I'm no doctor or virologist so I can't state for sure how vaccines work but I do tend to lean towards your statement that they only prevent you from dying, but little protection from being infected. Maybe they lessen the symptoms, I'm not sure?
My previous point was that the Thai government is counting on at least 70% of the population being vaccinated as their requirement to open up all of Thailand to tourists. They feel that this will be effective for controlling the virus. Phuket, in my mind, seems to have been used as the guinea pig to test their theory. So if Phuket was their 70% test, what have they learned? People are still getting infected by the virus (over 200 a day) and people are dying from the virus. Do they have any statistics to share with us on which vaccines were used and did these vaccines live up to their expectations. Did the vaccines lessen the symptoms for those that were infected. Were any of the people who died previously vaccinated and if so which vaccines worked the best and which ones failed?
There seem to be several studies around the world done on the efficacies of vaccines but here right in our own backyard, we have the Phuket sandbox study that could give us answers.