All pathogens are capable of mutating. This is especially true of viruses capable of mutating in a short period. Mutations are alterations in genetic material (RNA/DNA) that code for proteins that coordinate the activities of organisms.
For viruses like SARS-CoV-2 (responsible for the COVID-19 pandemic), HIV, mutations are significant because they are often associated with the generation of more infective, deadlier, drug-resistant forms (variants) of the initial pathogen. These changes are weighty because they affect the approach to treatment and prevention of the disease. The SARS-CoV-2 is constantly evolving due to alterations in its code that occur during genome replication. Many variants of the COVID-19 virus have been discovered, and these variants are responsible for the different outbreaks of the disease worldwide.
Are all COVID-19 Variants More Dangerous and Infectious?
The persistence of the COVID-19 pandemic is linked to the emergence of many variants of the causative virus (Sars-Cov-2). Most of the publicly acclaimed variants of the virus are forms that can lead to a more dangerous form of the illness. World-renown health bodies like the World Health Organization and the Centre for Disease Control (CDC) have classified these significant variants into different classes. However, research shows that many mutations in the COVID-19 virus do not alter the virulence and infectivity of the original virus. A large proportion of the mutations in COVID-19 were neutral or minor changes. In addition, potentially deadly alterations in the genetic code of the COVID-19 are expunged from viral lineage.
This observation is because significant mutations in the SARS-CoV-2 genome that influence the virus’s virulence, fitness, and adaptation do not measure up to the tolerated low-effect or silent amino acid alterations. These alterations affect the Pathogenicity, infectivity, and antigenicity of the COVID-19 virus. Only a few mutations were shown to likely affect virus phenotype in a way that offers a fitness advantage.
After the advent of SARS-CoV-2 in late 2019, the virus went through an 11-month phase of relative evolutionary stability. However, since late 2020, SARS-CoV-2 evolution has been marked by the alterations that affect virus features such as contagiousness and antigenicity. These changes help the COVID-19 virus evade the immune cells and neutralizing antibodies. These alterations are most likely in reaction to the changing immunological profile of the human population.
Classification Of COVID-19 Variants
The COVID-19 virus continually changes due to mutation in its genetic material. These mutations typically result in new viral strains. The World Health Organization (WHO) constantly keep track of these mutations in COVID-19 lineage through epidemiological inquiry, virus genetic sequence-based surveillance, and laboratory research. In the fight against the pandemic, new alterations must be taken into cognizance. The emergence of variants that posed a higher risk to global public health in late 2020 prompted the classification of distinct Variants of Interest (VOIs) and Variants of Concern (VOCs) to prioritize global monitoring and research and ultimately inform the ongoing COVID-19 pandemic response. The classes of Covid Variants Include:
- Variants of Interest (VOI): variants in this class are associated with changes in receptor binding, reduced elimination by antibodies developed against previous infection or vaccination, reduced treatment efficacy, potential diagnostic impact, or projected increase in transmissibility or disease severity. Other notable features of COVID-19 variants of interest include:
- Distinct genetic markers that are expected to have an impact on transmission, diagnosis, treatment, or immune evasion
- An unusually high number of incidence or prevalence of a particular COVID-19 Variant
Presently, no COVID-19 variants are recognized as variants of interest (VOI). It is crucial that appropriate public health actions, such as increased sequence surveillance and improved epidemiological inquiry, are put in place to determine infectivity, the severity of disease, therapeutic efficacy, and whether currently approved or authorized vaccines provide protection against variants of interest.
- Variants of Concern (VOC): these variants are confirmed to have increased transmission, virulence, decreased elimination by antibodies generated during previous infection or vaccination, reduced efficacy of treatments and vaccines, and decreased detection by investigative modalities. Examples of SARS-CoV-2 variants of concerns include:
- Delta Variant (B.1.617.2): it is characterized by increased infectivity, resistance to some monoclonal antibody therapeutics, and decreased neutralization by antibodies developed after vaccination.
- Omicron Variant (B.1.1.529): It is characterized by a possible increase in infectivity and decreased neutralization by antibodies developed after vaccination and monoclonal antibody therapeutics.
- Variants Being Monitored (VBM): VBM variants include those with data indicating a possible or evident influence on authorized or permitted medical treatment. In addition, these variants are linked to more severe disease or enhanced transmission but with low or no prevalence. VBMs (variants being monitored) don’t constitute a serious or immediate threat to the population. SARS-CoV-2 Variants of Concern and Interests may be reclassified as Variants Being Monitored (VBM) when demonstrated that these variants do not pose a significant risk to public health. VBMs are continuously monitored for changes in their incidence and prevalence. A substantial change in the data of VBMs will necessitate a designation to the appropriate class. Examples of COVID-19 variants being monitored include:
- Alpha Variant (B.1.1.7)
- Beta Variant (B.1.351)
- Gamma Variant (P.1)
- Epsilon Variant (B.1.427)
- Variants of High Consequence (VOHC): Variants are designated as VOHCs if there is conclusive proof that preventative strategies or medical treatment are ineffective in curbing the disease, unlike other prevalent variants. There is presently no COVID-19 variant assigned to this class. Other essential features of Variants of High Consequence (VOHC) include:
- Diagnostic test targets that have been proven to be ineffective in the identification of the variants
- Evidence of a considerable decrease in vaccine efficiency, a disproportionately large incidence of infections among vaccinated people
- Resistance to several authorized medical treatments
- Increased hospitalizations and the severity of the clinical disease.
Identification of a Variant of High Consequence (VOHC) will necessitate notice to world health regulatory bodies (World Health Organization (WHO) and Centre for Disease Control (CDC)), who will put forward recommendations for prevention, containment of the variants, and new guidelines for treatment and vaccination.
The COVID-19 virus is continuously mutating due to changes in its genetic code. Many alterations do not significantly make the disease deadlier or more transmissible. However, Health organizations are constantly looking for genetic alterations in the SARS-CoV-2 lineage that can make the virus more infectious or dangerous. Identifying and adequately classifying these variants is cardinal to ending the COVID-19 pandemic.