The most severe acute respiratory syndrome coronavirus (SARS-CoV-2) mutations cause only mild harm. A small number of mutations may increase the virulence of the virus and increase host-virus interactions that are crucial to viral entry and infect. SARS-CoV-2 spike proteins mutations can have a significant effect on the behavior of viral. The spike protein is responsible for viral attachment to host cell surface receptors.
It is essential to keep track of and limit virus spread to prevent the emerging of new strains of SARS-CoV-2 which may not be able to respond to the current vaccines and medications. Despite the efforts of numerous countries around the world, mass vaccination campaigns haven’t reached the required population coverage to prevent the transmission of SARS/CoV-2.
Study: How many relevant SARS-CoV-2 variants could be expected in the near future? Image Credit: Naeblys / Shutterstock.com
Classification of SARS-CoV-2 variants
In order to effectively control the pandemic, it is vital to examine the emergence and spread of variants as well as their impact on the transmission of disease and the health of humans. The World Health Organization (WHO) has classified SARS-CoV-2 variants that pose potential risk to public health into three distinct categories: variants under monitoring (VUMs) as well as variants of interest (VOIs) and variants of concern (VOCs).
VUMs are variations that carry genetic mutations that alter characteristics of the virus. However, it’s not known what the phenotypic and the epidemiological consequences of these mutations could be. VOIs have mutations that may alter the course of disease, infectivity, and diagnostic or therapeutic escape, which could cause community transmission and pose a risk to global public health. VOCs can increase transmissibility and virulence or the severity of illness, as well as the potential to decrease the effectiveness and diagnostics, therapies and vaccines.
These variants could have to be classified differently as the virus changes over time. It is important to quantify the variety of variants that could pose a risk for public health, in order to prepare for the fight against viral epidemics.
Information about the study
A new study was recently published on the preprint server *. It used information from the WHO on the most relevant SARS CoV-2 variants. The function relies only on the number of cases worldwide since the outbreak. They allow for an accurate estimation of the number relevant variations of SARS-CoV-2 that may occur for a specific amount of infected individuals around the world. This new method can also identify the number of relevant variants per 10 million cases in any epidemiological scenario.
The team collected information on SARS-CoV-2 variants including variant characteristics that were reported by WHO the Phylogenetic Assessment of Named Global Outbreak (PANGO) and WHO classification as current relevance (VOC VUM, VOI, or VUM) dates and countries of first detection as well as the total number of cases worldwide at the end of the month in which they were detected and a cumulative count of variants. PANGO is a nomenclature system for naming and tracking genetic lines of SARS-CoV-2. This WHO data was compared numerically using the function v (N) = N/log N, where N is the constant of the numerical fitting and the value of k is 3.35 x 10-6.
“Our method is based on the WHO effectiveness in identifying the most relevant variants of SARS-CoV-2.”
Study findings
The study showed that there were nearly 44 relevant variants of SARS CoV-2 from March 2020 through November 2021. In comparison, the number of relevant variants that were newly discovered per ten million cases was 1.64 in November 2021 which was a decrease of 28.4 percent from 2.29 that was reported in March 2020.
The cumulative number of cases worldwide against the number of relevant variants of SARS/CoV-2. The dots numbered 1-10 indicate data from WHO [1, 2,] March 2020 to May 2021. The solid line represents the numerical fit U = k * N/logN obtained using Wolfram Mathematica.
The global total number of COVID-19 cases was around 252 million up to November 2021. This is roughly 43.7 relevant variants. This represents nearly 19 variants higher than what was reported by WHO in May 2021.
Conclusions
The observations in this study revealed that number of new relevant variants per ten million cases decreased very slowly with an increase in the total number of cases. As long as the virus is still present, new relevant variants of SARS-CoV-2 are likely to emerge.
The authors devised a mathematical model to calculate the relevant number of SARS-CoV-2 variants based on the global average of cases. The model only considered the relationship between the number of replications of the virus and the development of relevant variants, and left out the other factors that contribute to the spread of new variants.
It is essential to be able to predict the amount and significance of new relevant SARS/CoV-2 variants in the future. This is crucial for optimal planning of vaccination campaigns. New variants can alter viral characteristics which could have a major impact on the global control of the pandemic.
*Important notice
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
