Review on the Safety and Efficacy of COVID-19 Vaccines Approved in Saudi Arabia

The COVID-19 pandemic, caused by SARS-CoV-2, has resulted in millions of deaths globally, particularly among vulnerable populations. Vaccination is a crucial strategy for achieving herd immunity and controlling the pandemic. While COVID-19 vaccines have shown promise in reducing morbidity and mortality, concerns remain regarding their safety and efficacy. Several vaccines, including those from Pfizer, Moderna, AstraZeneca, and Janssen, have received emergency use authorization (EUA) from the World Health Organization (WHO). These vaccines have been shown to produce mostly mild side effects but have also been associated with rare, potentially serious adverse events such as anaphylaxis and blood clots. The safety and efficacy of these vaccines, particularly in vulnerable populations such as pregnant women, lactating mothers, children under 18, and individuals with severe illnesses, remains under investigation. This systematic review evaluates the available data on the safety and efficacy profiles of four COVID-19 vaccines approved in Saudi Arabia: AstraZeneca, Pfizer, Moderna, and Janssen, to address these concerns and contribute to informed decision-making regarding vaccination strategies.

The literature review examined studies on COVID-19 vaccine safety and efficacy, focusing on data for the four vaccines approved in Saudi Arabia. The review synthesized findings on common side effects (local and systemic), efficacy rates in diverse populations, and any reported serious adverse events. Existing research highlighted the generally mild nature of common side effects and the effectiveness of these vaccines in reducing COVID-19 infection rates, but also emphasized the necessity of continued monitoring for rare but serious adverse events.

This systematic review followed PRISMA guidelines and the methodology outlined by Khan et al. A literature search was conducted across PubMed, SCOPUS, Web of Science, and BIOSIS databases from January 2021 to September 2022 using keywords related to COVID-19 vaccines, safety, efficacy, and clinical trials. The search focused on four vaccines approved in Saudi Arabia: AstraZeneca, Pfizer, Moderna, and Janssen. Eligibility criteria included studies using human volunteers, with data on safety and efficacy including adverse reactions, dose, duration, and methodology for effectiveness determination. Studies were independently screened, first by title and abstract, then by full-text, with discrepancies resolved through discussion. Quality assessment used the Newcastle-Ottawa scale. Data extraction focused on study characteristics, population, and outcomes. A total of 360 articles were initially reviewed, leading to the inclusion of 18 studies after duplicate removal, exclusion of inadequate data and missing information. All included articles were considered of good quality based on the Newcastle-Ottawa scale (11 studies scoring 9 stars and 15 scoring 7 stars).

The review analyzed data from 18 studies on the four approved COVID-19 vaccines. The vaccines were tested on both males and females across different age groups. AstraZeneca was tested on 60.29% males and 39.7% females, Pfizer on 51.07% males and 48.9% females, Moderna on 52.22% males and 47.74% females, and Janssen on 55.14% males and 44.85% females. The age distribution varied across vaccines, with the majority of participants aged 18-65 years. Common local reactions included injection site pain (most frequent, ranging from 50.6% to 71.2% after the first dose), tenderness, swelling, and redness. These reactions generally increased after the second dose, but pain decreased with the booster dose for some vaccines. Common systemic reactions included fatigue (most frequent), fever, chills, headache, and muscle pain. Systemic reactions also generally increased after the second dose, although some (chills, headache, and muscle pain) were reduced with booster doses for some vaccines. Efficacy rates varied across vaccines and populations. The efficacy of AstraZeneca was above 70% in all tested groups. Pfizer and Moderna demonstrated efficacy above 90% in preventing COVID-19, while Janssen’s efficacy was above 68%. Efficacy was highest in individuals over 65 years of age for all vaccines. The review also noted rare and serious adverse events such as allergic reactions, blood clots, and other severe complications that have been reported, although remotely, for all four vaccines.

The findings confirm that the four COVID-19 vaccines approved in Saudi Arabia exhibit high efficacy in preventing COVID-19 infection, exceeding the WHO's minimum threshold of 60%. Common local and systemic reactions are generally mild and manageable, although some increase in severity after the second dose. The efficacy was found to be highest in individuals over 65, possibly due to increased precaution in this age group. The study highlights the importance of monitoring for rare, serious adverse events, which, while infrequent, necessitate further investigation. The different mechanisms of action (mRNA versus viral vector) across vaccines also influence their safety profiles and efficacy, underscoring the value of using various vaccine strategies.

This systematic review demonstrates that the four COVID-19 vaccines approved in Saudi Arabia provide sufficient efficacy against COVID-19 infection. While common side effects are generally manageable, rare but serious adverse events necessitate continued monitoring and further investigation. The expansion of vaccination programs necessitates ongoing data analysis to comprehensively understand vaccine safety and efficacy, particularly concerning booster dose effects and rare adverse events. Further research, potentially including challenge trials, is recommended to comprehensively assess the long-term effects and safety profiles of these vaccines, especially in vulnerable populations.

The review relies on published data, which might not fully represent the spectrum of adverse events or the experiences of all vaccinated individuals. The included studies had varying methodologies and sample sizes, potentially influencing the results. The limited data on long-term effects and the complexities of vaccine reactions across diverse populations represent limitations. Future studies should address these gaps to strengthen the evidence base.