The Pfizer/BioNTech COVID-19 vaccine teaches the immune system to identify the virus and destroys it.
The Pfizer/BioNTech vaccine is made from nucleoside-modified mRNA. The mRNA helps the immune system to recognize the SARS-CoV-2 virus. Once an individual is administered with this vaccine, their body makes copies of the spike protein, which helps teach the immune system to react defensively by triggering an immune response against COVID-19.
Thus, the vaccine does not provide immunity or lessen it. Instead, it teaches the body's immune system to recognize the virus and defeat it.
The COVID-19 pandemic has given rise to a lot of potentially dangerous misinformation. For reliable advice on COVID-19 including symptoms, prevention and available treatment, please refer to the World Health Organisation or your national healthcare authority.