Both vaccines are known to prevent disease with a high efficacy rate of up to 95% in phase 3 trials. To put this in perspective, the efficacy is almost as good as the measles vaccine, which is historically known to be the most effective vaccine.

Both Pfizer and Moderna vaccines are equally efficacious and safe. Pfizer has more stringent storage requirements (-70°C/-94°F) but that should not be a reason for not offering the vaccine.