About 2,300 doses of the Johnson & Johnson vaccine won't get into arms in Fresno County this week after the public health department followed CDC and FDA recommendations to pause for a review.
Out of almost 7 million doses administered in the United States, six women between the ages of 18 and 48 developed blood clots known as cerebral venous sinus thrombosis, or CVST.
None of them were in California and Fresno County health officer Dr. Rais Vohra says the 40,659 Central Valley residents who got the vaccine shouldn't lose any sleep.
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"I don't think people have anything to worry about if they're not feeling any symptoms," he said.
Dr. Vohra says the signs of trouble would be persistent headaches or abdominal pain more than two days after vaccination.
The Central Valley hasn't relied very much on Johnson & Johnson for its vaccine supply.
So far, it accounts for a total of 4.2% of all vaccinations in Fresno, Kings, Tulare, Merced, Mariposa, and Madera counties.
The reports of blood clots are extremely rare.
Fresno State microbiologist Dr. Tricia Van Laar says the clots are actually more common in the general population than in the vaccinated population.
"According to Johns Hopkins, this type of blood clot, the CVST, is normally found in the population at a rate of 5 in a million," said the Fresno state microbiologist.
She says nonsteroidal anti-inflammatory drugs such as Advil and Aleve are linked to rare blood clots. Birth control pills are too.
So researchers will have to check whether the reported blood clots are linked to a vaccine or something else.
Both she and Dr. Vohra say this pause -- like the Moderna pause in January -- shows scientists taking their time to get things right, so they hope people won't hesitate to get vaccinated.
"COVID is still out there," said Dr. Vohra. "It's still, unfortunately, claiming lives and putting people in the hospital. And one of our best defenses against COVID is getting vaccinated and so getting the vaccine is definitely the right step to take even in light of this development."
The next move for Central Valley public health officials will be determined by an FDA review, which is expected to last just a few days while they figure out exactly what's going on with the Johnson & Johnson vaccine.