A Systematic Review on COVID-19 Vaccine Strategies, Their Effectiveness, and Issues

Abstract

COVID-19 vaccines are indispensable, with the number of cases and mortality still rising, and currently no medicines are routinely available for reducing morbidity and mortality, apart from dexamethasone, although others are being trialed and launched. To date, only a limited number of vaccines have been given emergency use authorization by the US Food and Drug Administration and the European Medicines Agency. There is a need to systematically review the existing vaccine candidates and investigate their safety, efficacy, immunogenicity, unwanted events, and limitations. The review was undertaken by searching online databases, i.e., Google Scholar, PubMed, and ScienceDirect, with finally 59 studies selected. Our findings showed several types of vaccine candidates with different strategies against SARS-CoV-2, including inactivated, mRNA-based, recombinant, and nanoparticle-based vaccines, are being developed and launched. We have compared these vaccines in terms of their efficacy, side effects, and seroconversion based on data reported in the literature. We found mRNA vaccines appeared to have better efficacy, and inactivated ones had fewer side effects and similar seroconversion in all types of vaccines. Overall, global variant surveillance and systematic tweaking of vaccines, coupled with the evaluation and administering vaccines with the same or different technology in successive doses along with homologous and heterologous prime-booster strategy, have become essential to impede the pandemic. Their effectiveness appreciably outweighs any concerns with any adverse events.

SARS-CoV-2 reinfections: Overview of efficacy and duration of natural and hybrid immunity

“…Decisions on measures against SARS-CoV-2 infections are challenging and require scientific knowledge on their efficacy and their potential benefits and harms ( Ioannidis, 2020a ; Kampf and Kulldorff, 2021 ; Pilz, 2021 ). Vaccination against SARS-CoV-2 proved to be highly efficacious in short-term randomized controlled trials (RCTs) and effective in real-life settings ( Khandker et al, 2021 ; McIntyre et al, 2022 ; Polack et al, 2020 ; Sharif et al, 2021 ). Reports on waning immunity as early as a few months after vaccination pose a challenge to public health strategies ( Chemaitelly et al, 2021b ; Goldberg et al, 2021b ; Levin et al, 2021 ; Rosenberg et al, 2022 ).…”

The Effectiveness of a Diverse COVID-19 Vaccine Portfolio and Its Impact on the Persistence of Positivity and Length of Hospital Stays: The Veneto Region’s Experience

“…RCTs also do not generally consider the use of heterologous vaccination cycles or additional doses. For all these reasons, studies on real-world scenarios are essential [14].…”

Microfluidics Technology in SARS-CoV-2 Diagnosis and Beyond: A Systematic Review

“…SARS-CoV-2 antibody detection is crucial for retrospective sero-surveillance and the assessment of vaccine efficacy [ 18 , 19 , 20 ]. Microfluidics uses different techniques to detect SARS-CoV-2 antibodies, such as the microfluidic DA-D4 (double-antigen bridging immunoassay technique, which detects total antibodies including all subclasses and isotypes) based technique developed by Heggestad et al, and sandwich/competitive immune-sensors based techniques developed by Lin et al, which reports a run capacity of 24 and three samples per device, respectively.…”

“…Current COVID-19 prevention strategies are vaccination and neutralizing antibodies, which prevent the binding of S proteins to ACE-2 receptors [ 20 , 128 , 129 ]. The clinical importance of these techniques has been debated though they remain undeniably valid.…”