How long after getting my initial COVID-19 vaccines
can I get an additional dose?
CDC recommends the additional dose of an mRNA COVID-19 vaccine be administered at least four weeks (28 days) after a second dose of Pfizer-BioNTech COVID-19 vaccine or Moderna COVID-19 vaccine.
Can you mix and match the vaccines?
For people who received either Pfizer-BioNTech or Moderna’s COVID-19 vaccine series, a third dose of the same mRNA vaccine should be used. A person should not receive more than three mRNA vaccine doses.
What should immunocompromised people who
received the J&J/Janssen vaccine do?
The FDA’s recent EUA amendment only applies to mRNA COVID-19 vaccines (Moderna and Pfizer), as does CDC’s recommendation.
What are the risks of vaccinating individuals
with an additional dose?
There is limited information about the risks of receiving an additional dose of vaccine, and the safety, efficacy, and benefit of additional doses of COVID-19 vaccine in immunocompromised people continues to be evaluated. So far, reactions reported after the third mRNA dose were similar to that of the two-dose series: fatigue and pain at injection site were the most commonly reported side effects, and overall, most symptoms were mild to moderate.
However, as with the two-dose series, serious side effects are rare, but may occur.
To view the IDPH Frequently Asked Questions on 3rd dose vaccines for COVID-19, visit: