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Advanced Neurology Neurological adverse events post-vaccination

AEs—contrary to the conclusion of a recently published Relative proportions could be compared with detailed
systematic review. The authors found significantly more AE tracking in large clinical trials to detect possible
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neurological AEs reported following Janssen (AD26. perturbations in the VAERS database such that as the
CoV2.S) vaccination when compared to either Pfizer– timeframe widens post-immunization, the fraction of
BioNTech (BNT162b2) or Moderna (mRNA-1273) AEs reported decreases. For example, a clinical study to
vaccination; however, their calculations do not include the reveal differences in reporting bias could be conducted
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X
reporting bias ( r ) term. Influenza vaccinees have higher by comparing two matched populations by tracking
i
normalized frequencies for ages of 0 – 9 years compared to VAERS reports: Group A based on the current VAERS
older ages for abnormal behavior, aphasia, coordination reporting while group B based on the reporting of all
abnormal, seizure, and speech disorder (Tables S2 and S3); AEs. Adverse events for group A would be tracked (as
therefore, the risk of neurological AEs may decrease with done currently) and all AEs are collected for group B.
increasing child age. In the case of the COVID-19 products, These results could then be compared to larger clinical
the normalized frequencies for mental status changes were studies using adjustments for asymptomatic individuals
found to increase when compared to influenza for adults and the tracking details of AEs. For each specific AE,
older than 60 (Tables S2 and S3), with upward trends for reporting biases would be the same for all vaccines to
older adults with multiple AEs reported for both vaccines. enable quantitative comparisons.
The etiology for these observations remains unknown and
there could be other contributing factors, including lower 5. Conclusion
resiliency associated with aging and unknown effects of
repeat “boosting” with COVID-19-modified mRNA and The risks associated with developing neurological AEs
adenoviral platforms. A retrospective cohort study of older following vaccinations might be reduced through the
adults in the United States found a low risk for AEs in the following measures: (i) Modifying the current vaccination
context of the modified mRNA products while noting that schedule recommendations for infants, (ii) reducing the
the risk of all AEs increased with greater frailty. In the case number of concomitant vaccinations, (iii) evaluation and
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of tinnitus, COVID-19 vaccines have the highest normalized removal of possible contaminants from the manufacturing
frequency (Table S1). COVID-19 vaccine-associated process, (iv) modifying or removing vaccine excipients
tinnitus has been documented and the observed (e.g., replacing aluminum-containing adjuvant with
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immediate onset of tinnitus (within 24 h of vaccination) an alternative adjuvant), and (v) modifying vaccine
may not be consistent with the proposed possible components (the AE profiles for closely related vaccines for
mechanisms of molecular mimicry and autoimmune the same target organism can have different AE profiles).
reactions or antibody-antigen complexes leading to type III Relevant documents (e.g., FDA package insert) should be
hypersensitivity reaction. COVID-19 vaccines have been adjusted as appropriate to ensure that informed consent
suggested to act as a trigger event for serious neurological requirements are met.
AEs following immunization. 58
Acknowledgments
4.3. Comparing normalized frequencies
None.
Examining AEs by age across all vaccines enables the
identification of safety signals (Table 1). Comparing and Funding
contrasting normalized frequencies between equivalent None.
vaccines can better inform consent and future dosing
recommendations. Examining yearly normalized frequencies Conflict of interest
can illuminate impacts of changes to excipient compositions
and manufacturing quality improvements. The author declares they have no competing interests.

4.4. Study limitations Author contributions
This study is based on AEs reported to the VAERS database. Conceptualization: Darrell O. Ricke
Only a small subset of AEs experienced by vaccines was Investigation: Darrell O. Ricke
reported to VAERS due to under-reporting. This study Methodology: Darrell O. Ricke
infers that AEs within VAERS proportionally reflect Formal analysis: Darrell O. Ricke
those experienced by vaccinees. Exclusion of reported Visualization: Darrell O. Ricke
AEs or reporting biases would potentially prevent VAERS Writing – original draft: Darrell O. Ricke
from representing the immunized populations accurately. Writing – review & editing: Darrell O. Ricke, Jessica Rose

Volume 3 Issue 1 (2024) 8 https://doi.org/10.36922/an.2258