By Mira Postelnek
As the COVID-19 virus continues to mutate and spread, scientists around the world are continuously tracking the changes. They are working to understand how the variants spread, how they affect public health, and whether the current vaccines will be effective against these new variants. The following article is a compilation of research from various medical journals regarding recent COVID-19 variants and contains no personal opinions on the topic.
How do variations occur?
Variants in the virus occur due to a change in the genetic material called RNA (ribonucleic acid). The coronavirus contains a spike protein that enters the cells and then copies its RNA inside the infected cell. If there is an error during the RNA copying process, the RNA changes resulting in a mutation. Mutations in the virus’ RNA give rise to various variants such as Delta and Omicron. Dr. Stuart Ray, vice chair of medicine for Data Integrity and Analytics at John Hopkins University, says, “It is the nature of RNA viruses, such as the coronavirus, to evolve and change gradually. Geographic separation tends to result in genetically distinct variants.”
How are these new variants/mutations found?
A nasal sample is obtained from an infected patient, the swab is then processed through a polymerase chain reaction (PCR) and the genetic material is extracted for testing. Next-generation sequencing (NGS) can identify new coronavirus strains without prior knowledge of the organisms. NGS will fragment the DNA into multiple pieces, add adapters, sequence the DNA fragments, and then reassemble them to form a genomic sequence. This method of sequencing can determine which variant is infecting the patient.
How do these variants differ?
A defining detail of the coronavirus is the spike protein which covers the exterior of the SARS-CoV-2. Researchers found that with differing mutations, the spike protein is affected differently. Some of the new variants seem to bind more tightly to our cells, reports Dr. Bollinger, a professor of infectious diseases. Bollinger explains, “This appears to make some of these new strains ‘stickier’ due to changes in the spike protein and therefore more easily transmitted.” These characteristic changes are why some mutations are able to spread faster than others — a higher rate of contagion results in more people infected and more illness and death. Bollinger explains that since severely ill patients from a specific mutation will die due to its severity, the virus will then have less opportunity to continue infecting others. Alternatively, as observed in the case of the Delta strain, the faster-spreading variant will infect more people, leading to numerous hospitalizations, and, unfortunately, deaths.
There have been several identified variants of the SAR-Cov-2 virus since its first outbreak in 2020. Four variants have been reported by the Centers for Disease Control and Prevention (CDC) to be present in America. The World Health Organization (WHO) recently identified a new variant named Omicron. These variants spread more rapidly due to their mutations than the original coronavirus. The Delta variant was responsible for the surge of infections in India in December 2021. The Delta strain was identified in America in March 2021 and is responsible for the majority of cases in the United States now. This variant is believed to be twice as transmittable as the Alpha variant. Although fully vaccinated individuals can still be infected by the Delta variant, infection occurs less often with less severe symptoms than for unvaccinated individuals affected by the Delta variant.
Due to multiple mutations on the spoke protein, the Omicron variant is more transmissible than the Delta variant (based on preliminary evidence). CDC expects that “[a]nyone with Omicron infection can spread the virus to others, even if they are vaccinated or don’t have symptoms.”
There is not a lot of information known about the newest Omicron variant. Scientists speculate that Omicron could cause more severe illness or death than infection with other variants if it is able to infect fully vaccinated individuals. Omicron’s potential strength to infect even vaccinated individuals is due to the multiple mutations in its spike protein. The many changes on the spike protein seemingly affect the antibody’s ability to recognize and block the virus from causing infection. The CDC still states the best way to reduce the risk of infection is through vaccines. All three vaccines provide high protection against the Delta and previous variants; however, there is no guarantee of effectiveness against new variants such as Omicron. Dr. Ray said regarding vaccines protecting against newer variants, “There is evidence from laboratory studies that some immune responses driven by current vaccines could be less effective against some of these variants. The immune response involves many components, including B cells that make antibodies and T cells that can react to infected cells. A reduction in one does not mean that the vaccines will not offer protection.” Just as the flu mutates annually, resulting in modifying the vaccine to match, the vaccine development for coronavirus can be “accommodated and changed if necessary.”
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Sources:
https://www.cdc.gov/coronavirus/2019-ncov/variants/Omicron-variant.html
https://www.mayoclinic.org/tests-procedures/covid-19-diagnostic-test/about/pac-20488900
https://www.webmd.com/lung/coronavirus-strains#1
https://healthcare.utah.edu/healthfeed/postings/2021/01/covid19-variants.php
https://www.nature.com/articles/d41586-021-03672-3