No apparent link between COVID-19 vax and cerebrovascular outcomes

Several studies presented at AAN 2022 have revealed a lack of association between COVID-19 vaccination and negative cerebrovascular outcomes.

The studies were conducted using the Vaccine Adverse Event Reporting System (VAERS). In the first study, the researchers compared reports of cerebrovascular accidents (CVAs) after COVID-19 vaccinations to those of CVAs following three different periods for other vaccinations – pre–COVID-19 period (January–August 2019), pre–COVID-19 vaccination period (April–November 2020), and COVID-19 vaccination period (December 2020–July 2021).

During the COVID-19 vaccination period, 812 cases of CVAs were reported after receipt of COVID-19 vaccination, while 17 cases were reported after other vaccinations.

There was a higher rate of CVA reports following COVID-19 vaccination than other vaccinations (4.2 vs 0.07 per million; p<0.00001). [AAN 2022, abstract S18.002]

The rates of CVA were higher after receipt of the Pfizer compared with the Moderna or Johnson and Johnson vaccines (5.9, 2.8, and 3.2 per million, respectively; p<0.0001). 

Despite these findings, the rates were within the incidence range expected in the general population, the researchers said.

Two cases of post-vaccination CVA were reported within the pandemic period and none outside the pandemic period.

Post–COVID-19 vaccination CVA reporting rate was different between the risk period of probable association (6 weeks after vaccination) and control period (93.97 percent vs 1.97–2.96 percent; p<0.0001).

“CVAs have been reported in severe COVID-19 infections and are attributed to infection-related hypercoagulability and inflammation,” said the researchers.

“There is no association between CVA and COVID-19 vaccination … “[However, certain limitations] preclude establishing a cause-effect relationship,” they continued, calling for further research into assessing these outcomes.

Any association with rhabdomyolysis?

Another study, also using the VAERS dataset, suggested a potential association between receipt of the COVID-19 vaccine and rhabdomyolysis despite a lack of significant increase in cases post-vaccination.

Eight cases of rhabdomyolysis were reported following other vaccinations and 169 following COVID-19 vaccinations. During the COVID-19 vaccination period, the rate of rhabdomyolysis after COVID-19 vaccination was elevated compared with after all other vaccinations (8.75 vs 0.34 per 10 million; p<0.0001). [AAN 2022, abstract S18.006]

Similar to that with CVAs, the rates were within the incidence range expected in the general population.

Four cases of post-vaccination rhabdomyolysis were reported during the pre–COVID-19 vaccination period and eight during the pre–COVID-19 period.

The rates of rhabdomyolysis after COVID-19 vaccination were higher during the risk than control periods (98.22 percent vs 0.06 percent; p<0.0001), though there was no significant difference in rates between the three vaccines.

“There is no significant increase in cases of rhabdomyolysis with COVID-19 vaccinations. However, the unbalanced distribution of rhabdomyolysis within the first 12 weeks, with a significant increase in reporting rate, suggests that some rhabdomyolysis cases are temporally associated with COVID-19 vaccination,” the researchers noted.

“This supports an autoimmune-mediated muscle injury mechanism rather than direct viral muscle invasion for cases of rhabdomyolysis occurring after COVID-19 infections,” they added.

The researchers acknowledged the inability to rule out undiagnosed or unreported cases of COVID-19 in this data set.