Will your COVID-19 vaccine be less effective if you need to wait longer for a second dose? – cleveland.com

CLEVELAND, Ohio The U.S. rollout of the COVID-19 vaccine has been rocky, hindered by a lack of supply and shipping delays.

What happens if those delays cause a delay for someone who is waiting for a second dose of the vaccine?

Our readers have questions about the coronavirus vaccine, and cleveland.com is getting answers from health care experts.

Q: If coronavirus vaccine shipments are delayed and you need to wait longer for a second dose, will it be less effective?

Both coronavirus vaccines approved by the U.S. require two doses spaced out over several weeks. The Pfizer/BioNTech vaccine doses should be given at least 21 days apart, and the Moderna vaccine doses should be given at least 28 days apart.

The U.S. Centers for Disease Control and Prevention recommends getting the second dose as close to those schedule as possible. After you wait the required 21 or 28 days, there is no maximum interval between the two doses.

There is a minimum to wait, said Dr. David Margolius, MetroHealths division director of internal medicine. But youre OK delaying the booster.

In fact, Margolius said MetroHealth is delaying the second dose by design. The Pfizer vaccine in particular is more likely to cause side effects like pain, tiredness and fever after the second dose, according to the U.S. Food and Drug Administration. MetroHealth is scheduling the second dose on Fridays to avoid side effects during the work week, Margolius said.

However, health care experts recommend getting the second dose as close to the 21- or 28-day schedule as possible. The vaccines were approved based on data from clinical trials, and those clinical trials did not consider the effects of a significant delay, said Dr. Shanu Agarwal, an infectious disease physician at Summa Akron City Hospital.

If its something thats out of your control and they dont have it available, just get it as soon as they do, Agarwal said.

Some countries have opted to delay the second dose of the vaccine in order to give the first dose to a greater number of people. Last month, the U.K. announced that it planned to give doses of the Pfizer vaccine 12 weeks apart, four times longer than Pfizer has recommended.

The FDA said earlier this month that it has been following those types of discussions but does not recommend altering the vaccine schedule. There is no data to support changing the vaccine schedule, the FDA said in a news release.

Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk, undermining the historic vaccination efforts to protect the population from COVID-19, the FDA said in the news release.

Do you have questions about the COVID-19 vaccine that youd like an expert to answer? Send it in a brief email to cleveland.com reporter Evan MacDonald at emacdonald@cleveland.com.

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Will your COVID-19 vaccine be less effective if you need to wait longer for a second dose? - cleveland.com