The West Indies team had flown back after playing three T20Is in Karachi last week. Pakistan had made a clean sweep of the series.
Rizwan and Babar put on a 158-run opening stand that set up Pakistan's win with seven deliveries and as many wickets to spare as they recorded their highest successful chase in T20Is.
Pakistan have taken an unassailable 2-0 lead in the three-match T20I series. The third T20I is scheduled to be played on Thursday, followed by three ODIs here.
The remaining matches are on Tuesday and Thursday, also in Karachi. The two sides will also play three ODIs, part of ICC World Cup Super League, on December 18, 20, and 22.
All the four positive persons, who were fully vaccinated and are asymptomatic, will now undergo a period of self isolation for 10 days after which again they will be tested.
West Indies will touch down in Pakistan on December 9 and will feature in three T20Is and as many T20Is, all to be played at the National Stadium in Karachi from December 13 to 22.
West Indies captain Jason Holder and young pacer Oshane Thomas combined to pick seven wickets to bundle Pakistan out for 105.
There is absolutely nothing differentiating Pakistan and West Indies on the back of their recent ODI record.
West Indies lost the three T20Is versus Pakistan by big margins — 143 runs, 83 runs and 8 wickets — with more than three overs to spare.
Pakistan's interior minister has invited the England cricket team to tour the country for the first time since 2005.