The prevalence of potential side effects of COVID-19 vaccines among vaccinated Iraqi people: a prospective cross-sectional study

The coronavirus disease 2019 (COVID-19) produced by severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) reportedly infected and killed millions of people (Dong, Du, & Gardner, 2020). Coronavirus appeared originally from Wuhan in China in 2019 and spread all over the world. In the middle of 2021, its morbidity was more than 170 million, and its mortality was close to four million (Wu & McGoogan, 2020). The research community made an immediate international request to create vaccines (Kaur & Gupta, 2020). Doubts about the effectiveness of vaccines have been imposed with respect to short-term evaluation and long-term adverse reactions (Harrison & Wu, 2020). This is regarded as one of the main challenges that has been connected to population acceptance of COVID-19 vaccines varying widely.

The efficiency of Pfizer and AstraZeneca vaccines was reported to be 95% and 70%, respectively (Voysey et al., 2021). The Chinese vaccine Sinopharm was the first to be admitted to Iraq (Funk, Laferrière, & Ardakani, 2021). The total number of vaccinated people in Iraq until Apr 28, 2022, is 10,524,458. Several research studies in different countries have corroborated the fact that the fear of vaccine side effects is the most prominent and common cause of vaccination avoidance (Luyten, Bruyneel, & van Hoek, 2019; Szmyd et al., 2021). According to Al-Mufty et al., the postvaccination side effects of the three vaccines were mild to moderate in severe (Almufty, Mohammed, Abdullah, & Merza, 2021). Furthermore, a recent study demonstrated that the most side effects shown were fatigue, reactions to the site of injection, fever, myalgia and a headache and cold in equal measure (Albasry & Al-Taie, 2023).

However, Iraqi people have their fears regarding these vaccines, some are certain about conspiracy theories. Other reasons contributing to low vaccination attendance include potential side effects and a lack of trust in manufacturing sectors (Harrison & Wu, 2020). These factors prompted the necessity for an evaluation of the postCOVID-19 vaccination adverse effects of various vaccine companies existing in Iraq. Hence, the current study aimed to estimate the prevalence of side effects from three vaccines and to compare the potential side effects of these vaccines.

This cross-sectional study was conducted in Baghdad, Iraq from May 2021 to March 2022. To collect information on postvaccination side effects among the Iraqi people, a standard survey tool based on Google Form was used. The survey included three main parts: demographic information (age and gender); health history (chronic diseases, previous infection with coronavirus before vaccination and severity of the infection) and vaccines information (type of vaccine, symptoms of postvaccination and the intensity of symptoms). To maintain the privacy of the participants, questions such as name and other personal information were not included in the survey. Ethical approval was not included as the study was based on the survey, and there was no direct contact with the participants. However, the study and the purpose of this survey were fully explained to the participants in the beginning of the questionnaire, and the consent form was obtained.

The survey was sent to the participants through social media, i.e. WhatsApp, Messenger and Google Classroom, and only the vaccinated people were included in the study. A convenient sample using snowball sampling methodology was used. When the population is unknown, the sample size can be derived by computing the minimum sample size required for accuracy in estimating proportions by considering the standard normal deviation set at 95% confidence level, and the confidence interval of 5% (Albasry & Al-Taie, 2023). However, a total of 737 vaccinated participants were included in this study. The age of participants was categorized into 18–30, 31–40, 41–50, 51–60 and ≥60 years old. All the participants had received, at least, the first dose of the COVID-19 vaccine.

The Statistical Package for Social Sciences software version 28.0 (Chicago, USA) was used for the statistical analysis of the research data. The percentages of demographic variables for the sample under study were extracted to know the characteristics of the samples such as gender, age and other variables. The chi-square test was used to test the relationship between the type of vaccine and the potential side effects among participants.

Among the study population, 328 (44.5%) were males and 409 (55.5%) were females. The majority of the participants were aged 18–30 years old (79.10%) followed by 31–40 years (12.10%), 41–50 years (4.20%), 51–60 years (2.40%) and 60≥ years (2.20%). The enrolled participants had received Pfizer-BioNTech (58.8%) followed by AstraZeneca-Oxford (23.7%) and Sinopharm (17.5%). Among them, 56.60% showed postvaccinated side effects, 33.0% showed no side effects, whereas 10.40% were not sure. Table 1 demonstrates the demographic characteristics of the participants. The side effect symptoms by gender are shown in Table 2 while the side effect symptoms by age groups of the participants were listed in Table 3.

The most common postvaccination side effects were fever 407 (25.2%), general fatigue 355 (22.0%), headache 282 (17.4%) and joint pain 218 (13.5%). Figure 1 illuminates the postvaccination side effects. Table 4 showed the recurrences of symptoms among the three vaccines employed in this study. There was a significant relationship (p > 0.05) between the symptoms of shivering, nausea, fatigue, joint pain, headache, dizziness, fever and the type of vaccine employed. The other symptoms have no significant (p < 0.05).

COVID-19 infection continues as a pandemic that strikes the entire world including Iraq. However, the vaccines emerged to control and lower the death rate of the disease. The vaccines were showing different postvaccination side effects.

Among the age group, 18–30 years old were the highest to be vaccinated (79.10%) while 60 years old and above were the lowest (2.20%) (Table 1). Similar findings were seen in a recent report where the age groups 50–69 and 70 above were the lowest to be vaccinated (Almufty et al., 2021). This is maybe due to that the present survey was online and not all those in these age groups were aware of using the net. However, the age group (18–30 years) mostly was students and government employees which they have strictly imposed to get vaccinated.

Among the study population, 58.8%, 23.7% and 17.5% were received Pfizer-BioNTech, AstraZeneca-Oxford and Sinopharm, respectively. Similar results were declared in the previous reports (Attash, Al-Obaidy, & Al-Qazaz, 2022). The high intake of Pfizer-BioNTech vaccine was due to well reputation of Pfizer Company among the Iraqi individuals. However, Pfizer vaccine showed up to 95 % efficacy against the coronavirus (Rahman et al., 2022). Nevertheless, in Iraq, Sinopharm vaccine was on-demand at the beginning of vaccination but due to the lack of supplies of the vaccine made it at the last of the list.

In the present study, 56.60% of vaccinated participants exhibited side effects (moderate to severe) while 33% experience no side effects, and 10.40% were not sure (Table 1). This finding is in line with observational study in United Arab Emirates reported by Ganesan et al., which found that only 5% of the participants needed hospital treatment while the rest of vaccinated participants showed mild side effects (Ganesan et al., 2022). The current data revealed that 53.90% of vaccinated participants were not infected by COVID-19 before vaccination while 37% were previously infected (Table 1). The previous infection of COVID 19 was reported to be in concordance with the high frequency of postvaccination side effects (Almufty et al., 2021; Menni et al., 2021). However, there is no obvious reason; this might be related to an increased immune response as a consequence of vaccination (Menni et al., 2021).

The most common side effects was fever 407 (25.2%), general fatigue 355 (22.0%), headache 282 (17.4%) and joint pain 218 (13.5%) while the less showed side effects were vomiting and abdominal colic 2 (0.1%) (Figure 1). This is in accordance with recent reports from different countries were shared similar side effects such as fever, fatigue, headache and joint pain (Almufty et al., 2021; Attash et al., 2022; Rahman et al., 2022).

Moreover, 57.0% of the participants who took Pfizer vaccine showed fever in comparison with AstraZeneca (33.2%) and Sinopharm (9.8%) vaccines, respectively. Similar findings were presented in recent studies (Riad et al., 2021; Zhu et al., 2020). There was a significant relationship between indigestion and the type of vaccine used (p > 0.05). Furthermore, a significant relationship (p > 0.05) was shown between the side effects of shivering, nausea, general fatigue, arthritis, headache, dizziness, fever and the type of vaccine employed (Table 4). Moreover, no significant relationship was seen between other symptoms and types of vaccines (Table 4). However, recent studies showed that the symptoms such as fever, fatigue, indigestion, nausea, dizziness and diarrhea were associated more with AstraZeneca vaccine than Pfizer and Sinopharm (Rahman et al., 2022; Riad et al., 2021). This is not in accordance with the present study due to the number of participants who acquired Pfizer vaccine in this study being higher than the rest of the vaccines (Table 4). There was a strong relationship between vaccination type and side effect prevalence, with AstraZeneca and Pfizer having the greatest rates of side-effects compared to the Sinopharm vaccine (Table 4). Old participants were noted to have asymptomatic to very mild symptoms. These data were consistent with the Food and Drug Administration (FDA)’s study, which believed that those over the age of 55 years were less likely to experience side effects (Abukhalil et al., 2023). In addition, a research study revealed that young individuals were more certain to experience adverse effects with the Pfizer vaccination (Riad et al., 2021). Measured trials on the effectiveness and safety of AstraZeneca vaccine in different countries also showed a reduction in the quantity and severity of adverse effects in older individuals (Voysey et al., 2021). Generally, younger people generate higher immunological reactions than elderly adults (Voysey et al., 2021). In correspondence, younger individuals tend to have more frequent and severe side effects.

In the present study, the majority of the side effects were reported after the first dosage, which was in accordance with the Attash et al., in Iraq and Hatmal et al., in Jordan (Attash et al., 2022; Hatmal et al., 2021) while El-Shitany et al. noticed that the adverse effects arose after the second dosage (El-Shitany et al., 2021). According to Polack et al., similar side effects were observed following the first and second dosages of the vaccine (Polack et al., 2020). As per the Centers for Disease Control and Prevention, the intensity of symptoms increased following the second dosage. All the participants were experienced pain at the site of injection. However, recent studies showed that people who received Pfizer vaccine were experienced more pain at the site of injection followed by AstraZeneca and Sinopharm (Almufty et al., 2021; Attash et al., 2022).

Among the participant who received Pfizer and AstraZeneca vaccines, systemic effects were shown varies symptoms. Individuals who got the Pfizer and AstraZeneca vaccinations experienced considerably higher frequency (p < 0.05) of systemic side-effects such as fever, headache, shivering and dizziness (Table 4).

With respect to intestinal tract symptoms (colic, colitis, nausea, constipation, diarrhea, vomiting, loss of appetite and indigestion), very less participants demonstrated these symptoms; therefore, no significance (p < 0.05) was shown among the types of vaccines (Table 4). This is contrary to Attash et al., who reported a great association of vomiting and nausea with AstraZeneca vaccine (Attash et al., 2022). Furthermore, very less individuals experienced tachycardia and difficulty in breathing (Table 4), which is not in comparable to the previously reported studies (Almufty et al., 2021; El-Shitany et al., 2021; Rahman et al., 2022). In an Iraqi study, breathlessness was more common among AstraZeneca vaccination participants (Almufty et al., 2021), whereas it was uncommon in Saudi Arabia; it did affect a small number of people (El-Shitany et al., 2021). Moreover, in an Indonesian study, 1 % of the vaccinated individual showed breathing difficulties (Djanas et al., 2021).

Those who received Pfizer and AstraZeneca vaccination showed higher symptoms of joint pain in contrast to Sinopharm (p > 0.05) (Table 4). Different studies around the world showed a different percentage of joint pain symptoms such as in Jordan (around 50%) (Hatmal et al., 2021), In Bangladesh (12.52%) (Sultana et al., 2021) while only 2% in Saudi Arabia (Alhazmi et al., 2021). Loss of taste and smell and sleeplessness were also reported in other studies (Almufty et al., 2021; Jayadevan, Shenoy, & Ts, 2021; Riad et al., 2021).

There are certain limitations in the study. First, since this is a descriptive cross-sectional study employing an online survey, only those who often use the network enrolled in the report. Therefore, elder individuals were low. Second, the study was designed to report the vaccinations' short-term side effects; however, a long-term follow-up investigation in the general population is necessary. Third, the study is not representative of the entire Iraqi population, the study included participants who resided in Baghdad. Fourth, a large cohort study is required to understand the differences of side effects.

The study revealed that the participants who took the Pfizer and AstraZeneca vaccinations complained of fever, fatigue, headache, joint pain and dizziness. However, the post-vaccination symptoms were mild to moderate in intensity and were tolerable. Sinopharm was the lowest vaccine developed post side effects. Further studies are warranted to understand the molecular biology of the virus and expected mutation.