A Briton infected with the coronavirus and 18 fellow tourists were tracked down and offloaded from a plane that would have taken off with 290 passengers for Dubai in just over 15 minutes from an airport in Kerala on Sunday morning.

A large-scale overnight operation by the Kerala government prevented what is being viewed as a clandestine departure bid. But the suspected attempt by the group to leave before a test result was delivered has posed another enormous challenge to the state machinery in tracing possible “contacts” of the tourists after they drove out of a resort in the picturesque Munnar in the southern state.

The incident prompted the state health minister to stress the collective nature of the battle against the virus and underline how a single lapse in vigil by one agency can have disastrous consequences.

Officials suspect that the British tourists tried to leave in haste probably after realising that Saturday’s test result could hobble their travel plans. The tourist who eventually tested positive had fever and had provided samples to a hospital in the state.

The test result came around noon. But before health officials could arrive to isolate the patient and his wife, and quarantine the rest, the entire tourist group had left the Tea County resort in Munnar in the afternoon.

Within hours, the state government had activated the police and health departments and alerted every district administration to watch all the potential travel routes to the Kochi airport.

Somehow, the 19 tourists still slipped through the dragnet and even through airport security and immigration — whose roles are being probed — to board the flight.

Eventually, health department and Ernakulam district officials arrived at the airport and got all the 290 passengers aboard Emirates’ Flight EK531 off the plane shortly after 9am, an airport source said. The flight was scheduled for departure at 9.20am.

A few days earlier, the infected tourist had travelled from Munnar to the Government Medical College Hospital in Kottayam after developing fever, and left a blood sample and a throat swab that tested positive on Saturday morning.

After being taken off the plane, he and his wife were sent to an isolation ward at the Government Medical College Hospital in Kalamassery. The remaining 17 tourists have been quarantined at a private hotel in Kochi that was already empty.

One other passenger, who had apparently “got exposed” to the infected man in the flight cabin, volunteered to be taken off the plane and was put “under observation”.

Health workers disinfected the entire departure terminal and the aircraft before allowing the flight to take off at 12.47pm with 270 passengers.

Kerala is already paying a high price for alleged irresponsible behaviour by a Malayali family of three who had returned from Italy but went about their business as usual without disclosing that their journey had begun from the virus-affected European country.

Three patients who had tested positive initially in Kerala had been cured and discharged from hospital and there was no other recorded coronavirus case in the state till the family that returned from Italy went on the free run. Since then, a second round of infections has been recorded with the count of confirmed cases touching 21 on Sunday evening.

On Sunday, health minister K.K. Shailaja alleged a “major lapse” on the part of the manager of the resort, who has been detained for questioning. The resort was shut down on Sunday. It had no other guests at the time.

“The resort manager shouldn’t have let them leave without the administration’s clearance. The chief minister has ordered a detailed investigation,” Shailaja told reporters.

It remained unclear who had arranged the minibus for the group to travel to the airport, 100km away.

Another mystery is why the tourists had reached the airport only at 2.45am — as security camera footage has established, according to an airport source — after leaving Munnar in the afternoon.

It opens up the possibility of the group having stopped over at some other location — increasing the chances of making “contacts” — while eluding the state-wide administrative alert.

For now, the authorities are trying to track down the minibus driver and helper and put them under observation along with the resort staff and any other guest who may have stayed there since the British tourists arrived on March 10.

The group had arrived on Emirates’ Flight EK530 from Dubai on March 6 and were granted visas-on-arrival at the airport immigration.

They spent the first two days on Kochi Island, a popular beach destination. They then travelled to Athirappally and Cheruthuruthy in Thrissur, spending two days there before driving to Munnar.

After one of them developed fever, he first consulted a doctor at the Tata Hospital in Munnar. From there he was taken to Kottayam to be tested. Health officials then quarantined him and his wife in their room at the Munnar resort till the test report arrived.

Agriculture minister V.S. Sunil Kumar, who visited the airport on Sunday, said: “We got information about the British tourists checking in at the airport and launched an operation with the help of airport security and immigration.

“We could see their movement on the airport security camera network. Some CISF officials (who handle airport security) will be quarantined as a precaution.”

Kumar used the incident to issue a warning: “We need to realise that this (the battle against the virus) requires several departments to work in close coordination. So, even a minor lapse from one department would lead to a situation like this.”

He hinted that departure protocols would be tightened. “Usually we focus on arrivals and not so much on departures. But now we will have to monitor the departing passengers as well,” he said.

Shailaja, during her daily briefing, said a doctor who had recently returned from Spain had tested positive, taking the number of confirmed coronavirus patients under treatment in the state to 21.