Half a dozen visiting Pakistani cricketers likely contracted the coronavirus in their own country before leaving for the tour or during their journey, New Zealand director of public health Dr Caroline McEnlay believes.
McEnlay said even though the travelling Pakistani players have met all COVID-related health protocols before boarding the flight to New Zealand, the deadly virus could have already been incubating inside the bodies of the six cricketers.
"This is possible - it does take a few days after exposure before the disease develops," she told ESPNcricinfo.com.
"Pre-departure testing does help in identifying people who have current infection but it will not detect people who have very recently been exposed to the virus.
"They were required to take a Covid-19 polymerase chain reaction (PCR) test and be symptom-free before departing for New Zealand."
McEnlay said "of the 54 team members that arrived, one team member was symptomatic on arrival in Auckland and was taken to the managed quarantine hotel in Auckland (Jet Park) to be tested."
"The test returned negative. The remaining 53 members flew to Christchurch and to the managed isolation facility at the Chateau on the Park," she added.
The jumbo Pakistani squad flew to New Zealand from Lahore via Dubai, where they changed aircrafts. After landing in Auckland, they boarded a chartered flight to Christchurch.
McEnlay also stated that after initially found guilty of "a number of breaches" of COVID protocols, the Pakistan players and support staff had later fully complied with New Zealand's isolation management policy.
"There have been no further reported breaches," she said.
She also informed that barring one member of the visiting side, all others have been released from the managed isolation facility (MIQ) on Tuesday, after they returned negative.
"One case will remain in the Christchurch quarantine facility until fully recovered," McEnlay said.
"One person repeatedly tested negative and is being released from the Auckland quarantine facility today, where they had been transferred on arrival as a precaution.
"After extensive testing and completion of their time in managed isolation in Christchurch, the Canterbury DHB medical officer of health is satisfied these people pose a very low risk to the community," McEnlay said.
Pakistan are scheduled to play three T20Is and two Tests against New Zealand starting later this month, with the series opener on December 18 in Auckland.