The All England Club has sent home 28 of its Wimbledon staff after they displayed flu-like symptoms.
The organiser is also asking visitors to remain vigilant in their personal hygiene.
A spokesman for the organisation says: “We don’t want to be complacent and have asked these staff to stay at home. Three of the four ball girls and boys who initially displayed symptoms are already back in action.”
Some 6,000 people work at Wimbledon during the championships, so the incident rate is similar to that of London in general, he said.