Covid-19: Understanding mutations and Delta variants

The more people infected with the virus, the more are the chances of random mutations.

By Rajneesh Bhandari

The pandemic has added words like “spike protein, delta variant, mutation etc.” to our household vocabulary, and now we have a new phrase, “Delta plus,” on the horizon.

A mutation is a change in the genome sequence of an organism. Mutations can result from genetic “copying errors” made when the organism replicates, exposure to ionizing radiation, exposure to certain chemicals, etc. Mutations cause new variations in a species, and cumulative mutations can even lead to the creation of newer species. For example, chimpanzee-like animals evolved into humans due to series of mutations over millions of years. Mutations emerge purely by chance and can be desirable or undesirable for the organism. A mutation that helps the organism better adapt to the environment is passed on to the next generation, and organisms with unwanted mutations have a reduced chance of surviving. Charles Darwin described this process as “Natural selection” in his path-breaking work “On the origin of species” in the 19th century.

New infectious diseases appear mainly as a result of chance mutations of virus/bacteria genomes. These mutations allow the virus to jump from animals to humans, overcome the human immune system, or even become resistant to antibiotics. The high mutation rates in viruses, coupled with short replication times and large numbers, allow viruses to evolve rapidly and adapt to the host environment. It is interesting to understand that the virus does not plan to mutate to escape a vaccine or a drug or become more contagious. Instead, mutations are random copying errors that happen by chance. Random mutations that allow a virus to survive better are passed on to the next generation when the virus multiplies. Many of these mutations are insignificant and don’t impact the speed of spread or severity of infection. Some mutations could even make the virus less infectious.

Influenza virus is an excellent example of how viruses change, making the virus escape natural immunity or vaccine-induced immunity. Our immune system uses surface proteins (like “spike protein”) of the virus to recognize the virus and build antibodies against the virus. Genetic mutations in influenza viruses may alter their surface proteins, making the surface of a mutated virus appear different from the original virus. When this happens, the body’s immunity from previous influenza infections no longer works against the new strains. A person then becomes vulnerable to the newer, mutated flu viruses. The old vaccines also do not provide immunity. This is why flu vaccines must be updated each year to keep up with the influenza virus as it changes.

The Covid virus is mutating relatively slowly as compared to other RNA viruses. This is due to its ability to “proofread” newly-made RNA copies of itself. This “proofreading” function does not exist in most other RNA viruses, including Influenza. Therefore, if the Covid virus keeps mutating at a relatively slow mutation rate, the vaccines will be effective for a longer time.

Pfizer and Moderna vaccines have used a novel mRNA technology that does not require a weakened or dead virus for the vaccine. The mRNA technology only needs the genetic sequence(code) of coronavirus to make the vaccine; no live virus has to be cultured and grown in labs. This new technology is like writing a software upgrade instead of finding new hardware each time. The mRNA technology platform can change and tweak the vaccines to adapt to new variants more quickly than conventional vaccines. Similarly, the yet-to-be-launched Zydus Cadila DNA vaccine will be able to upgrade the vaccine easily for new variants that emerge in the future.

The Delta variant was mainly responsible for driving the second wave of coronavirus infections and was first identified in India. It has now become the dominant strain in the UK and many other parts of the world. The World Health Organization (WHO) has categorized the Delta variant as a variant of concern (VOC) due to significantly higher transmissibility.

A study conducted by the Public Health England(PHE) has found that Pfizer and AstraZeneca (Covishield) vaccines provide only 33% protection against Delta variant after the first dose. Two weeks after the second dose, the Pfizer vaccine was 88% effective against the Delta variant, and the AstraZeneca vaccine was 60% effective against the variant. The daily new cases are rising in the UK, primarily in the younger unvaccinated and partially vaccinated population.

A new variant, Delta Plus, has recently been identified. Experts believe that Delta Plus does not appear to be more contagious than Delta. It is too early to tell if this additional mutation in the delta variant increases mortality or reduces vaccine efficacy.

The more people infected with the virus, the more are the chances of random mutations. There is a risk that one of these random mutations may turn out to be “escape mutation,” which allows the virus to slip past the natural antibodies present due to past infections and existing vaccines. Thus the faster we carry out universal vaccination, the more we can decrease the chance of “escape mutation.” It’s like getting a “Royal Flush” in the game of poker. Although the probability of getting a “Royal flush” is extremely low, but if millions of people are playing poker online, some random person may get “Royal Flush” every day somewhere across the internet.

(The author is Founder NeuroEquilibrium & Healthcare thought leader. Views expressed are personal and do not reflect the official position or policy of the Financial Express Online.)

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