New strains of the SARS-CoV-2 coronavirus that causes COVID-19 have already been identified in four different countries, including the United States. Early reports indicate that these mutations may be more contagious than the original coronavirus strain that first emerged in late 2019.
So, what does that actually mean for the future of the pandemic? And what does it mean if you’ve already been vaccinated or plan to get one of the COVID-19 vaccines? Will the current vaccines be effective against the coronavirus’ mutations? And, how can you protect yourself against future mutations?
We spoke with infectious diseases specialist and head of Internal Medicine David Tweardy, M.D., for answers.
How do viruses mutate?
In order for a viral infection to be “successful,” the virus has to bind to a human cell and have its nucleic acid (mRNA) enter inside the cell where the mRNA is replicated many times over. The enzyme that replicates the viral mRNA is brought into the cell by the virus itself.
But much as with typing a message, the results aren’t always perfect. You can make a certain number of errors in your words-per-minute rate and still be considered a pretty good typist.
Enzymes have a modest rate of “typing errors,” too, which is how mutations get incorporated into new copies of the virus. Every mistake the enzyme makes in recreating the mRNA inside a cell is technically a mutation.
Tell us about some of the new mutations in the coronavirus that causes COVID-19.
Each of the strains that has raised concerns has had multiple changes or mutations in its nucleic acid. But the mutations that are most important are those within the portion of the viral mRNA that encode the spike protein. That’s the part that sticks out from the virus, and is responsible for binding it to the surface of a cell.
Each of the variants has at least one mutation in the spike protein, as well as others elsewhere. The two most-talked-about variants from South Africa and the United Kingdom have mutations in the spike protein that make them more contagious.
When scientists talk about a mutation being more contagious, what does that really mean?
At the molecular level, it means that a variant is able to bind to the receptors on each cell a little more tightly and enter the cell more efficiently. So, a higher percentage of the cells exposed to that variant of the virus will actually become infected with the virus.
In more practical terms, it means more people can get infected by a variant, if they don’t take reasonable precautions. Because each individual infected with the mutated virus can, in turn, infect more people than someone infected with the original strain of the virus.
Existing variants appear to be able to infect the cells lining the nose between 30% and 70% more efficiently. So, instead of the original reproduction number of between 2 and 3, the more contagious variants’ reproduction numbers are likely to be between 3 and 5, or almost twice that.
That means these mutations make the coronavirus easier to catch and spread to others, making it more important than ever to mask up, wash your hands, keep social distancing and get a coronavirus vaccine, wherever it is available to you. This is especially important for immunocompromised cancer patients, who are at increased risk for severe complications if they get a COVID-19 infection.
Will the current COVID-19 vaccines work on any or all of the coronavirus mutations?
The studies I’ve seen reported in the media indicate that the antibodies generated by both the Pfizer and Moderna vaccines are able to neutralize both the United Kingdom and South African variant strains. mRNA technology makes it easy for scientists to adapt the vaccines to better respond to new mutations, if necessary. I’ve heard that Moderna may develop a booster shot that addresses these mutations, in case it’s needed.
What about the vaccines still in development that aren’t mRNA vaccines?
I have no reason to believe that any of the new vaccines in development will behave dramatically differently. These vaccinations should work just fine, in terms of protecting individuals from serious infection.
What steps should people take to protect themselves from current and future coronavirus mutations?
The longer the pandemic goes on and the more the coronavirus spreads, the more frequently it will mutate. So, whether you’ve been vaccinated yet or not, it’s important to continue wearing a mask, washing your hands and social distancing. It will take all of us doing this, and as many people as possible getting vaccinated, for us to help slow the coronavirus’ spread, so we can ultimately reach herd immunity and get back to some level of normalcy.