Mutations, variants and strains! Oh my!

While vaccinations against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), the virus that causes coronavirus disease-19 (COVID-19), proceed, news about mutations or variants of the virus is causing significant anxiety and stress. Should we be concerned? How widely have these variants spread and do they cause more severe disease? Will current treatments and recent vaccines work against them? Can they be detected with viral tests? We have many questions and unfortunately only a few definitive answers at this point. Let’s take a take a look at how and why these virus mutations occur and the status of the first variants which have been identified up to now.

How and why do viruses mutate?

The terms mutation, variant, and strain are sometimes used interchangeably; nonetheless, they’ve slight nuances (Lauring and Hodcroft, 2021). Mutation refers to an actual change within the DNA sequence of the genetic material in a wild-type or primary virus that occurred in nature. For example, in Variant of Concern (VOC) 202012/01 identified within the United Kingdom, there was a mutation within the receptor-binding domain (RBD) of the spike protein at position 501, where the amino acid asparagine (N) was replaced by tyrosine (Y) (Centers for Disease Control and Prevention [CDC], 2021a). In the D614G mutation, the amino acid aspartate (D) was replaced with glycine (G) at position 614^vol amino acid position of the spike protein. By the top of 2020, scientists had identified over 12,000 mutations within the SARS-CoV-2 genomes (Callaway, 2020). Variants seek advice from a selected region of the genome that differs between the 2 genomes. A variant is a strain that has a distinct phenotype or physical properties, corresponding to a difference in antigenicity, transmissibility, or virulence (Lauring and Hodcroft, 2021).

Basically all viruses mutate. Viruses reproduce by infecting cells and use the host to make copies of themselves. Viruses corresponding to influenza and SARS-CoV-2 encode their genomes in RNA, which generally has the next mutation rate than DNA viruses (Lauring and Hodcroft, 2021). Coronaviruses are likely to develop fewer mutations than other RNA viruses because they contain enzymes that correct a number of the errors made during replication (Callaway, 2020). The SARS-CoV-2 virus typically experiences two single-letter mutations in its genome per 30 days, which is about half as often as flu. Often, copying errors are insignificant, but when a virus infects tens of millions of individuals world wide, the likelihood increases that one in all these errors could have a critical impact, either making the virus less harmful or making it more dangerous (Hogan, 2021). A change within the SARS-CoV-2 spike protein could improve its ability to enter cells, or it could change the looks of the virus in order that previous antibodies from a previous infection or vaccine don’t recognize it.

The most vital consequences of the variants include (CDC, 2021a):

• Increased permeability and talent to spread faster
• Changed severity of the disease, either milder or more severe
• Lower detection rate with viral diagnostic tests, but most reverse transcriptase polymerase chain response (RT-PCR) tests use different targets and may detect the virus despite the presence of mutations
• Limited response to therapies and medications currently used to treat Covid-19
• Increased ability to evade natural or vaccine-induced immunity

Natural selection and adaptation may play a task in determining which variants or strains develop into dominant, corresponding to people who develop a competitive advantage corresponding to increased transmissibility or the flexibility to evade immunity (Lauring and Hodcroft, 2021). The D614G mutation within the spike glycoprotein of the SARS-CoV-2 virus, which helps the virus enter cells, was first identified in early March 2020 and spread world wide over the following month, quickly becoming the dominant strain. Scientists have found that the G mutation infects cells as much as 10 times more effectively than D viruses (Calloway, 2020). The B.1.1.7 (or 501UY.V1) lineage is one other variant that’s spreading rapidly across the southern UK and at the top of 2020 accounted for nearly 30% of all COVID-19 infections in England. According to Dr. Anthony Fauci (CNN, 2021), the one approach to prevent variants from dominating is to stop their spread by following public health guidelines and vaccinating as many individuals as possible.

Will the vaccines work against these variants?

Because vaccines and natural infection produce a response that targets multiple segments of the spike protein or the complete spike protein, the virus will need several mutations to evade natural or vaccine-induced immunity (Lauring and Hodcroft, 2021). Additionally, major vaccine manufacturers consider they may have the opportunity to switch their vaccines as needed to combat these potential variants, but this can be a lengthy and expensive process (Hogan, 2021). As of this writing, researchers have found that currently approved vaccines are in a position to recognize these variants (CDC, 2021b).

Below is a summary of the important variants which have been identified up to now.

[Reference: CDC, 2021a; World Health Organization (WHO), 2020]

We are learning more about SARS-CoV-2 variants every single day, but until we achieve widespread vaccination, individuals should proceed to practice physical distancing, practice hand hygiene, wear a mask, keep rooms well ventilated, avoid crowds, and cough right into a bent position. elbow or handkerchief (WHO, 2021).

Callaway, E. (2020, September 16). The coronavirus is mutating – does it matter? . https://www.nature.com/articles/d41586-020-02544-6

Centers for Disease Control and Prevention. (2021a, January 28). Emerging variants of SARS-CoV-2. https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/scientific-brief-emerging-variants.html

Centers for Disease Control and Prevention. (2021b, February 2). New variants of the virus causing COVID-19. https://www.cdc.gov/coronavirus/2019-ncov/transmission/variant.html

CNN (2021, February 5). Fauci says the virus variant first detected within the UK “could become dominant” within the US. https://www.cnn.com/2021/02/05/health/us-coronavirus-friday/index.html

Hogan, A. (2021, January 14). Watch: How – and why – coronaviruses mutate. . https://www.statnews.com/2021/01/14/how-coronavirus-mutates/

Lauring, A. S., & Hodcroft, E. B. (2021). Genetic variants of SARS-CoV-2 – what do they mean? , (6), 529–531. https://doi.org/10.1001/jama.2020.27124

McIntosh, K. (2021, January 26). Coronavirus disease 2019 (COVID-19): Epidemiology, virology and prevention. https://www.uptodate.com/contents/coronavirus-disease-2019-covid-19-epidemiology-virology-and-prevention

World Health Organization (2020, December 31). SARS-CoV-2 variants. https://www.who.int/csr/don/31-december-2020-sars-cov2-variants/en/