General guidance is to avoid mixing-and-matching 2-dose COVID-19 vaccines

A D.C.-area woman who told WTOP she got two different COVID-19 vaccines called the newsroom upset, and wondering how important it is that both doses match. The general consensus is that they should — if possible.

The consensus in the scientific community is that there hasn’t been enough time to properly study the effects of mixing and matching separate vaccines, so it is best avoided if possible.

The Centers for Disease Control and Prevention current guidance states:

COVID-19 vaccines are not interchangeable. The safety and efficacy of a mixed-product series have not been evaluated. Both doses of the series should be completed with the same product.

The Maryland Department of Health follows CDC guidelines.

In exceptional situations in which the vaccine product given for the first dose cannot be determined or is no longer available, any available mRNA COVID-19 vaccine may be administered at a minimum interval of 28 days between doses to complete the mRNA COVID-19 vaccination series. In situations where the same mRNA vaccine product is temporarily unavailable, it is preferable to delay the second dose (up to six weeks) to receive the same product than to receive a mixed series using a different product.

The Virginia Department of Health said studies on the subject are ongoing.

Studies to answer this question are being done now.

For the moment, because there is currently no information about how well you are protected from COVID-19 if you get one dose of each company’s vaccine instead of two, the CDC strongly recommends that the vaccine series should be completed with a second dose of the same company’s vaccine.

However, if, because of unavoidable circumstances, doses of two different COVID-19 mRNA vaccines have been given, no additional doses of either vaccine are recommended.

If you have a contraindication to getting the second mRNA COVID-19 vaccine dose, you may be able to get the Johnson & Johnson vaccine. This is a discussion that should be had with your healthcare provider.

D.C.’s Department of Health states:

It is important to get both doses of the same vaccine and not to mix-and-match, or the vaccine might not work as well.

Regional health system Kaiser Permanente, which is contracted to help vaccinate, among others, members of Prince George’s County Schools, states:

For 2-shot vaccines, the same vaccine brand needs to be used for both shots.

The United Kingdom currently has studies underway to evaluate the mix-and-matching of COVID-19 vaccines. It addresses the issue in guidance released in February, specifically related to how to handle second doses being interrupted or delayed — stating on page 13, in part:

There is no evidence on the interchangeability of the COVID-19 vaccines although studies are underway. Therefore, every effort should be made to determine which vaccine the individual received and to complete with the same vaccine. For individuals who started the schedule and who attend for vaccination at a site where the same vaccine is not available, or if the first product received is unknown, it is reasonable to offer one dose of the locally available product to complete the schedule.

More Coronavirus News

Looking for more information? D.C., Maryland and Virginia are each releasing more data every day. Visit their official sites here: Virginia | Maryland | D.C.

Kristi King

Kristi King is a veteran reporter who has been working in the WTOP newsroom since 1990. She covers everything from breaking news to consumer concerns and the latest medical developments.

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