Question: I am receiving conflicting information on the spacing between vaccines and would like to know what is considered the best practice.  I received my flu vaccine (senior dosage) on Thursday 9/9 at my doctor’s office.  I had my first shingrix vaccine back in May and wanted to get my second one on Saturday, the 11th, but the tech in the Walgreens pharmacy said I would need to wait 14 days before getting the vaccine, because it would interfere with the production of antibodies from my flu shot.  Today, I went to CVS to get my covid booster shot and was told that I absolutely have to wait 4 weeks, not just 14 days, between vaccines unless I am getting them at the same time.  This is very confusing. Why is it okay to get them at the same time, but not 3 days apart? Or is it okay to get them at the same time?

Answer: What a confusing experience you’ve had!  As always, please consult your doctor.  And in the meantime, based on recommendations from CDC, I do not see any reason that you need to wait.  Specifically, per CDC’s Interim Clinical Considerations for Use of COVID-19 Vaccines (August 31, 2021 update), “COVID-19 vaccines may now be administered without regard to timing of other vaccines.”  This means that the booster can be given at the same time as other vaccines and that a booster need not be deferred for some amount of time after receipt of a different type of vaccine (like the shingles vaccine).  Of course, there is a waiting period between the COVID-19 booster and the completion of the initial 2-dose Moderna/Pfizer series; the booster should be given at least 28 days after the completion series.  Turning to the shingles vaccine, Shingrix, I was curious if there were any specific guidelines related to coadministration of other vaccines with it.  Here too, CDC recommends that it can be administered at the same time as other vaccines and gives no recommendation about a waiting period post influenza vaccination (or other vaccination).

Why the confusion?  For the COVID vaccine, I think the confusion stems from older CDC guidance, which did require a minimum 14-day interval between COVID vaccination and administration of other vaccines.  This was a recommendation made out of an abundance of caution when the COVID vaccines were new, and was changed as a result of substantial safety data collected in the intervening months.  As to the 4 weeks bit you describe, my only supposition is a conflation of the guidelines about booster receipt at least 4 weeks after the 2nd COVID vaccine dose.

*Note to readers: boosters are currently recommended only for moderate to severely immunocompromised people.