Page 96 - AN-3-1

Advanced Neurology Neurological adverse events post-vaccination

can be lost against background frequencies of AEs as 2.2. Adverse events following immunization
the number of days considered increases. The observed Adverse events following immunization can be represented
highest reports of neurological AEs on day 0 may by the following equation for a population subset
simply reflect reporting bias. The observed frequencies immunized (P), AE (X), (n) days, reporting bias ( r ) for
X
i
of AEs for each vaccine should represent background the i day post-immunization, vaccine-associated AEs
th
frequencies with expected random variations. Higher reported on the i day post-immunization (v ), and daily
X
th
associated frequencies of AEs likely represent potential X i
safety signals worthy of further investigations such background rate of AE (b ) (Equation I).
as proportional reporting ratio, Bayesian, or causality n days
X
( )= P*
r
assessments. Performing surveillance on VAERS can Adverse event X [ Σ i X ( * v + b X ) ] (I)
i
help discover safety signals not detected in pre-market i=0
testing that warrant further investigations. Therefore, Day 0 (the first 24 h) following immunization can be
in this study, neurological AEs within VAERS were examined to solve for the term X (Equation II):
examined retrospectively. Neurological AEs reported v 0
X
X
following immunization were compared across multiple Adverse event ( withinX 24 h )= AE = P* r * (v +b X )
X
0
0
0
vaccines. Normalized neurological AE frequencies,
both by the age group and also by onset within 24 h of (II)
immunization, were examined. Findings from this study Immunization-associated AEs (X) are detectable when
can help formulate strategies to reduce reporting bias v X > 0 (when the number of AEs exceeds the background
0
and background events. rate within 24 h of immunization).
2. Materials and methods When there is no immunization-associated AE (X), the
number of AEs is the background AEs (Equation III).
2.1. Materials
Background adverse events
The VAERS database was retrospectively examined for X X X
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the neurological AEs designated by the following Medical ( within 24X h )= AE = P* r * b (III)
0
0
Dictionary for Regulatory Activities (MedDRA) codes: The VAERS reports represent only a subset of the
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Abnormal behavior, antisocial behavior, aphasia, autism or population vaccinated with one or more symptoms
ASD (combined), cognitive disorder, convulsion or seizure a
(combined), coordination abnormal, delirium, depression, ( P 1+ symptoms ) with the true population size for a vaccine
encephalopathy, encephalitis, febrile convulsion, meningitis, represented in Equation IV.
mental disorder, mental impairment, mental status changes, Population size (P) for vaccine (a):
metabolic encephalopathy, nervous system disorder,
a
a
a
neurodevelopmental disorder, psychomotor hyperactivity, P = P 1+ symptoms + P No symptoms (IV)
speech disorder, staring, and tinnitus. Within the VAERS Comparisons between different vaccines (a and b) for
data records, usage of “convulsion” was transitioned to the same AE are represented by Equation V.
“seizure,” and “autism” to “ASD.” Syncope was also included
for comparisons with seizure. The downloaded VAERS data Adverse events comparison between vaccines
includes all AEs reported from 1990 to November 3, 2023. P * r X ( * v a:X +b X )
a
The Ruby program named vaers_slice4.rb was used to tally (a,b : X within 24 h )= 1+ 0 0 (V)

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b
selected reported vaccine AEs by vaccine, day of onset, year, P * r 0 X ( * v b:X +b X )
1+
0
and age. The vaers_slice4.rb program takes a list of one or more
a
b
AE names as input, and characterizing them with the VAERS Note that when P>>P , the ratios between multiple AEs (X,
1
1
+
+
data files. The output from vaers_slice4.rb consists of multiple
a
b
reports: summaries by vaccine, summary by year, summaries Y, Z, etc.) will appear similar reflecting the ratio P / P . In
1+
1+
by vaccine age, summaries by day of onset of symptoms by general, when a:X b:X a:X b:X
(i) dose and sex and (ii) vaccine type, and two summaries of AE 0 >> AE 0 , then v 0 >> v 0 .
additional symptoms reported (selected symptoms and all 3. Results
other symptoms). The output from vaers_matrix.rb consists
of multiple reports: summary by vaccine and dose, summary 3.1. Day 0 onset safety signals
by vaccine and year, summary by vaccine and AEs, summary The VAERS database was data mined with vaers_slice4.
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by vaccine and day of onset, and summary by vaccine and age. rb for selected neurological AEs and vaers_matrix.
Volume 3 Issue 1 (2024) 3 https://doi.org/10.36922/an.2258