Adverse Reactions of COVID-19 Vaccines: A Scoping Review of Observational Studies

Introduction

COVID-19, which has been declared a global pandemic by WHO, has already infected over 38 million people and claimed at least one million lives since the virus first emerged in late 2019 from Wuhan, China.1,2 The global infection detection rate was close to 10%, and it is estimated that 66% of people have been infected at least once as of May 2022.3 Based on these findings, the world has been dealing with a devastating COVID-19 pandemic.

A variety of campaigns and actions are being undertaken to combat this pandemic, beginning with the establishment of local lockdowns and mass testing.4,5 Furthermore, as a new promising way, COVID-19 vaccine can be called hope to reduce the mortality rate of infected individuals and return to some forms of normal life.6 The United States has approved the use of two COVID-19 vaccines, Pfizer-BioNTech and Moderna COVID-19 vaccines, both of which are to be administered in a two-dose sequence. Following Phase III clinical trials in ten countries worldwide, China and a few other countries approved the Sinopharm COVID-19 vaccine.7 Because these vaccines were modeled using various processes and approaches, they differ in some aspects such as efficacy and storage conditions.8

The side effects of the COVID-19 vaccine were reported by 50% to 90% of participants in randomized clinical trials of COVID-19 vaccines.9 Another study conducted worldwide (US, Argentina, Brazil, South Africa, Germany, and Turkey) showed that more than 30% of participants had side effects.10 Clinical trials conducted in Argentina, Brazil, Chile, Colombia, Mexico, Peru, South Africa, and the United States showed that the majority of participants had both local and systemic reactions to the COVID-19 vaccine.11 Based on clinical trials, COVID-19 vaccines were found to be extremely safe;9,10 however, there is less evidence comparing the safety of these vaccines in real-world settings.

Vaccine production is a difficult and lengthy. Rather than treating sick people, vaccines are given to large groups of healthy people to prevent sickness. Thus, the protection barrier for a new vaccination must be high and apply to the whole target population, regardless of age, gender, color, or ethnicity.8 Some people may refuse to receive a vaccine due to potential side effects, while others may be apprehensive about adverse reactions due to allergies or comorbid diseases.12 As a result, vaccine research and testing methodologies must be led carefully and deliberately by a primary focus on protection.

To date, no vaccine can be claimed to be completely free of adverse reactions, but the majority of them are either preventable or treatable.13 In some vaccines, early side effects such as fever, pain, myalgias, headaches, and local or injection site effects are related to immune surge.14 The adverse reactions to the COVID-19 vaccine are critical to public trust in the vaccination. The rates of vaccine hesitancy and rejection are still high, which is associated with more negative beliefs that the vaccination will cause adverse reactions;15 was found as the most significant potential barriers to getting vaccinated against COVID-19.16 Adverse reactions were the most important factors in individuals’ vaccine choice decisions.17 Aside from that, the possibility of a serious adverse reaction was discovered to be a variable cause of vaccination rejection.18

Therefore understanding the adverse effects will aid in increasing the vaccine’s success rate. The majority of studies on vaccination adverse effects focused on clinical trials or pre-and post-intervention, with only a few focusing observational studies, particularly those that examined the impact of vaccine on daily living in a real-world environment. As a result, the aim of this study was to do analyze the adverse reactions to COVID-19 vaccines that have been reported in a number of observational studies.

Materials and Methods Study Design

The current review was written using the Joanna Briggs Institute’s scoping review method (JBI).19 The concept of interest was the challenges to discover the adverse reactions of the COVID-19 vaccines especially that using the observational studies. We included only an observational quantitative study designs as most of the review were on clinical trials and pre-and post-intervention.20,21 Observational studies has benefit for document the effects of naturally exposed outcomes, which in this case are any outcomes produced by an intervention or treatment that were not originally intended by the person who prescribed the intervention.22 This scoping review protocol was following the PRISMA-P guidelines.23

Search Strategy

On June 2022, we conducted initial research using all identifier keywords and relevant terms in the electronic databases PubMed, Science Direct, and CINAHL. The search strategy for all databases was the same as shown in the PRISMA Flowchart (Appendix I). In the search, keywords with Boolean operators (“OR” and “AND”) related to process development and trigger tool validation were used (Table 1). We did not search the grey literature because we are only interested in studies published in peer-reviewed journals that are based on scientific methods that use evidence to develop conclusions.

Table 1 Search Terms

Eligibility Criteria and Data Selection

The inclusion criteria were observational studies that clearly described the adverse reactions to COVID-19 vaccines published in English between January 2020 and June 2022. Furthermore, studies were included if the outcome of the adverse reactions was defined objectively such as the impact on daily life or the severity of the reactions. Two reviewers assessed the eligibility of all studies (ID, AAS). Any conflicts or disagreements were handled and resolved by the third reviewer (AA).

Data Extraction and Synthesis

Relevant data were extracted from the included studies to answer the review question using the JBI methodology.19 The authors’ names, publication year, country of origin of the study, and characteristics (aim of study, vaccine types, population, study design, adverse reaction, impact) were all retrieved (Table 2). To map the included research, we extracted the key findings of the studies into the COVID-19’s adverse reaction. We also extracted the measured outcomes of COVID-19 vaccine from all eleven studies.

Table 2 Summary Table of Adverse Reactions of COVID-19 Vaccines

Results

The initial search yielded 400 articles using the keywords in three databases. Mendeley Reference Manager identified duplicates automatically, resulting in a total of 320 articles being evaluated and those that did not fulfill the inclusion requirements being excluded. Eligibility was determined for a total of 55 full-text articles. Thirty-one publications were deleted because they were not observational studies, and another 13 were excluded because the outcome did not include adverse reactions to COVID-19 vaccinations. Finally, eleven articles were chosen after passing the eligibility criteria. Appendix 1 depicts the entire study flow (Appendix).

Study Characteristics

All of the research employed the observational study design. The 11 studies were undertaken the United States, the United Kingdom, Canada, Peru, the United Arab Emirates, and South Korea and most of the studies taking place in developed countries.24–34 The majority of the studies had similar contexts, but the populations varied and were conducted in general community populations, with the remainder conducted in healthcare professionals, armed forces personnel, and patients with systemic lupus and cancer. The objectives of most of the studies were to investigate the adverse reactions after those populations vaccinated with COVID-19 vaccines.

Types of Adverse Reactions

Adverse reactions are classified into two types: vaccine-related events and allergic reactions. The majority of research has been on negative vaccination reactions, and also no allergic reactions. The most commonly reported COVID-19 vaccine-related adverse reactions include local injection and systemic side effects. Joint or muscle pain, tenderness, itching, and paresthesia in the injection site.24–28,31,34 Local effects were also greater in previously infected individuals than in those who had never been infected. Fever, chills, fatigue, headache, nausea, myalgia, pyrexia, and dyspnea are among the systemic side effects.24–29,31–34 Some cardiovascular side effects like sinus tachycardia, premature ventricular contractions, and right bundle branch block may occur.33 The vast majority of patients who reported unfavorable cardiovascular events were men. Males reported more unfavorable effects than females, such as chest pain or discomfort, dyspnea and palpitation.33

Everyone in the community; health workers, students, and cancer or systemic lupus patients had the same adverse reactions based on the data. The adverse responses seen by participants following the first dose of COVID-19 vaccinations are modest, with local pain and fever, according to the studies included.24–34 Another study, on the other hand, discovered that moderate to severe reactogenicity was more typically observed after immunization dose two.27 These side effects were more common after the second dose than after the first.29,31 Patients who visited the ER for cardiovascular adverse events, on the other hand, did so more frequently after the first vaccine dose than after the second.33 Some deaths were also reported, however an examination of death certificates found that the most common reasons of death were heart disease and COVID-19.27

Type of Vaccine Associated with Adverse Reactions

This study included reports indicating the type of vaccine used was linked to adverse reactions among participants. Types of vaccines included in this study are Pfizer-BioNTech, Oxford-AstraZeneca, Sinopharm, and Moderna.24–34 According to the studies, the type of vaccine given was connected to adverse reactions among participants. Side effects are 2.9 times more prevalent in first-time Sinopharm vaccination recipients.26 However, Pfizer-BioNTech vaccination recipients were 1.4 times more likely to suffer an adverse reaction following the second dosage.26 According to Sinopharm vaccine recipients, people with connected comorbidities had a statistically significant higher percentage of adverse effects than others.26 According to Pfizer-BioNTech vaccine recipients, individuals having a history of past infection with COVID-19 reported a statistically significant higher percentage of adverse effects than the others.24,26

Dyspnea, death, pyrexia, tiredness, and headache were the most prevalent serious reports of Pfizer-BioNTech.27,29 Another study found that the majority of Pfizer-BioNTech users have mild-to-moderate negative effects.30 Side effects of the Oxford-AstraZeneca (ChAdOx1 nCoV-19) vaccinations include fatigue, headache, tenderness, local discomfort, myalgia, fever, asthenia, induration, and allergic skin.24,25,28 Local effects were observed less frequently after the second dosage of both vaccines than after the first dose, as was the case with Pfizer-BioNTech.24,28

Moderna, another mRNA vaccine, had similar adverse effects as Oxford-AstraZeneca (ChAdOx1 nCoV-19), including headache, asthenia, and myalgia.25 However, no participant experienced serious local or systemic reactions after receiving both mRNA vaccines, chadOx1-ncov-19 (astraZeneca) and Moderna.25 Another study revealed that persons who received Moderna vaccinations (who had heart disease and COVID-19) had serious outcomes, such as fatalities.27 The majority of BNT162b2 [Pfizer-BioNTech] and mRNA-1273 [Moderna] mRNA vaccination patients experienced cardiovascular-adverse responses within 7 days of receiving both the first and second doses.33

Impact of the Adverse Reactions

We looked at the severity of the reactions or the impact of adverse reactions on daily life as vaccination side effects can impair one’s capacity to conduct daily tasks. The majority of the reactions were mild to moderate in nature and did not affecting daily tasks,27 appearing within 1–2 days following vaccination and dissipating within a few days. On the first day following vaccination, the impact of mRNA vaccination, BNT162b2 [Pfizer-BioNTech] and mRNA-1273 [Moderna], on everyday life activities was most often reported among vaccine recipients.27 60% of Pfizer vaccination participants experienced moderate side effects, and 75% felt the vaccine had little influence on their regular lives.29 Another study described the effect of vaccines on work and daily life for participants who had received ChAdOx1 and BNT162b2 COVID-19, with the majority of adverse effects occurring within 24 hours of vaccination, with varying duration of symptoms, and approximately half indicating that they were impacted for more than 24 hours.34 Women were more likely than males to experience moderate-to-severe side effects that interfered with their daily activities. However, the majority of individuals, regardless of gender, reported that the COVID-19 vaccine had no effect on their everyday activities and that any adverse effects were minor.29

Discussion

Several adverse reactions to COVID-19 vaccines have been identified in this review. Local and systemic side effects are among the most common adverse reactions to all COVID-19 vaccines, as previously stated in the studies included. Local side effects includes joint or muscle pain tenderness, itching, induration and paresthesia in the injection site.24–28,30,31 Meanwhile fever, chills, fatigue, headache, nausea, myalgia, pyrexia, and dyspnea are among the systemic side effects.24–29,31–34 Local and systemic adverse events occurred within 7 days of receiving COVID-19 vaccines, with fever, fatigue, and headache being the most common systemic adverse reactions.35 This finding is consistent with other study that confirmed the incidence rate of frequent adverse effects among healthcare workers was 32.1% for fever, 69.1% for muscle ache, and 48.7% for headache.36 While injection-site pain was the most common local adverse effect.37

Other adverse reactions previously mentioned were allergic, such as skin burning, rashes, and red welts on the lips and face also cardiovascular adverse reactions.24,31,33 Severe allergic reactions following COVID-19 vaccination are extremely rare, but have garnered attention due to potentially fatal outcomes and a high level of uncertainty.38 Other research indicates that cardiovascular side effects such as tachycardia, flushing, hypertension, hypotension, and peripheral coldness have also been reported.39 Other studies found that people who received the Pfizer/BioNTech vaccine had a higher rate of cardiovascular adverse events than people who received other types of vaccines.39 However, all reported adverse events were mostly mild, and did not following by hospital admission.

Vaccine type and dose were also linked to different patterns of interference with work and daily life.34 There were fewer adverse reactions reported after the second dose of ChAdOx1 vaccination than after the first dose, and the effects on daily life and work were minor.34 Another form of COVID-19 vaccine linked to mild or moderate severity adverse effects reported following Moderna vaccination, with no influence or interference in work-life activities.40 Another study discovered that 79.7% of health workers who were immunized with the BNT162b2 mRNA vaccine were able to return to work.41

Previous study backs up our findings that COVID-19 vaccination adverse responses are modest and have no effect on the recipient’s everyday life.41 This finding is also supported by another study which described the efficacy of vaccines ranged from 60% to 90% which are always efficient against asymptomatic (SARS-CoV-2) infection, symptomatic COVID-19, COVID-19 hospitalization, severe or critical hospitalization, and death.42 Deaths following COVID-19 vaccination, as reported in one study, have no connection to the vaccine, but rather to heart disease or COVID-19. The issue of excess death from COVID-19 immunization is a scientifically challenging matter that is influenced by the type of vaccines used, the age and health condition of the vaccinated population.43 It can be interpreted that host immunity and the type of vaccine are known to influence COVID-19 vaccine adverse responses.

Inconsistencies in adverse reactions may also be caused by symptoms connected with culture or languages.34 The majority of studies were conducted in developed countries where citizens have a greater understanding and awareness of vaccine adverse reactions therefore the adverse event reporting rate might be higher. Whereas the public may be perplexed by the disparities in results, which are dependent on the research design and subject studies. Therefore, as recommendation, it is critical to disseminate clear information to the public, about vaccine side effects, potential adverse reactions, and safety level of the vaccines provided. Multi-strategies at individual, organization and population level need to be employed to reduce vaccine hesitancy.

There are various limitations to this study. First, this analysis only gathered evidence from observational studies, which are prone to biases such as confounding, information, and selection bias. Observational studies, on the other hand, aid in finding adverse events or negative effects that demand a longer time of follow-up. Second, due to the limitations of the keywords and database, the findings may not have captured all of the evidence in the literature; however, this study did aid in mapping the available evidence in observational studies.

Conclusion

This study confirmed prior findings that the COVID-19 immunization caused mostly mild or non-severe side effects. This review discovered some adverse reactions to COVID-19 vaccinations with most prevalent adverse reactions to all COVID-19 vaccinations are local and systemic side effects. Other previously cited side events included allergic responses and cardiovascular problems. The type of vaccine and dose were linked to the various adverse reaction patterns. Individual daily activities are not severely influenced or interfered with. Deaths following COVID-19 vaccination have nothing to do with the vaccine, but rather with heart disease or COVID-19. It is critical to give the public with accurate information on vaccine side effects, probable adverse reactions, and the safety level of the vaccines provided. To reduce vaccine hesitancy, multiple measures must be implemented at the individual, organizational, and population levels. Future research could look into the impact of the vaccine on patients of various ages and medical conditions.

Acknowledgments

The authors would like to express their gratitude to the Indonesia Research Collaboration scheme.

Disclosure

The authors report no conflicts of interest in this work.

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