812 and 17 cases of CVA were reported after COVID-19 vaccination and all other vaccinations, respectively, during the COVID-19 vaccination period.

The reporting rate of CVA after COVID-19 vaccination was significantly higher than the rate after all other vaccines (4.2 vs 0.07 per million p<0.00001).  However, it was within the incidence range expected in the general population. Only 2 cases of CVA were reported after vaccination during the pandemic period and no cases outside the pandemic period.

Based upon self-controlled and case-centered analyses, there is a significant difference in the reporting rate of CVA after COVID vaccination between the risk period (six weeks after vaccination was defined as the risk period of probable association) and control period (93.97% vs 1.97-2.96% p< 0.0001).

The reporting rate of CVA after Pfizer was significantly higher compared to CVA after Moderna and Johnson and Johnson vaccinations (5.9 vs 2.8 vs 3.2 per million p<0.0001).  However, all reporting rates were within the expected incidence range reported in the general population.

There is no association between CVA and COVID-19 vaccination. Furthermore, this work is based on passive surveillance where several limitations exist, which include under-reporting, differential reporting and nonreported or undiagnosed concomitant COVID-19 infection. These factors preclude establishing a cause-effect relationship. Controlled studies are needed for further investigation.