Because 99.9% isn't the case for every group. Most people that are concerned about the virus are worried about other people that have a higher risk of mortality from it. Same thing goes for the flu, measles, etc. Children and the elderly are most at risk for the flu and children for measles so vaccines help prevent those deaths. It's important for at-risk people to get the vaccine, but their odds of being helped are increased if other groups of people get it too. I'm not sure what is planned, but hopefully insurance covers the vaccine for a lot of the general public.