Both vaccines have a very high level of effectiveness: Pfizer has a 95 percent rate and Moderna has a 94 percent rate. To be effective, both vaccines require two shots, given a few weeks apart. Vaccines cannot be mixed and matched between doses. The length of vaccine-induced immunity is not known at this time, and booster shots may be required.
Some people who get a COVID-19 vaccine will experience side effects, particularly after a second dose. The side effects of the vaccine appear to be minor and temporary, including injection site pain, fatigue, and occasional fever, headache, or aching muscles and joints. These side effects fade within 1-2 days; no long-term effects have been detected thus far.
While the vaccine provides significant protection, it is not 100% effective. There is a slight chance that vaccinated individuals can still get infected with a mild case of the virus. Those who have taken the vaccine can also still spread the virus to others at home and at work. Thus it is critical that everyone continue to wear PPE and follow public health protocols for the foreseeable future.