Seven Pakistan players and a team masseur have tested positive for coronavirus, but officials say plans to tour England remain "very much on track".
The announcement of the positive results on Tuesday came a day after three others from Misbah-ul-Haq's squad were confirmed as having COVID-19.
All 10 infected players have been ordered to self-isolate and will stay at home when the rest depart on a chartered flight, the Pakistan Cricket Board (PCB) said.
England and Pakistan are due to play three Tests and three Twenty20 Internationals from the end of July until September.
The PCB said the latest seven players to test positive were Fakhar Zaman, Imran Khan, Kashif Bhatti, Mohammad Hafeez, Mohammad Hasnain, Mohammad Rizwan and Wahab Riaz, along with masseur Malang Ali.
In a statement, the PCB said its medical panel was "already in contact with these players and the masseur, who have been instructed to observe strict quarantine at their homes for their and their families' wellbeing".
None showed any symptoms before being tested, the PCB added. They must each produce two negative test results before being allowed to travel to England to join up with the squad.
Ashley Giles, the England and Wales Cricket Board (ECB) director of men's cricket, had said the first three positive tests were "a concern".
Players and staff who have tested negative will gather in Lahore on Wednesday before undergoing a further round of coronavirus testing on Thursday. More tests will be conducted by the ECB once the squad arrives in England.
PCB chief executive Wasim Khan said: "The tour to England is very much on track and the side will depart as per schedule on June 28.
"Fortunately, all the first-choice red-ball squad, barring Mohammad Rizwan, are negative, which means they can start training and practicing immediately after they have been tested and given the all-clear when they arrive in England.
"In the meantime, Misbah-ul-Haq is reviewing the training schedule in England and firming up plans for reserve players to be tested as a back-up."