COVID-19 Update: Facts about virus mutations

Picture of Dr. Jeffrey Ebersole

Dr. Jeffrey Ebersole, associate dean for research

Feb. 5, 2021

 

COVID-19 Variants, the Pandemic, and Vaccination

We know you are inundated daily with COVID statistics, infection rates, hospitalizations, and deaths—all of which clearly demonstrate that we are still deep in the woods with this pandemic. 

Now we are hearing reports regarding variants of the original CoV-2 from the U.K., South Africa, and Brazil, as well as southern California. Our associate dean for research, Dr. Jeffrey Ebersole, shared information about this new COVID wrinkle.

First, as with any virus, the SARS-CoV-2 mutations are routine, occurring when viruses replicate. The greater the number of infected people, the better the opportunity for the virus to mutate.  Most of these mutations don't affect a virus’ ability to infect or cause disease, so they are largely unimportant. However, the variants that are of concern to the trajectory of the pandemic are those that occur in the "spike protein" of CoV-2. Virtually all of the current vaccines are directed to the spike protein for immunity, thus, changes to the spike protein are concerning when we are trying to develop population immunity through vaccination.

The spike protein of CoV-2 has 1273 amino acids, which are the building blocks that make up all proteins for viruses and humans alike.  The composition of these amino acids force the spike protein to form a specific shape of globule, which enables the CoV-2 to bind to human cells via a specific receptor called ACE2.  Most all of our cells are decorated with this receptor, however, it is highly expressed on blood vessel cells, which contributes to the virus’ broad virulence in the body. What’s more, this receptor is expressed in nasal and oral cavity cells. The virus variants receiving the "most press" at this time are those where the spike protein has changed and the globule shape now binds even better to the receptor.  This increases transmissibility, but not necessarily virulence as has been reported.

The other major concern is, will our natural antibodies developed from infection or from the existing vaccines work against these variants? The data is still being collected, but it appears that the current vaccines are effective against them, albeit potentially less efficiently.  Current examples show the Pfizer and Moderna vaccines as 95% effective against the original CoV-2 strain, but may be only 85% effective against the variants.

To put that in perspective, the annual influenza vaccine is generally estimated as 70% effective. However, Pfizer and Moderna used newer technology that will enable them to rapidly produce a 'tweaked' version of the vaccine to combat the variants.  I heard this is already in the works at these companies.

Lastly, there are many reports regarding the detection of these variants within the U.S.  The U.K. version was identified across nearly 25 states, and the South African version just recently in South Carolina. The Brazil version has not yet been detected, although it is quite similar to the South African variant.  This has led to some emphasis of travel restrictions designed to "keep these variants from coming into" the U.S. This may be a useful step in trying to control the global pandemic as vaccines are better distributed.  However, it is just as likely that the supposed U.K. and South African variants did not come from those countries at all. As I mentioned, when a virus replicates, it normally has some or even many small changes in its genome (RNA).  Thus, it seems reasonable to predict that the variants detected in our country may simply have had the same random mutations that occurred independently in the other countries. Other variants will likely occur elsewhere.

Therefore, to minimize this mutation occurrence and change the trajectory of infection in the US, we have to fundamentally limit the number of people becoming infected.  Allowing people to get infected and recover will only enhance the likelihood of more CoV-2 mutations, which could become more contagious or virulent.  The only way to stop this from occurring is through the population broadly accepting the vaccine and reaching the approximate 80% vaccinated target.

With this in mind, I encourage everyone in the UNLV Dental Medicine family to set a strong example of commitment to our patients and community by leading the effort for broad vaccination. Since accurate information and communication are paramount, I also encourage you to help educate family, friends and acquaintances regarding the importance of getting the vaccine.

Finally, while I appreciate that some individuals will decline the vaccine, the cautionary tale is that the reason for your declination will not matter to the virus.  Once infected, you provide another resource for the virus to transmit, mutate, and become more virulent.

Please do your part for all of us.