Review of COVID-19 Variants and COVID-19 Vaccine Efficacy: What the Clinician Should Know?

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a beta coronavirus that belongs to the Coronaviridae family. SARS-CoV-2 is an enveloped spherical-shaped virus. The ribonucleic acid (RNA) is oriented in a 5'-3'direction which makes it a positive sense RNA virus, and the RNA can be read directly as a messenger RNA. The nonstructural protein 14 (nsp14) has proofreading activity which allows the rate of mutations to stay low. A change in the genetic sequence is called a mutation. Genomes that differ from each other in genetic sequence are called variants. Variants are the result of mutations but differ from each other by one or more mutations. When a phenotypic difference is demonstrated among the variants, they are called strains. Viruses constantly change in two different ways, antigenic drift and antigenic shift. SARS-CoV-2 genome is also prone to various mutations that led to antigenic drift resulting in escape from immune recognition. The Center of Disease Control and Prevention (CDC) updates the variant strains in the different classes. The classes are variant of interest, variant of concern and variant of high consequence. The current variants included in the variant of interest by the USA are:

Acute COVID-19 Cerebellitis: A Rare Neurological Manifestation of COVID-19 Infection

“…In the era of COVID-19 variants and the new mutations of the virus, there is always a potential of atypical presentations of the COVID-19 infection [16,17]. The hesitancy around taking the widely available COVID-19 vaccinations has also contributed to the recurrent and ongoing waves of the pandemic [18][19][20].…”

Immune Responses against SARS-CoV-2—Questions and Experiences

“…Experience with the SARS-CoV-2 vaccination programmes showed that protective immunity gained by natural infection with SARS-CoV-2 is poor compared to the much higher levels of virus-neutralizing antibodies and T cells induced by the vaccines [101,102]. An emerging problem is the development of new variants of SARS-CoV-2 with the ability to escape natural and vaccine-induced immunity [103,104]. This fact prompts the need for updated vaccines [105], and confirms that a global vaccination program with high efficacy vaccines is one of the most important challenges of the next years.…”

“…Thus, current vaccines must be continuously refined to stay protective. Although the vaccines are an effective critical tool, none of them are a 100% effective in the prevention of COVID-19 illness [103]. A small percentage of the fully immunized population will show vaccine breakthrough cases.…”

“…A small percentage of the fully immunized population will show vaccine breakthrough cases. In the USA, more than 75 million people have been fully vaccinated as of 13 April 2021 since 14 December 2020 [103]. During the same duration, 5814 vaccine breakthrough cases were reported [103].…”

BNT162b2 SARS-CoV-2 Vaccination Elicits High Titers of Neutralizing Antibodies to Both B.1 and P.1 Variants in Previously Infected and Uninfected Subjects

“…Fewer and less consistent data have been obtained with the P.1 (gamma) variant. The P.1 (gamma) variant was identified for the first time in the city of Manaus, North Brazil, in December 2020 and further in passengers from Brazil tested at an airport nearby Tokyo [ 7 ]. Variant spike protein substitutions are L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, and T1027I [ 8 ].…”