The problem is that there are not enough vaccines to inoculate everyone. We are in to the 5th month of vaccination, and only around 925 million doses of the vaccine has been administered so far. In order to vaccinate everyone, we need around 15 billion doses. So even by the end of this year, only a small minority of the world population will be vaccinated against COVID 19. And worse still, those who got completely vaccinated (with two doses of the vaccine) may need another booster dose after 12 months.