Vaccine effectiveness questioned with delayed second doses in Madera County

FRESNO, Calif. (KFSN) -- Some people in Madera County are upset about the county's system of scheduling second doses of the COVID-19 vaccines.

Second doses of the Moderna and Pfizer COVID-19 vaccines are tickets to the most protection we can get from the virus.

They act as boosters and bring the vaccines' effectiveness up above 90%.

For Moderna, the wait is supposed to be 28 days after the first dose.

For Pfizer, it's 21 days.

But Action News got complaints from people in Madera County that the county wouldn't let them schedule second doses of Pfizer any sooner than 28 days after the first dose.

The public health department got similar questions.

"Why is Madera County Department of Public Health scheduling the Pfizer doses 28 days apart rather than the recommended 21?" was one question county public health director Sara Bosse read during a recent Facebook Q&A session with Dr. Simon Paul, the county health officer. "Is there research showing the vaccine will be just as effective if administered that way?"

"The recommendation is 21 days or longer," said Dr. Paul.

He says the first shot needs some time to build up your immune system's response before you get a booster shot.

"Three weeks is about the earliest you can boost," said Dr. Paul. "If you give a second dose four weeks, five weeks, six weeks later, it will definitely work as well or better than doing it at an earlier time point."

Guidance from the Centers for Disease Control says to separate doses by at least 21 days, and preferably get the second within six weeks.

But in smaller print, it says to administer the second dose as close as possible to the recommended interval of 21 days.

A few patients in Pfizer's clinical trial got their second doses beyond the 21-day window, but the number was small, and the company's CEO says there's not enough data on delayed second doses to definitively speak to the impact.

Dr. Paul says Madera County is hitting close enough to the mark to make sure the vaccines offer maximum protection, even while the county juggles supply and remote delivery issues.

"We're trying to get people in on week 3, 4, or 5," he said. "So if you aim for 28 days, you get people a bit earlier, some people a bit later."

Bosse tells Action News Madera County patients should be able to scheduled both doses at once, and their second doses of Pfizer at exactly 21 days, as soon as the county joins the state's MyTurn signup system.

They don't know when that'll happen, though, because MyTurn doesn't have all the functionality the county needs.
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