Safety and efficiency of COVID-19 vaccine in North Africa

Abstract

Background In the absence of a specific treatment for COVID-19, preventive measures have been implemented to control this pandemic and vaccination is one of them. However, it is crucial to verify the safety and efficiency of every vaccine. The aim was to determinate the predictive factors of side effects and reinfection after COVID-19 vaccine. Methods A cross-sectional study was conducted in February 2022 among Tunisians infected with COVID-19 between March 2020 and February 2022, using an online self-administered questionnaire. We conducted univariate and multivariate analyses using binary stepwise logistic regression. Results A total of 1541 was selected from 1911 individuals. Comorbidities affected a quarter of the population (22.3%). Before the initial infection, 39.3% had received full vaccination, and 8.7% had received partial vaccination. By February 2022, the majority (82.9%) had received at least two vaccine doses. The reinfection rate was 30.6%. All vaccines prior to the first infection was identified as a protective factor against reinfection. Inactivated virus vaccinations were less likely to induce adverse effects. Conclusion ach vaccine has its own set of advantages and disadvantages: mRNA-based vaccines had a higher incidence of side effects but all vaccines provided better protection against reinfection.

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RESEARCH ARTICLE
Safety and eciency of COVID-19 vaccine in North Africa
Souhir Chelly, Shayma Jaziri, Asma Ammar, Olfa Ezzi, Nour Douss, Sonia Saar, Marouen Tritar, Mansour Njah,
and Mohamed Mahjoub
Faculty of Medicine of Sousse, Infection Prevention and Control Department, Farhat Hached University Hospital, University of Sousse, Sousse, Tunisia
ABSTRACT
Background In the absence of a specic treatment for COVID-19, preventive measures have been
implemented to control this pandemic and vaccination is one of them. However, it is crucial to verify
the safety and eciency of every vaccine. The aim was to determinate the predictive factors of side
eects and reinfection after COVID-19 vaccine. Methods A cross-sectional study was conducted in
February 2022 among Tunisians infected with COVID-19 between March 2020 and February 2022,
using an online self-administered questionnaire. We conducted univariate and multivariate analyses
using binary stepwise logistic regression. Results A total of 1541 was selected from 1911 individuals.
Comorbidities aected a quarter of the population (22.3%). Before the initial infection, 39.3% had
received full vaccination, and 8.7% had received partial vaccination. By February 2022, the majority
(82.9%) had received at least two vaccine doses. The reinfection rate was 30.6%. All vaccines prior to the
rst infection was identied as a protective factor against reinfection. Inactivated virus vaccinations were
less likely to induce adverse eects. Conclusion ach vaccine has its own set of advantages and dis-
advantages: mRNA-based vaccines had a higher incidence of side eects but all vaccines provided better
protection against reinfection.
ARTICLE HISTORY
Received 17 October 2023
Revised 10 January 2024
Accepted 15 January 2024
KEYWORDS
COVID-19 vaccine; side
effects; reinfection; safe;
efficiency; Africa
Introduction
COVID-19 was declared a global pandemic on March 11,
2020
1
and continues to persist.
2,3
From its emergence until
August 31, 2023, the world health organization (WHO) has
recorded more than 770 million confirmed cases of COVID-19
and 7 million deaths worldwide. In the absence of a specific
treatment for COVID-19, preventive public health measures
such as mask-wearing, physical distancing, good hand hygiene,
isolation of confirmed cases and vaccination have been imple-
mented to reduce COVID-19.
4,5
However, the most effective
alternative to curb the virus’s spread, reduce severe illness and
death, and enable society to return to normalcy, is a safe and
effective vaccine with minimal side effects.
6
Vaccines are
a crucial tool, though none are 100% effective in controlling
this pandemic.
7
Multiple vaccine has been developed world-
wide using various technologies, including mRNA, viral vec-
tor, protein subunit, and inactivated virus.
7–9
The first
COVID-19 vaccines were granted emergency use authoriza-
tion in the United States by the end of 2020,
10,11
marking
a significant turning point in the battle against the pandemic.
Globally, 13 billion vaccine doses have been administered,
contributing to achieving herd immunity and reducing the
virus’s ability to spread. Post-vaccination monitoring systems
continuously track vaccine safety, and any adverse events are
thoroughly investigated.
12,13
Nevertheless, it is well under-
stood that each vaccine comes with its own set of advantages
and side effects
14,15
but the benefits of vaccination far outweigh
the risks. While COVID-19 vaccination is highly effective in
preventing infection and reducing the severity of the disease,
the possibility of reinfection exists, particularly in the context
of emerging variants and waning immunity. Reinfection can
occur due to an insufficient initial immune response to the
virus or a decline in neutralizing antibody responses over
time.
16
As of June 20, 2023, Tunisia has administered
13 million vaccine doses.
17
The Tunisian government has
approved various vaccines, including Pfizer-BioNTech,
Moderna, AstraZeneca, Sputnik V, Janssen, Sinopharm and
Sinovac, and has made them available to the entire
population.
18
Our study aims to determine the side effects
and the incidence of reinfection following COVID-19 vaccina-
tion and identify their predictive factors.
Methods
Study design
A cross-sectional study was conducted in February 2022
among the Tunisians population infected with COVID-19
between March 2020 and February 2022.
Study population
All Tunisians who had been infected with COVID-19, con-
firmed by either a rapid test or PCR at least once, and who
agree to participate in the study were included.
The sample size needed was estimated using the formula:
n=[(Z
α/2
)
2
× p × (1–p)]/i
2
. The rate of side effects considered
was 70%
19
and the prevalence of reinfection ranges from 0.3%
to 31.4%.
20–24
To optimize the sample size, a proportion (p) of
CONTACT Souhir Chelly souhirch@hotmail.fr
HUMAN VACCINES & IMMUNOTHERAPEUTICS
2024, VOL. 20, NO. 1, 2306703
https://doi.org/10.1080/21645515.2024.2306703
© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC.
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits
unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the
posting of the Accepted Manuscript in a repository by the author(s) or with their consent.

70% was selected, a precision (i) of 5% and a risk error (α) of
5% were evaluated, resulting in a necessary sample size of at
least 288 individuals and a loss of 30% due to non-eligible
participants (not being a Tunisian, under 18 years of age, ect.)
were considered, resulting in a required sample size of at least
375 participants. We excluded individuals under the age of 18,
Tunisians residing abroad, non-Tunisian residents in Tunisia,
those who were unvaccinated at the time of the study, and
those who had received mixed vaccines. In Tunisia, the popu-
lation was vaccinated with three types of vaccines: mRNA
vaccines including Pfizer and Moderna; viral vector including
Sputnik, Janssen & Janssen and AstraZeneca; and inactivated
virus vaccines including Sinovac Coronavac and
Sinopharm.
25,26
The determination of COVID-19 Variants Of Concern
(VOC) typically involves genetic sequencing of the virus.
This process can be more complex in certain countries, such
as Tunisia, due to several challenges, including limited
resources and a scarcity of national laboratories equipped for
such procedures. Consequently, the sequencing efforts have
focused on specific clusters or severe cases. According to the
Tunisian Ministry of Health, the predominant circulation of
VOCs during the study period was the Alpha variant from
December 2019 to April 2021, the Delta variant from May 2021
to December 2021, and the Omicron variant starting from
January 2022.
27
Data collection
Data was collected using an online self-administered question-
naire in both French and Arabic through Google Forms. The
questionnaire was shared on Facebook, which is considered as
the most popular social media in Tunisia,
28
as well as on radio,
and television channels for one month in February 2022, with
weekly reminders. Respondents were questioned about their
socio-demographic factors, COVID-19 infection history, rein-
fection, its impact on their health, post-COVID infection
symptoms, vaccination and side effects.
Data analysis
Data entry and analysis using the Statistical Package for Social
Sciences (SPSS) version 21.0. Quantitative variables were pre-
sented as mean and standard deviations if the distribution is
normal and compared by the t-test Student. Qualitative vari-
ables were presented as frequencies and percentages and com-
pared by chi-square test. Univariate after multivariate logistic
regression was used. All variables with a p value less than or
equal to 20% were included in the univariate analysis. The
significance threshold was set at 5%, and the strength of
association was estimated by calculating the odds ratio (OR)
and its 95% confidence interval. The rate of menstrual disor-
ders was calculated in the sub-population of women of child-
bearing age.
29
Variables’ denitions
Reinfection was defined as patients who had two positive tests
confirmed by either rapid test or PCR, taken more than 90
days apart and who had recovered clinically.
30,31
Long COVID
was defined as the persistence of current symptoms or the
emergence of new symptoms within three months after
onset, lasting at least two months, and having no differential
diagnosis.
32
Safety was defined by presence or absence of post-
vaccination adverse effects.
33
Ethics approval and consent to participate
The Farhat Hached University Hospital’s Ethical Committee
(Institutional Review Board code:00008931) approved this
study, and it was carried out in accordance with the ethical
principles the Declaration of Helsinki (CER:34–2022 is the
reference number for the committee’s opinion). The Google
form’s two sections were preceded by an introductory para-
graph that described the study’s goals and methodology.
Responses’ anonymity was emphasized. The first element of
the Google form required participants to indicate their agree-
ment to participate in the study by selecting “yes” in response
to the following question: “Do you agree to participate in the
study?” This action was required in order for them to access
the questionnaire. The user of the link was not given the
questionnaire if they selected “No” as their response. Full
names and e-mail addresses were not collected to ensure
anonymity and confidentiality.
Results
General characteristics of the population
Among the 1911 participants, 1541 were selected. The sex
ratio F/M was 3.98 with an average age of 37.27 ± 9.25 years,
which serves as the population’s cutoff point. The Tunis
governorate had the highest participation (19.4%), followed
by the Sousse governorate (16.1%), Ariana governorate
(10.8%), Ben Arous governorate (8.8%), and Sfax governor-
ate (6.4%). Regarding participants’ lifestyle habits, 18.6%
were active smokers and 11.8% were alcohol consumers.
About 39.1% of the population was overweight and 18.8%
were obese. Comorbidities affected a quarter of the popula-
tion (22.3%), with respiratory problems (6%), hypertension
(5.4%), thyroid disorder (5.5%), and diabetes (3.8%). A total
of 937 (60.8%) people received the mRNA Pfizer-BioNTech
vaccine, 221 (14.3%) received the mRNA Moderna vaccine,
180 (11.7%) received the adenovirus vector AstraZeneca
vaccine, 75 (4.9%) received the adenovirus vector Janssen
& Janssen vaccine, 77 (5.0%) received the inactivated
Sinopharm vaccine and 51 (3.3%) received the inactivated
Sinovac Coronavac vaccine. We did not identify any subjects
vaccinated exclusively with Sputnik, as all of them had
a mixed vaccination schedule (and were excluded from the
study) because those exclusively vaccinated solely with
Sputnik had not received their vaccine pass.
Side eects following COVID-19 vaccination
Side effects were reported by 76.8% of participants (n = 1184)
at the time of the study. Regarding local side effects, redness
was the most frequent (34.1%). Fatigue (47.6%), headache
2S. CHELLY ET AL.

(45.5%), fever (32.1%), and arthralgia (30.5%) were the most
common systemic adverse symptoms (Table 1).
In the univariate analysis, females were more susceptible to
developing side effects (p = .003; OR = 1.51[1.14–2.00]). The
use of mRNA-based and adenovirus vector vaccines signifi-
cantly increased the likelihood of experiencing side effects
compared to inactivated virus vaccine (p = .002, OR = 1.51
[1.16–1.96]). For individuals aged 37 and above, who were
smokers, alcohol consumers, obese, and had at least one
comorbidity, the difference was statistically insignificant.
Respiratory comorbidities (p = .102), hypertension (p = .742),
diabetes (p = .600), and thyroid disorder (p = .236) also showed
no statistical significance (Table 2).
Reinfection
More than half (52%) had been infected with the virus prior to
vaccination. Before the initial infection, 39.3% had received
full vaccination and 8.7% had received partial vaccination
against COVID-19. A total of 528 (34.2%) received mRNA
vaccine, 141 (9.1%) received adenovirus vector vaccine and 71
(4.6%) received inactivated vaccine. The rate of reinfection was
30.6%. Among the 472 participants who underwent a second
infection, the majority (82.4%) were not reinfected by the same
VOC. A small percentage reported a third infection (5.1%),
with 88.6% of these cases associated with a different VOC
compared to their initial infection.
In the univariate analysis, vaccination with two doses prior
to the first infection was a protective factor against reinfection
(p = .001; OR = 0.49 [0.31–0.76]), all types of vaccine were
protective against reinfection. Obesity (BMI ≥ 30) was also
Table 1. Side effects of vaccine.
Side effect N = 1184%)
Local Redness 526 (34.10)
Pain 4 (0.25)
Systemic Intermittent fever 495 (32.10)
Fatigue 734 (47.60)
Arthralgia 470 (30.50)
Muscle pains 368 (23.90)
Headaches 535 (34.70)
Dizziness 5 (0.32)
Epigastralgy 5 (0.32)
Vomiting 7 (0.45)
Nausea 7 (0.45)
Chest pain 14 (0.90)
Cough 9 (0.58)
Tachycardia 7 (0.45)
Menstrual disorder 11 (1.05)
Table 2. Univariate analysis of the side effect.
Variable
Side effect
pOR [CI 95%]Yes n (%) No n (%)
Gender
Female 966 (78.4) 266 (21.6) .003 1.51 [1.14–2.00]
Male 218 (70.6) 91 (29.4) Reference
Vaccine categories
mRNA 912 (78.8) 246 (21.2) .002 1.51 [1.16–1.96]
Viral vector/Inactivated virus 272 (71.0) 111 (29.0) Reference
Types of vaccine
Inactivated virus 68 (53.1) 60 (46.9) Reference
Viral vector 204 (80.0) 51 (20.0) ≤ 10−3 3.52 [2.22–5.60]
mRNA 912 (78.8) 246 (21.2) ≤ 10−3 3.27 [2.24–4.75]
Comorbidities
Yes 264 (77.0) 79 (23.0) .947 -
No 920 (76.8) 278 (23.2)
Age range (years old)
≤37 634 (76.8) 192 (23.2) .930
>37 550 (76.9) 165 (23.1) -
Tabacco
Yes 216 (75.5) 70 (24.5) .560 -
No 968 (77.1) 287 (22.9)
Alcohol
Yes 135 (74.2) 47 (25.8) .366 -
No 1049 (77.2) 310 (22.8)
Obesity
Yes 226 (78.2) 63 (21.8) .540 -
No 958 (76.5) 294 (23.5)
The multivariate analysis showed that females (p = .003, OR = 1.54 [1.16–2.05]), mRNA-based vaccines and adenovirus vector
were more predictive of side effects than inactivated vaccine (Table 3).
Table 3. Multivariate analysis of the side effect.
Variable
Side effect
pOR [CI 95%]Yes n (%) No n (%)
Gender
Female 966 (78.4) 266 (21.6) .003 1.54 [1.16–2.05]
Male 218 (70.6) 91 (29.4) Reference
Types of vaccine
Inactivated virus 68 (53.1) 60 (46.9) ≤ 10−3 Reference
Viral vector 204 (80.0) 51 (20.0) ≤ 10−3 3.60 [2.26–5.73]
mRNA 912 (78.8) 246 (21.2) ≤ 10−3 3.30 [2.26–4.80]
HUMAN VACCINES & IMMUNOTHERAPEUTICS 3

a predictive factor of reinfection (p = 0.020; OR = 1.37 [1.05–
1.80]). Among individuals aged 37 and older who were smo-
kers, alcohol consumers, obese, and had at least one comor-
bidity, there was no statistically significant difference.
Respiratory comorbidities (p = .905), hypertension (p = .728),
diabetes (p = .758), and thyroid disorder (p = .199) similarly
exhibited no statistical significance (Table 4).
Long COVID
Complete vaccination protects against long COVID (p ≤ 10
−3
;
OR = 0.49[0.31–0.76]). Reinfection is considered a risk factor
for long COVID (p = .002; OR = 1.32[1.04–1.66].
Discussion
While COVID-19 vaccines have demonstrated a high level
of safety in clinical trials, there is less statistical data
comparing their safety in real world usage.
13
To our knowl-
edge, few studies worldwide such as in the Middle East
(Iraq, Jordan, Bahrain) and India
19,34–39
have compared the
side effects among the three types of COVID-19 vaccines in
the general population and none of them have been con-
ducted in North Africa except for one study that focused
on Algerian athletes.
40
However, side effects are considered
reactogenicity symptoms which are a consequence of the
expected immune response to immunization. In fact, the
extent of reactogenicity, whether local or systemic, is influ-
enced by a multitude of factors, including host character-
istics (such as age and gender), vaccine features and
various other elements.
41
In this study we found that
76.8% of participants reported side effects regardless of
the type of vaccine. Fatigue (47.6%), headache (45.5%),
fever (32.1%), and arthralgia (30.5%) were the most com-
mon systemic adverse symptoms. These findings align with
those reported in numerous other studies regarding the
Table 4. Univariate analysis of the reinfection.
Variable
Reinfection
pOR [CI 95%]Yes n (%) No n (%)
Gender
Female 375 (30.4) 857 (69.6) .740 -
Male 97 (31.4) 212 (68.6)
Types of vaccine
Non-vaccinated 340 (42.4) 461 (57.6) ≤ 10−3 Reference
mRNA 80 (15.2) 448 (84.8) ≤ 10−3 0.24 |0.18–0.31]
Viral vector 39 (27.7) 102 (72.3) 0.001 0.51 [0.34–0.76]
Inactivated virus 13 (18.3) 58 (81.7) ≤ 10−3 0.30 [0.16–0.56]
Complete vaccination before first infection
Yes 95 (15.7) 510 (84.3) ≤ 10−3 0.49 [0.31–0.76]
No 37 (27.4) 98 (72.6) Reference
Comorbidities
Yes 105 (30.6) 238 (69.4) .990 -
No 367 (30.6) 831 (69.4)
Age range (years old)
≤37 249 (30.1) 577 (69.9) .650 -
>37 223 (31.2) 492 (68.8)
Tabacco
Yes 88 (30.8) 198 (69.2) .950 -
No 384 (30.6) 871 (69.4)
Alcohol
Yes 61 (33.5) 121 (66.5) .360 -
No 411 (30.2) 948 (69.8)
Obesity
Yes 105 (36.3) 184 (63.7) .020 1.37 [1.05–1.80]
No 367 (29.3) 885 (70.7) Reference
The multivariate analysis revealed that an incomplete vaccination schedule before the first infection (p ≤ 10
−3
; OR = 0.48 [0.30–0.75]) was
protective factor of reinfection. However, obesity (p = .028; OR = 1.67 [1.05–2.64]), adenovirus vector vaccine (p ≤ 10
−3
; OR = 2.14 |1.37–
3.34]) were more predictive of reinfection (Table 5).
Table 5. Multivariate analysis of the reinfection.
Variable
Reinfection
pOR [CI 95%]Yes n (%) No n (%)
Types of vaccine
Non-vaccinated 340 (42.4) 461 (57.6) ≤10−3 Reference
mRNA 80 (15.2) 448 (84.8) ≤10−3 0.24 |0.18–0.31]
Viral vector 39 (27.7) 102 (72.3) .001 0.51 [0.34–0.76]
Inactivated virus 13 (18.3) 58 (81.7) ≤10−3 0.29 [0.15–0.54]
Complete vaccination before first infection
Yes 95 (15.7) 510 (84.3) .002 0.49 [0.31–0.76]
No 37 (27.4) 98 (72.6) Reference
Obesity
Yes 105 (36.3) 184 (63.7) .017 1.40 [1.06–1.86]
No 367 (29.3) 885 (70.7) Reference
4S. CHELLY ET AL.

most prevalent side effects.
13,15,42–46
Initially, mRNA vac-
cines were believed to carry no risk of reactivation and
were thought to be safer than inactivated vaccines.
46,47
However, the findings of our study revealed that side
effects were more common among mRNA vaccines than
adenovirus vector vaccines and inactivated vaccines. Other
studies support our results when comparing mRNA and
inactivated vaccines
35,36,43
or mRNA and adenovirus vector
vaccine
13,35,37,42
or adenovirus vector and inactivated
vaccine,
19,35,48,49
but no study has compared all three
types of vaccine. For most vaccines, these reactions are
mild to moderate and temporary,
26,43,44
with no serious
adverse event.
50–52
Another noteworthy finding is the con-
siderable variation in side effects based on gender, with
a higher prevalence of events in females compared to
male as reported in the majority of the studies
worldwide,
34,39–42,43,53–56
which is consistent with our
results. Additionally, other predictive factors for side effects
have been reported in previous studies, such as age,
34,55
comorbidities as diabetes, hypertension, asthma, thyroid
disorder,
34,43
or weight status,
45
but no significant associa-
tion were found in our study. The lack of statistical sig-
nificance regarding the age variable in our sample may be
attributed to older subjects having limited access to the
internet compared to younger subjects. At the present,
the precise reason for the presence or the absence of
association between chronic diseases and side effects is
still unclear. Nonetheless, it is suggested that additional
forward-looking studies with a larger sample size are
needed to confirm or infirm this correlation. It is well
established that vaccines do not provide immunity to all
vaccinated individuals.
57
The reasons for this variability are
numerous, ranging from genetic and immunological factors
to the quality of the vaccines themselves and their
administration.
26
Despite significant disparities in the pre-
valence and severity of side effects among these vaccina-
tions, statistical analysis suggested that vaccines may offer
similar protection against severe forms of COVID-19.
19
Hence, the importance of studying these factors in the
Tunisian population and identifying their specific charac-
teristics. Indeed, the reinfection rate found in our study
was 30.6% falling within the range reported in the litera-
ture (which ranges from 0.3% to 31.4%).
20–24
This variation
can be attributed to various factors, including the absence
of a consensus definition of reinfection,
58
the presence of
different virus variants (such as Omicron, which is the
most active
59
), vaccination rates, population herd immunity
level, infection prevention strategies and recipient
characteristics.
60–62
In our survey, receiving two vaccine
doses prior to the first infection was a protective factor
against reinfection. This finding is supported by several
studies that have demonstrated that full vaccination pro-
vides additional protection against reinfection.
63–67
While
full vaccination does not completely eliminate the risk of
reinfection, it contributes significantly to controlling the
pandemic by reducing the incidence symptomatic cases,
critical cases, and fatalities.
68
Researchers have reported
high vaccine efficacy levels, with Pfizer, Moderna and
Sputnik V exceeding 90%, AstraZeneca and Janssen &
Janssen above 70% and Sinopharm reaching an efficacy of
79%.
34,44,69,70
When comparing the three types of COVID-
19 vaccine, mRNA-based vaccination showed a more sig-
nificant decrease in the risk of reinfection compared to
adenovirus vector. This observation is consistent with find-
ings in the literature, which confirm that individuals vacci-
nated with Pfizer or Moderna are less likely to develop
severe symptoms upon reinfection, experience fewer hospi-
talizations, and have lower mortality rates.
66,67,71–73
Another notable finding in this study was that obese indi-
viduals were more susceptible to reinfection. Vaccine effec-
tiveness appears to be reduced in individuals with
obesity
74–78
due to the inappropriate immune response.
Prioritizing strategies to achieve and maintain a healthy
weight could potentially increase vaccine efficacy and
reduce the risk of severe COVID-19 infections in this
population.
74,79
Encouraging healthy eating habits, physical
activity, and weight reduction should be emphasized.
80
The
low rate of reinfection among vaccinated individuals in our
study indicates that immunity produced by vaccination
remains effective despite the ongoing mutation of the
COVID-19 virus and the emergence of new VOCs. While
there is controversy, one meta-analysis reported that cer-
tain variants (Beta, Gamma and Delta) may have the ability
to evade immunity induced by vaccination.
81
Nevertheless,
overall, study results indicate that vaccination conferred
immunity is likely to protect against severe forms of the
disease, and that the vaccine remains effective against the
majority of VOCs.
81
This survey also revealed that indivi-
duals suffering from long-COVID syndrome were more
vulnerable to reinfection. However, studies have primarily
explored the other aspect of this relationship between long
COVID and reinfection to ascertain that reinfection could
have significant consequences in terms of morbidity and
could be further complicated by long COVID.
82–86
Limits of the study
While online questionnaires are convenient tools with benefits
such as access to a diverse population and rapid responses,
certain issues may arise during the completion of the ques-
tionnaire. Additionally, we relied on self-reported data for
weight and height, the reliability and validity of which have
been found to be inconsistent in previous investigations.
Moreover, given the anxiety associated with this emerging
pandemic, the side effects experienced by each individual,
regardless of gender and age, are a highly individualized
experience with specific psychological implications for each
person. Therefore, the findings should be evaluated and ana-
lyzed while considering all the factors mentioned above.
Strengths of the study
This study can be considered representative of the general
Tunisian population, particularly because the participants
were from all 24 governorates of Tunisia. Furthermore, to
the best of our knowledge, this is the first North African
study that has compared the rates of side effects and reinfec-
tion and their predictive factors for the three types of vaccines
HUMAN VACCINES & IMMUNOTHERAPEUTICS 5

(mRNA, adenovirus vector, and inactivated vaccines) in the
same general population, with a large sample size.
Identifying factors predictive of side effects and reinfection
after vaccination with COVID-19 is imperative for improving
the vaccine’s safety and efficacy. It also helps to strengthen
public confidence in vaccination. Vaccination recommenda-
tions based on individual characteristics reinforce safety
measures and promote personalized vaccination strategies.
Large-scale population studies on side effects are essential for
effective communication, promoting transparency and trust in
vaccination programs, and increasing adherence to vaccina-
tion campaigns. Analysis of viral reinfection also provides
important information for decisions on booster injections
and long-term efficacy. The vaccine also protects against long
COVID. Taking population-specific factors into account is
essential for tailoring vaccination strategies, and contributes
to global health equity.
Conclusion
Although the rapid development of vaccinations represents an
exceptional scientific achievement, it has raised significant
concerns regarding safety and efficacy, contributing to vaccine
hesitancy. Our study revealed that each vaccine has its own set
of advantages and disadvantages: mRNA-based vaccines were
associated with more side effects but offered greater protection
against reinfection. Nevertheless, all vaccines appear to be
effective in preventing severe reinfection and are generally
considered safe.
Declaration
Ethical approval and consent to participate
The Farhat Hached University Hospital’s Ethical Committee
(Institutional Review Board code:00008931) approved this
study, and it was carried out in accordance with the ethical
principles the Declaration of Helsinki (CER:34-2022 is the
reference number for the committee’s opinion). Participants
gave informed consent via an online form at the beginning of
the survey, which was approved by the ethics committee.
Acknowledgments
We would like to express our gratitude to all the individuals and groups
who have shared the questionnaire link on Facebook. We also extend our
thanks to all the radio and TV channels that have allowed us to distribute
the questionnaire.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
The author(s) reported there is no funding associated with the work
featured in this article.
Authors’ contributions
The authors SC and SJ designed the work. SC, MT, SS and SJ participated
in data analysis and interpretation. SC, SJ, AA, OE and MM drafted the
work. SC and ND revised it. SC, MM and MN supervised all the steps of
the manuscript editing. All authors approved the final version of the
manuscript, agreed to be personally accountable for their own contribu-
tions and ensure that questions related to the accuracy or integrity of any
part of the work, are appropriately investigated and resolved. All authors
read and approved the final manuscript.
Data availability statement
The datasets used and/or analyzed during the current study available from
the corresponding author on reasonable request.
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