COVID-19 Vaccines: An Overview of Different Platforms

Abstract

Vaccination is one of the key strategies to stop the COVID-19 pandemic. This review aims to evaluate the current state of vaccine development and to determine the issues that merit additional research. We conducted a literature review of the development of COVID-19 vaccines, their effectiveness, and their use in special patient groups. To date, 140 vaccines are in clinical development. Vector, RNA, subunit, and inactivated vaccines, as well as DNA vaccines, have been approved for human use. Vector vaccines have been well studied prior to the COVID-19 pandemic; however, their long-term efficacy and approaches to scaling up their production remain questionable. The main challenge for RNA vaccines is to improve their stability during production, storage, and transportation. For inactivated vaccines, the key issue is to improve their immunogenicity and effectiveness. To date, it has been shown that the immunogenicity of COVID-19 vaccines directly correlates with their clinical efficacy. In view of the constant mutation, the emerging new SARS-CoV-2 variants have been shown to be able to partially escape post-vaccination immune response; however, most vaccines remain sufficiently effective regardless of the variant of the virus. One of the promising strategies to improve the effectiveness of vaccination, which is being studied, is the use of different platforms within a single vaccination course. Despite significant progress in the development and study of COVID-19 vaccines, there are many issues that require further research.

Neutralizing Antibody Response to BBIBP-CorV in Comparison with COVID-19 Recovered, Unvaccinated Individuals in a Sample of the Pakistani Population

“…The frequency of new cases is declining currently, but WHO still considers the pandemic far from over [ 1 ]. As vaccination is one of the key strategies to ultimately halt the pandemic [ 2 ], questions related to vaccine immunogenicity and efficacy remain relevant. In many low and low–middle income countries, vaccination coverage is well below the target of 70% [ 3 ], a widely considered benchmark for herd immunity against COVID-19 [ 4 ].…”

Adrenal Crisis Secondary to COVID-19 Vaccination in a Patient With Hypopituitarism

“…Here we described clinical presentation of AC being caused by mRNA COVID-19 vaccine in patient with hypopituitarism. AC is acute life-threatening condition that contributes to the excess mortality in patients with adrenal insufficiency for which timely recognition and adequate treatment are needed ( 5 , 6 , 7 ).…”

“…ChAdOx1 SARS-CoV-2 vaccine (Astra-Zeneca) and mRNA vaccine (Pfizer/Biontech) use different mechanism with overall goal of production of viral protein to initiate immune response. While ChAdOx1 SARS-CoV-2 vaccine uses recombinant replication-deficient chimpanzee adenovirus vector to deliver genetic code of the SARS-CoV-2 spike glycoprotein, Pfizer/Biontech vaccines contain mRNA that encodes entire S protein containing immunogenic epitopes of the virus ( 4 , 7 ). This mRNA has been delivered by lipid nanoparticles to prevent quick disintegration of mRNA ( 7 ).…”

“…While ChAdOx1 SARS-CoV-2 vaccine uses recombinant replication-deficient chimpanzee adenovirus vector to deliver genetic code of the SARS-CoV-2 spike glycoprotein, Pfizer/Biontech vaccines contain mRNA that encodes entire S protein containing immunogenic epitopes of the virus ( 4 , 7 ). This mRNA has been delivered by lipid nanoparticles to prevent quick disintegration of mRNA ( 7 ). Clinical presentation written here additionally demonstrate that different types of vaccine used for a first time in humans (mRNA vaccine) can precipitate same reaction as the vaccine (ChAdOx1 SARS-CoV-2) which mechanism of action is used in prior vaccines like influenca vaccine and Middle East respiratory syndrome.…”

“…Clinical presentation written here additionally demonstrate that different types of vaccine used for a first time in humans (mRNA vaccine) can precipitate same reaction as the vaccine (ChAdOx1 SARS-CoV-2) which mechanism of action is used in prior vaccines like influenca vaccine and Middle East respiratory syndrome. Both vaccines BNT162b2 and ChAdOx1 SARS-CoV-2 have same main adverse reactions including pain, erythema and swelling at the injection site, weakness, myalgia, fever and chills ( 7 , 8 ). Major and Chacko described that AC in patient receiving T dap, pneumococcal and influence vaccine on same day was secondary to fever and gastroenteritis caused by vaccination ( 3 ).…”