Overheard on the interwebs:

Ok, it's really quite simple. The third dose increases immunity, so after the fourth dose, you'll be protected. Once 80% of the population has received the fifth dose, the restrictions can be relaxed as the sixth dose stops the virus from spreading. I am confident that the seventh dose will solve our problems and we'll have no reason to fear the eighth dose. The clinical phase of the ninth dose will confirm that the antibodies remain stable after the tenth dose. The eleventh dose will ensure that no new mutations will develop, so there is no longer any reason to criticize the twelfth dose.