An Examination of the Efficacy and Background of the Covid-19 Vaccine: Comparative Analysis

Introduction

The ongoing global coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus (SARS-COV-2) [1, 2]. Having been declared a global pandemic by the world health organisation (WHO) in March 2020, the pandemic has of august 2021 claimed over 4.24 Million deaths related to the illness and over 199 million positive cases reported globally. This makes it the deadliest global pandemic in the world’s history [3]. In partnership with global and national infectious diseases control organs, the WHO formulated proactive control and spread mitigation policies such as hand washing, social distancing, use of face masks, and reduced physical interactions. Although the measures have been critical in reducing the spread rates and protecting vulnerable groups such as those with underlying conditions and the elderly, they have not been effective in stopping the disease spread [1]. Some of the most virulent SARS- CoV-2 virus variants include delta, alpha, and beta variants. The long term mitigation of the pandemic has been linked to the development and roll-out of vaccines for the global population. It is estimated that with an over 60% inoculation with the Covid-19 vaccines, the world would achieve a herd immunity level allowing for the lifting of travel restrictions [4, 5]. The first mass vaccination programs kicked off in December 2020. To date, the WHO has approved at least 13 vaccines (across 4 platforms) and they have been administered globally [6].

Although the WHO undergoes a verification and vaccine testing stage, there have been challenges in the adoption of the vaccines globally. The challenges are linked to both the vaccine distribution inequality across the global regions and a negative attitude by the patients on the vaccines’ efficacy. On inequality, there has been rising outcry from the emerging and developing nations, mainly in Asia and Africa, on the shortage and challenges in accessing the vaccines due to a perceived over-ordering of the vaccines by the developed countries [7, 8]. Additionally, on the existing negative attitudes, there have been mass media and social media reports on the potential immediate short term and long term health effects from the Covid-19 vaccines inoculation. The surrounding misinformation has been linked to the low vaccine uptake in Europe and the USA developed countries. Nations such as Australia the U.K. have created mandatory policies for their essential workers to receive the vaccination as a condition of resuming to work [9, 10, 11]. There is a need to understand the vaccines’ efficacy and how the different vaccines compared and rank against each other on their efficacy levels. This is a basis for creating aura and scientifically proven data on the Covid-19 vaccinations, thus help in reducing the circulating misinformation on the vaccines globally [12].

Aim

The review investigates existing literature on the efficacy levels of the administered Covid-19 pandemic vaccines. The review examines how the efficacy levels compare or contrast among the leading vaccines globally.

Materials and Methods

The developed review is an integrated literature review. This allows for the evaluation of the existing literature and analysing and comparing the findings. The ultimate focus and aim of the review was to examine the existing vaccines efficacy levels [13]. This is through identifying the vaccines individual efficacy levels and how they compare or differ from each other. The realisation of the comparative analysis of the vaccines’ efficacy levels required the comparison of existing literature, thus adopting an integrated literature review (ILR) design. The approach applied in the review is to classify the vaccines based on the 4 platforms approved by the WHO and that are currently rolled out globally in a significant proportion. The review, based on the WHO vaccination data established that the leading vaccines with a majority of vaccinations globally were (i) Pfizer, (ii) Astra Zeneca, (iii) Johnson & Johnson, (iv) Moderna [6]. Although there are other vaccines under different stages of approval, such as the Sputnik V vaccine, the review focused on the five leading vaccines with the current highest number of vaccinations globally.

The study literature search was online and was based on five different databases. They included Scopus, Medline, Google Scholar, CINAHL, and WHO, respectively [14]. The databases were included based on their magnitude of health- related articles and the saturation of articles on the Covid-19 pandemic. The information search was developed online through the use of keywords and phrases. The review used the keywords’ Covid-19’ AND ‘vaccine’ AND ‘efficacy’ AND ‘compare’. There exists a high risk of misinformation on the vaccines and their efficacy index. Thus, the analysis focused on relying on and using only verifiable and accurate sources. The sources were predominantly limited to peer-reviewed studies, preferably the randomised control trials (RCTs), the WHO database and resources, vaccine manufactories official reports, and reliable industry and infectious diseases related literature and publications. Data published from late 2020 to the current was included [14]. All data published before the 2020 December mass vaccination roll-out was regarded as the trial and testing data on the efficacy and safety of the vaccine. Data published before the pandemic declaration as a global disaster in March 2020 was ignored as it was not related to the Covid-19 vaccination development and manufacturing process. On exclusion, all data not developed by any of the above sources were excluded from the review analysis. This also applied for all literature whose authorship was neither professional nor accredited to a reputable professional institution regarding health and infectious diseases control.

Additionally, duplicated articles, those lacking a full PDF and those not published in English, were excluded. From the searched findings and with the adoption of the inclusion and exclusion criteria, the study established 21 resources to be used in the analysis. This was from the initial search results of Scopus (103), Medline (78), Google Scholar (320), CINAHL (167), and WHO (201). The findings obtained were then analysed thematically with due reference and citation for all the information sources used in the analysis. The PRISMA figure as indicated below (Figure 1).

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Results

The initial stages of examining a vaccine efficacy are based on the development of RCTs focused on examining how effective a vaccine is in proactively protecting the vaccinated population against a virus. The RCTs and the established efficacy levels from the basis for the vaccinations approval by the respective bodies both nationally and globally. The Covid-19 pandemic was viewed as a severe global pandemic with vaccinations required urgently. Consequently, the WHO set the efficacy level at 50% for a vaccine to be listed for emergency use to inoculate against Covid-19. Although this was set as the minimum with a projected aim of at least offering 50% protection to those vaccinated, the developed vaccines, based on the RCTs and the manufacturers, indicate a higher efficacy level [15, 16, 17]. An evaluation of the obtained findings indicated that the four major vaccines globally could be classified into two main categories, namely the mRNA vaccines and the carrier/ virus vector vaccines.

Discussion

A critical analysis of the obtained findings indicates that all the examined vaccines had an efficacy index higher than the set 50% efficacy for approval by the WHO. This is a preliminary indication that the vaccines are of value to society [34]. Although an ideal efficacy would be one that allows for 100% protection, the WHO argued that due to the severity of the Covid-19 pandemic and its impacts on the society and economy globally, the offering of protection for at least 50% of the immunised population is a safe option to allowing for the reduction on the healthcare industry burden [35, 36]. Of the four examined vaccines, it is clear that the four vaccines had high efficacy in reducing hospitalisation and the risk of severe infections. One of the challenges facing global healthcare at the initial pandemic stages was the risk of overburdening the healthcare sectors globally. An analysis and case studies of nations such as Italy and France indicate the pandemic risk of hospitalisations overrunning the healthcare industry [37]. This was equally experienced in other parts globally, including the USA and Europe. One of the core challenges was bed capacities and the lack of oxygen and ventilators globally. The lack of these spaces in hospitals led to exclusive and field hospitals set up to cater to the Covid-19 pandemic [38, 39]. However, with the vaccines rollout, there has been a significant reduction in the risk of severe cases and, as such, a reduction in the need for hospitalisations. This is a significant step in ensuring that those with underlying conditions and with severe infections have enough healthcare providers, healthcare facilities, and ventilators to serve them. This is a strategic move towards realising a reduced Covid-19 mortality rate [36, 40]. The fact that a significant proportion of the inoculated population does not require hospitalisation means a lower burden on the hospitals, allowing them maximum care for those in critical and severe infection stages. Thus, despite the perceived declining efficacy in reducing mild and moderate infections, the relatively high efficacy rates for the severe infections remain a key pillar validating the vaccinations.

Furthermore, the findings indicate the need for an understanding of the full immunization process. As illustrated, the vaccines protection optimality differs based on the number of shots and the days after the shots are received. For instance, for the Pfizer vaccine, it was established that protection and efficacy was highest 12 days after the second shot while AstraZeneca efficacy was highest 15 days and later after the second vaccination [41, 42]. This means that although inoculated with the full dosage for the vaccines, and understanding is imperative on the need for care and protection to ensure that the body gradually adapts and optimises to the vaccine benefits and efficacy against Covid-19 infections. Studies and case study reports indicate that a significant proportion of infections reported among the vaccinated population occurred between the first and second doses or slightly after the second doses due to the time required for the body to optimise on the vaccine protection.

Conclusion

The review findings indicate that the existing vaccines have a significant efficacy index. The results indicate a significant risk reduction for severe infections and the need for hospitalisations. This indicates that the use of vaccines plays a key role in reducing the healthcare industry burden globally. However, a challenge exists in the perceived declining efficacy index of the vaccines with the rise in new Covid-19 virus such as the highly virulent Delta variant first reported in India and the U.K. The findings indicate the need for further studies, RCTs and real clinical reports on the efficacy of the existing vaccines against the emerging virulent variations of the disease. This would inform the future for new vaccines or the progression of the existing vaccines based on the demonstrated efficacy levels.

Conflict of Interest

There is no conflict of Interest

Funding

The review was not funded