I think most people consider 91% to be “truly” protective. Nothing is 100%. The vaccine is more than effective enough to reduce the risk of Covid to the general background risk level of life in general (things like car accidents, slipping in the shower, eating red meat, contracting a flesh eating amoeba from swimming in a lake etc.)
It's quite clear that the person who wrote the comment I'm replying to believes that "truly protective" means 100% protection, and that if the vaccine was "truly protective" you no longer need to worry about getting COVID.
This is a very dangerous idea and why there is so much confusion and misinformation.
By insisting that 91% is "truly effective" in conversations like this you are not helping.
Not to be condescending, but because people have been saying for a year now or more now that the virus will rapidly evolve and any vaccines will become less effective over time because of it.
And the virus rapidly evolved and the vaccines we have became less effective to new strains, as expected. A quick deployment of vaccines would greatly reduce that risk (see: Japan currently having infections in the double digits following a rapid deployment in vaccines and universal masks, leaving little room for new strains to adapt).
The pandemic has been a long chain of some insightful people saying "This bad thing will happen if people don't take X precaution." People say that's a lie--then don't take X precautions. Bad thing happens. People get angry and say they were lied to because bad thing happened when they were told it wouldn't happen (because loads of people took no precautions). Then there's a warning about another bad thing happening, followed by denial.
The Pfizer/BioNTech vaccine has an effectiveness of about 91%. That means in about 9% of cases it is not protective.
I'm amazed we are this deep into this pandemic and people still have black and white thinking wrt to vaccinces.