points would be shared, with South Africa and England taking 15 each.