People are considered fully vaccinated two weeks after their second dose of the Pfizer-BioNTech or Moderna COVID-19 vaccines, or two weeks after the single-dose Johnson & Johnson’s Janssen COVID-19 vaccine. According to the CDC, if you received Pfizer-BioNTech or Moderna initial vaccinations more than six months ago, you should get a booster if you are ages 50 years or older or ages 18 and older and live in a long-term care setting. For those who received the Johnson & Johnson COVID-19 vaccine, booster shots are also recommended for those who are 18 and older and who were vaccinated two or more months ago.