If a vaccine is say 90% effective it is expected that 90% will have no symptoms of covid 19 .The other 10% may have symptoms if exposed to covid 19.. Also you may have symptoms if there hasnt been enough time for your body to make antibodies.
Bottom line:Read the comments at the bottom in the article that Walt posted above.
Yesterday it was reported that Israeli medical-types have discovered that the S. African mutation of C-19 isn't affected by the Pfizer vaccine. No mention was made regarding the other vaccines' efficacy against it one way or the other though as I recall.And so we have vaccines that are not 100% effective. As the article here and another I read said that the patients were not severely ill and full recovery was expected..
Don’t use this as any sort of leverage to prop up the anti-vaxer’s case... We will not achieve herd immunity unless we have a much higher vaccination rate (I believe I read 80+ percent)...