In general, there are several factors to keep in mind:
- Two doses of the Pfizer-BioNTech, Moderna COVID-19, Oxford-AstraZeneca vaccine, Sinopharm, and Sinovac vaccines are recommended to achieve strong and lasting protection, while only one dose is needed for Janssen (Johnson & Johnson) vaccine.
- After receiving the first dose, it takes time for your body to develop protection. So, you can be infected with the virus in the days following vaccination before the vaccine has begun to provide protection.
- Or, you can be infected with the virus without knowing it in the days before you are vaccinated.
- The second dose (except for Janssen (Johnson & Johnson) vaccine which only needs one dose) is also important to help you build the strongest possible defense against developing COVID-19 disease, a more intense but also more mature immune response.
- Vaccination provides protection from COVID-19 disease. However, vaccination may not prevent you from becoming infected with the virus without any symptoms and then transmitting the virus on to others.
For all these reasons, until this pandemic is over it is very important that everyone who gets vaccinated still continues to take precautions like physical distancing, using a mask, cleaning hands and avoiding crowded places.
- are not 100% effective
- cannot prevent disease from prior infection
- are not effective immediately
- may require two doses for optimal protection