NEW COVID 19 Variants (How Concerned Should We Be?)
Genetic variants of COVID 19 are expected as viruses mutate all the time. Coronaviruses mutate slower than most RNA viruses, with an average rate of two nucleotide changes per month. A random mutation may make a virus more fit leading to an evolutionary advantage, as in what happens with natural selection, the survival of the fittest.. from the virus’s standpoint, or the mutation could have no impact on its survival. Eventually, a viral variant with an evolutionary advantage will become the dominant form of the virus. Worldwide there are twelve key clades of covid or variants of covid.
Sometimes the increased spread of a viral variant can only be attributed to chance. If a virus with a new mutation is carried by a super-spreader, moves to a new uninfected location, or is introduced to a new segment of the population, its spread rate will increase. The UK variant has become the dominant variant in multiple regions of the world, which means it’s less likely a coincidence.
NEW COVID 19 Variants|| COVID Update
Each time scientists identify a new variant. It raises the questions: does the mutation increase the viral transmission rate, cause more severe disease, and will the current vaccines or a previous infection still provide protection?
Viruses can be sloppy with their replication process. Proofreading to ensure that there are minimal errors in the genetic code takes time. Organisms usually reproduce slowly and with fewer errors or reproduce quickly and make more errors. Multiple variants of a virus with slight changes in the genetic code are then replicating in an environment that encourages the fittest survival. Viral variants that are more deadly or more transmissible win out over those with a lower ability to survive and flourish.
The only way to slow the development of new viral variants of covid is to hinder their ability to replicate. The best way to slow the replication process is vaccination. Achieving herd immunity by vaccinating 80% of the population is what will get this done.
The COVID 19 strain called B.1.1.7 identified in the UK has spread across the country, with studies out of London suggesting that the UK covid variant is 55% more infectious, which raised the reproduction rate, a measurement of how contagious an infectious disease is, to an estimated range of 1.5 to 1.7 and prompted the lockdowns in London. The reproduction rate has since decreased to around 0.8 to 1.0. The prevalence of the UK covid variant has essentially doubled, which means more infections, more hospitalizations, and deaths. Also, it means more long-haulers, the often overlooked group of people still suffering the effect of COVID 19 long after they came down with the infection.
The UK viral variant has been identified in Canada, and 20 states in the U.S. Scientists so far are not sure how the new viral variant increases its infectivity. One possibility is that people who are infected with the new variant of covid may shed more virus. Higher viral loads in the nose can increase infection risk when an infected droplet lands on your eyes, mouth, or nose. Another possibility is that the new variants of covid increase when someone may shed the virus and, therefore, are contagious.
Another possibility is that the virus is more stable in the environment. But the most likely explanation is that it binds better to the human ACE2 receptor, and so far, this is what the evidence is suggesting. In the UK, PCR tests can distinguish the old variant of covid from the B.1.1.7 variant. Mathematicians compared the death rates between those who have died from the old covid variant and those who have died from the new covid variant. This analysis led to a statement that the new covid variant, besides being more contagious, may also be more deadly.
The New and Emerging Virus Threats Advisory Group (Nervtag) says that there is a realistic possibility that the virus had become more deadly, but this was far from certain. They report that there are hints that the UK covid variant is 30% more deadly, raising the deaths per 1000 from 1% to 1.3%. Both the Pfizer and Oxford AstraZeneca vaccines are expected to work against the UK covid variant, as there is no biologically significant difference in neutralization activity, based on the evidence so far.
Mutations in the spike protein can weaken the expected antibody response after an infection with a previous variant of the SARS-CoV-2 virus or vaccination. When the immune system is first exposed to the viral antigen using either an infection or vaccination, it activates both the immune system’s arms-producing antibodies and cellular response. Memory cells are held in reserve to mount a quicker and more substantial immune response to neutralize a repeat infection.
In the laboratory, the Pfizer vaccine has demonstrated the ability to neutralize the N501Y mutation found in the UK covid variant.
Dr. Mike Hansen, MD
Internal Medicine | Pulmonary Disease | Critical Care Medicine