Using Los Angeles County as their subject, CSUN geography professor Steven Graves and geography graduate student Petra Nichols constructed a series of statistical models that demonstrate that certain neighborhood housing characteristics — including income and ethnicity — made some communities more vulnerable to the virus than others. Image credit, wildpixel, iStock.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) issued a joint statement Jan. 13 regarding a possible link between Pfizer’s COVID-19 booster shot to an increased risk of stroke for seniors. Nonetheless, the two agencies recommend that everyone stay up-to-date on their vaccinations.

Through the CDC’s Vaccine Safety Datalink (VSD), a near real-time surveillance system, the agency met the “statistical criteria” to investigate whether there was a higher risk of ischemic stroke in seniors ages 65 and over who received the updated Pfizer COVID-19 booster vaccine. Those who had were more likely to have a stroke within 21 days following their vaccination compared to 22-42 days after their shot.

A CDC spokesperson said that, among the 550,000 seniors who received the booster, the VSD system found 130 people who had a stroke. No deaths have been reported.

“All [safety] signals require further investigation and confirmation from formal epidemiologic studies,” the statement read. “When one system detects a signal, the other safety monitoring systems are checked to validate whether the signal represents an actual concern with the vaccine or if it can be determined to be of no clinical relevance.”

The CDC has not found a similar link between Moderna’s updated booster vaccine and an increased risk of stroke.

Furthermore, no other databases or systems — including the Centers for Medicare and Medicaid Services database and the Vaccine Adverse Event Reporting System (VAERS) — have found any indication for an increased risk of strokes from the Pfizer vaccine.

The CDC and FDA still recommend that everyone ages 6 months and over get vaccinated against COVID-19. The California Department of Public Health issued a statement on Jan. 15, agreeing with their recommendation.

“California continues to support its vaccine recommendations and encourage Californians to stay up-to-date with their vaccines,” the statement read. “Vaccines continue to be safe and effective, and they remain the most powerful weapon against hospitalization and serious illness due to COVID-19. Widespread vaccination is a major reason California is in a position to wind down emergency processes.”

The CDC and FDA are continuing to evaluate additional data from the numerous vaccine safety systems. The data and analyses will be discussed in the FDA’s Vaccines and Related Biological Products Advisory Committee on Jan. 26.