"winterwhite" Once the virus starts to spread without constant restraint, it infects more people in each of its generations. It is like the old story of the king who rewarded someone who helped him, by promising him gold - one piece for the first square on a chessboard, double that on the next, doubled again on each subsequent square. By the time the board was covered, the king had to give away all the gold in the kingdom, and was bankrupt. 1, 2, 4, 8. 16. 32. 64. 128, 256, 518, 1,036, 2,072, 4,144, 8,288, 16,576, 33,152 - and that is just the first sixteen squares of the sixtyfour on the chess board. It would be the first sixteen generations of infection by the virus. That takes about a week on average to pass on to the next person, so if each person infected two others, sixteen generations would take about four months to spread from one to more than 40,000 people.