Worst case scenario: We have a lot of highly infectious but asymptomatic people walking around, not wearing masks, mingling in crowds, visiting grandma, and infecting people who haven’t been able to be vaccinated or for whom the vaccine isn’t effective, and making them sick.
Infection also comes from physically coming into contact with the virus, on your clothes or your skin, and in such a case it is easy to literally carry it to someone else. Being vaccinated merely means that you don’t fall ill yourself.
As has been said here and elsewhere, we won’t know yet whether a vaccinated person can transfer the virus by the airborne aerosol route, so it would be advisable to keep wearing those masks for a while. Once a large number of people have become immune, either from vaccination or recovery from a bout of COVID, the numbers should start falling quickly. I wish I knew when that will be.
I suggest you read the thread rather than just repeating this false assertion. And more information countering this false claim in this thread:
Vaccine: you'll get COVID but no symptoms? - #28 by Tfletch1
When they say a vaccine is 95% effective have they published who this was tested on? It appears about 90% don’t get all that sick anyway. Would the vaccine be 90% effective if the test were run on 80 year olds?
The data published so far seems to show a fairly consistent effectiveness across ages, which is somewhat surprising good news.
The test subjects are divided into two groups, vaccinated and placebo. They carry on with their lives, and we wait until enough people get sick that there’s enough statistical power to be confident in the results. 95% efficacy means that for every 20 people who got COVID in the placebo group, just 1 got sick in the vaccinated group.