No, it means it DOESNT stop 50% of infections. If you vaccinated everyone, as you suggested, the virus would have plenty of places to do, as you suggested it wouldnt.
Actually it does
In a laymans explanation.
The virus doesn;t just need 'plenty of places to do". The virus needs opportunity to infect.
Studies show that when people who were infectious went home to family. Who they were quarantined with. No vaccinations, no masking, no social distancing. Living in close quarters with and infectious person. Basically the worst case scenario for spreading respiratory infection. The rate of transmission was only 27%. That means in the worst case.. the virus only had about a 27%chance of infecting another person in the household.
So your chance of getting infection from someone at the grocery store? Pretty dang low.
Thats without ANY intervention.
So.. when you add in EVERYONE (including school age children ) vaccination. The likelihood of getting infected drops considerable
Add in rigorous testing.. so people that are infectious have to quarantine,
Add in masking?
Add in social distancing.
Add in immunity from prior infection
The opportunity to infect people drops to a point that over time..the virus has simply no opportunity to propogate enough to stay viable.
Take a look at the flu during the pandemdic. Everyone asked.. "where is the flu"... Flu numbers were dramatically low. And why? The flu vaccines are about as effective as the covid vaccines if not a little less.
But we had social distancing, masking, and a higher than normal level of vaccination that year.
Yes.. if we got everyone vaccinated and were willing for a period of time to mask, social distance, and test? We could get rid of covid.
The chances are less now because the variants are more infectious.. but even now... it could be possible. But covid has become a political issue..and therefore getting compliance is not likely.