This is not unheard of. Here’s why it can happen. First, remember the vaccine itself cannot cause covid-19. A person may, however, be exposed to covid-19 just before getting vaccinated and become infected. Also, full protection from the vaccine does not occur until about 2 weeks after the second dose. People who have received only the first dose are not yet fully protected and could be susceptible to infection.
Additionally, breakthrough cases – when a vaccinated person is infected – can happen as no vaccine is a 100% effective. Breakthrough cases are more common than before due to the highly transmissible omicron variant. To help protect yourself from severe disease and death, experts recommend that you fully vaccinate and get the booster shot.