Pfizer-BioNTech COVID-19 Vaccine (BNT162b2) Side Effects: A Systematic Review

Vaccinations prevented severe clinical complications of COVID-19. It was considered a vital component of living endemically with COVID-19. The Pfizer-BioNTech vaccine is the first mRNA-based vaccination that enhances immunity. Resulting in various adverse effects that may emerge after vaccination. This systematic review was undertaken to assess the Pfizer-BioNTech vaccine side effects by reviewing the previous studies. A total of 107 PubMed and Google Scholar publications were screened for Pfizer-BioNTech COVID-19 vaccine side effects. Fourteen articles met the study inclusion criteria. The included searching terms were a combination of “Pfizer vaccine and Side effects,” “BioNTech vaccine and side effects,” and “BNT162b2 vaccine and side effects,” as well as all synonyms. The total number of participants in the 14 studies was 10,632 participants. Average of the most frequent side effects of 14 studies were injection site pain 77.34%, fatigue 43%, muscle pain 39.67%, local swelling 33.57%, headache 33.27%, joint pain 25.75%, chills 18.34%, fever 18%, itching 9.38%, lymph nodes swelling 7.86%, nausea 7.58%, dyspnea 7.86%,and diarrhea 6.36%. The average side effects after the first dose were 79% compared with 84% after the second dose. The average occurs side effects in females at 69.8% compared with males 30.2%. Our study reveals that side effects after the Pfizer-BioNTech vaccine are common, but they are usually mild and self-limited. Local reactions like pain at the injection site are the most common. Anaphylactic shock or severe reactions are rare. We hope that our results will reassure the public that the benefits of vaccination far exceed the dangers. Also, help reduce vaccine hesitancy among individuals worried about vaccine safety and possible adverse effects.


Introduction And Background
Coronavirus 2 (SARS-CoV-2) emerged at the end of 2019 and quickly spread worldwide, causing a significant mortality and morbidity rate. As a result, SARS-CoV-2 was labeled a global pandemic by the World Health Organization in March 2020 [1,2]. SARS-CoV-2 infections can result in many clinical symptoms, ranging from asymptomatic or mild infections to severe lung and multi-organ infections resulting in death [3,4]. In addition, new SARS-CoV-2 variations have evolved due to the high transmission rates, posing a new challenge in managing the current epidemic [5][6][7].
Although governments and organizations all over the globe have taken many precautions to prevent the pandemic's spread, the only way to stop the threat is to find a vaccine [8]. Pfizer-BioNTech, Moderna, Sinopharm, Sinovac, Sputnik V, Janssen (Johnson & Johnson's), and AstraZeneca were among the companies that have produced COVID-19 vaccines to combat the pandemic [9,10]. These vaccines are efficient in preventing COVID-19 infection at varying levels of efficiency; however, each type of vaccination has its unique structure, pros, and cons in efficacy, immunogenicity, and safety [11][12][13]. The US Food and Drug Administration (FDA) approved the emergency use of the Pfizer-BioNTech COVID-19 vaccine on December 11, 2020 [14].
The Pfizer-BioNTech vaccines rely on messenger RNA technology (mRNA). The coronavirus has a spikeshaped surface feature known as an S protein [15][16][17][18]. mRNA vaccines are a new technique that has just been developed for possible application in vaccine manufacture, and several are now being tested [19]. Pfizer-BioNTech vaccine (BNT162b2), on the other hand, is regarded as the first mRNA-based vaccination for infectious illnesses to be authorized for human use. As a result of increasing immunity, several side effects may arise after vaccination. Some of the symptoms were muscle discomfort, fatigue, headache, fever, swelling, joint pain, tingling, itching, and chills [20]. However, it is still challenging to predict all the side effects of the Pfizer-BioNTech COVID-19 vaccine's mRNA technology because it's new [21].
The adverse effects profile is a critical component of the vaccination needed by medical care systems and public health [22]. However, to our knowledge, no review study has been conducted on the side effects of the Pfizer-BioNTech COVID-19 vaccine. In this regard aim, this systematic review was undertaken to discover adverse effects of vaccinated people and to offer information on the BNT162B2 vaccine's side effects.

Materials and methods
This research follows the Preferred Reporting Items for Systematic Reviews (PRISMA) checklist requirements for systematic reviews and meta-analyses [23]. We searched in PubMed and Google Scholar databases for studies related to the side effects of the Pfizer-BioNTech COVID-19 vaccine. From 2021 to 2022, to pick eligible research publications. Several medical subject headings terms were used for searching purposes, including a combination of "Pfizer vaccine and Side effects," "BioNTech vaccine and side effects," and "BNT162b2 vaccine and side effects" as well as all synonyms. All titles and abstracts generated from this primary investigation were rigorously edited to ensure no relevant studies were missing. Following that, the data were analyzed to identify only original research papers assessing the side effects of the Pfizer-BioNTech COVID-19 Vaccine. The second stage was to establish the inclusion criteria and exclusion criteria for studies. Abstracts were manually screened to identify relevant studies for revision. The inclusion criteria were studies on the side effects of the Pfizer-BioNTech COVID-19 Vaccine. In addition, cross-sectional or retrospective cohort or prospective cohort studies were included. Experimental studies, preclinical studies, and review articles were excluded. However, published research in a language other than English was excluded from the systematic review. The last step included collating and summarizing the pre-defined data from the final record of qualifying articles. The data evaluation process began with a preliminary examination; data were retrieved using a specifically constructed excel sheet. The excel sheet was then used to update selected data from eligible research publications. Finally, we analyzed all studies published by a single research group that examined comparable factors for any potential duplication.

Result
A total of 107 PubMed and Google Scholar publications were screened for Pfizer-BioNTech COVID-19 vaccine side effects. Forty duplicates and 25 irrelevant were removed, and 42 articles were reviewed at the abstract level. Fifteen irrelevant abstracts were removed. After removing abstracts not meeting the inclusion criteria, 27 full-text articles were reviewed. Of these, 13 articles did not meet the inclusion criteria. The exclusion was because did not include cross-sectional or retrospective cohort or prospective cohort studies or articles in a non-English language. Fourteen articles met the study inclusion criteria and contributed to this systematic review ( Figure 1).

FIGURE 1: Study selection process using preferred reporting items for systematic reviews and meta-analyses (PRISMA).
The total number of participants in the 14 studies was 10,632, who reported at least one or more side effects (   Table 1. All included studies were written in English. Side effects on the local level were more prevalent than adverse effects on the systemic level. Females suffer more side effects than males. Following the second dosage, there were greater adverse effects than the first. After the first dose, the average side effects were 79% and 84% after the second dose. However, in most subjects, adverse effects were mild and short-term. Anaphylactic shock or severe reactions are rare.

Author and publication year Method Result and main findings
Mohammed et al. Participant's average age was (21.5 ±1.7 years). The study revealed a significant difference between the number of females (96.5%) and males (85%) who suffered from the side effects of the Pfizer-BioNTech COVID-19 Vaccine (P<0.033). Male had the highest incidence of muscle pain (70%) compared to females (66.1%). (62.6 %) of females reported feeling tired, compared to (50%) of males. For headache, the results showed a significant difference between females and males, Where the percentage of females was (60.9%), compared to (35%) for males (P<0.048). Finally, there were no clear differences in the percentage of fever between females and males, as it was (49.6%) for females and (50%) for males (P > 0.999). Average of the most frequent side effects of 14 studies were injection site pain 77.34%, fatigue 43%, muscle pain 39.67%, local swelling 33.57%, headache 33.27%, joint pain 25.75%, chills 18.34%, fever 18%, itching 9.38%, lymph nodes swelling 7.86%, nausea 7.58%, dyspnea 7.86%, and diarrhea 6.36% ( Table 2). Injection site pain considers the most often occurring local adverse effect. Followed by fatigue is considered the most often occurring systemic adverse event. Maximum side effects of injection site pain reported in Krótki    participants.

Discussion
Preventive measures to limit SARS-CoV-2 transmission have been implemented globally since the COVID-19 pandemic began in January 2020 [38,39].
Vaccination protects against illness and spread. Although the US FDA and each country's Department of Health and Human Services have authorized various COVID-19 vaccines for usage, their side effects have not been thoroughly discussed [40].
Any vaccination is predicted to induce transitory side effects due to the activated immune response and the injection site tissue being traumatized. The adverse effects were classified as localized or systemic [41].
This systematic review shows the average of local side effects was Injection site pain 77.34%, considered the most often occurring local adverse effect, followed by local swelling 33.57%. According to research published in 2021 by Elnaem et al., pain at the injection site (61.1%) and fatigue (48.8 %) were the most frequently reported adverse effects among individuals who got Pfizer vaccination [42].
This review shows the average systematic side effects were fatigue 43% consider the most often occurring systemic adverse event, followed by muscle pain 39.67%, headache 33.27%, joint pain 25.75%, chills 18.34%, fever 18%, Itching 9.38%, lymph nodes swelling 7.86%, nausea 7.58%, dyspnea 7.86% and diarrhea 6.36%. These were prevalent and similar to previous research, like Alghamdi et al., noted that the most common adverse effects of the vaccination were fatigue, headache, and fever [43]. According to with manufacturer, fatigue and headaches were the second and third most often reported side reactions, occurring mainly after the second dosage [44].
Our findings indicate that most side effects are mild or moderate in severity and self-limited. Also, the incidence of serious adverse events such as anaphylactic shock or allergic response was not remarkable.
In this study, according to gender differences, the average side effects occur in females (69.8%) compared with males (30.2%). Males and females respond differently to vaccination. Biological differences, such as endocrine and sex hormones, play a significant role in females' high response to bacterial and viral vaccines [45]. Sex variations in pharmacokinetics and pharmacodynamics have also been observed, with females being more susceptible to adverse effects [46]. These effects have been attributed to females having a more significant body fat percentage than men, which affects the volume of distribution and clearance of medications [47].
Our findings show that after the second dosage, there were greater adverse effects than the first. The average side effects after the first dose were 79% and 84% after the second dose. When comparing the second and first doses of the vaccine, a study issued by the US Food and Drug Administration indicated that the incidence of local adverse effects was somewhat greater following the second dosage [44]. Abu-Hammad et al. demonstrated that adverse effects were more prevalent after the second dosage [48]. According to Elnaem et al., around 40% of adverse effects occurred more often with the second dosage, especially in those who got the Pfizer-BioNTech vaccination vs. those who received the Sinovac or AstraZeneca vaccine [42].
This research started symptoms after the vaccine of 134 participants (8.2%) had symptoms within less than an hour. In contrast, 1,140 (69.9%) had symptoms within less than 24 hours, and 297 (18.1%) patients started experiencing symptoms after vaccination on the second day. Also, about 63 (3.9%) patients developed symptoms within more than 48 hours of receiving the BNT162b2 vaccine and resolved after a few days by using analgesic medications. Alhazmi et al. found the onset of adverse effects, most notably during the first and second days, at the following times: 84% on the first day, 15% on the second day, and 1% on the third or later day [49].
According to The Centers for Disease Control and Prevention (CDC) recommendations, all vaccine recipients should be watched for at least 15 minutes after immunization, with adrenaline readily accessible at the vaccination site in case it is required. Rather than the active components, it is the inactive substances or excipients (such as egg protein, gelatin, formaldehyde, thimerosal, and neomycin) that induce allergic responses. CDC advises that persons with a history of allergy to polyethylene glycol (PEG), PEG derivatives, or polysorbate avoid both m RNA Vaccines against COVID-19. Excipients (which are added to vaccines to induce a higher immunological response, prevent bacterial contamination, and maintain the vaccine's effectiveness during transit and storage) are the primary cause of vaccine-associated specific IgE-mediated and rapid responses [50,51].
The limitations of this study are searched only in PubMed and Google Scholar databases. The absence of information on certain participant groups, such as pregnant women. Exclude RCT, Case study, and case series of this systematic review. Only English-language articles were entered in this study.

Conclusions
Our data indicate that adverse reactions to the Pfizer-BioNTech COVID-19 vaccine are common, generally mild, and self-limiting. Anaphylactic shock and severe allergic responses are rare. Local adverse effects more occur than systematic. The most often occurring local adverse effect is injection site pain and local swelling. Fatigue is the most often occurring adverse systemic event, followed by muscle pain, headache, joint pain, chills, and fever. Side effects occur more often in females than in males. These effects have been attributed to females having a more significant body fat percentage than men, which affects the volume of distribution and clearance of medications. Side effects occur more often with the second dosage than the first dose. The majority of side effects begin within 24 hours after vaccination. When the advantages of vaccination are weighed against the risks of contracting a severe COVID-19 infection or developing what seems to be largely mild to moderate short-term side effects, the benefits significantly exceed the risks. We hope that our results will reassure the public that the benefits of vaccination far exceed the risks and will help reduce vaccine hesitancy among individuals worried about vaccine safety and possible adverse effects.

Conflicts of interest:
In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.