The current tally stands at five: not players certain to make the European Ryder Cup team, which might have been the kind of scenario under consideration at this stage of a normal season, but the number of PGA Tour players who have tested positive for Covid-19 after three tournaments in front of no fans since the restart under the Tour’s ‘bubble’.

The Unfortunate Five (in order of disappearance from the circuit for the time being) are Nick Watney, Cameron Champ, Denny McCarthy, Dylan Frittelli and Harris English. It is fair to say that no one expects that to remain the extent of the damage, and considered as a whole it already isn’t. The caddies of Brooks Koepka and Graeme McDowell - respectively Ricky Elliott and Ken Comboy - tested positive for coronavirus last week, causing their players to withdraw from the Travelers Championship.

The latter story is indicative of the flaw that bursts the Tour’s bubble. Elliott and Comboy both attended a funeral in Florida. It seems likely that’s where they got infected. Their players had no alternative except to withdraw given the amount of time they had subsequently spent in close proximity to their bagmen. In addition, Chase Koepka, Brooks’ brother, withdrew, as did Webb Simpson, who had been victorious the previous week at the RBC Heritage tournament in South Carolina and then found a close family member had been infected. Justin Thomas described the environment there as being like a “zoo”, with social distancing by the public on beaches and in restaurants seeming to be a wholly alien concept. What might happen when 8,000 fans will be permitted to attend the Memorial Tournament in a fortnight…well, we shall soon see.

The truth is that other than on the course itself, when they are actually playing golf, the players are in no sort of protective bubble. For example, while the Tour has booked hotel rooms, players do not have to stay there and other people can. So it’s verging on pointless. In fact, even on the course players have been fist-bumping, letting caddies hand them their clubs rather than picking them out themselves as advised, and no one is wearing a mask. In other words, the bubble could spell trouble.

Nothing has occurred that’s as egregious as the behaviour at Novak Djokovic’s recent elite tennis tournament in Serbia and Croatia, where just about every participant has been confirmed as having now got the virus. No PGA Tour players have been photographed in embraces at a nightclub amid this global pandemic. And last week Rory McIlroy brought a sense of calm and perspective at the Travelers Championship.

“I saw there were a couple of calls to shut the tournament down,” he said, “which is silly from my point of view. [Albeit it’s what he said should happen when the Players Championship was abandoned after one round in March because of the virus.] There’s been almost 3,000 tests administered and the percentage of positive tests is a quarter of a per cent.”

Meanwhile, news about the Ryder Cup is thought to be imminent. Since fans cannot be allowed, it is thought likely to be postponed.

You can follow Robert Green on Twitter @robrtgreen and enjoy his other blog f-factors.com plus you can read more by him on golf at robertgreengolf.com