New variants of coronavirus, particularly the Delta variant which was first identified in India last December, have been making headlines lately for being more transmissible than earlier forms of the virus.
“All viruses change over time and this virus is no different,” said Adam Brady, MD, from Samaritan Infectious Disease who heads the Coronavirus Task Force at Samaritan. “Given the high rate at which the coronavirus is replicating in the United States and around the world, it is not surprising that new variants are forming.”
How Mutations Lead to Variants
A virus can’t live on its own; it needs a host, explains Dr. Brady. Once the virus enters the body it binds to one of the host cells and starts to replicate itself inside of the cell. If it can make enough copies without being stopped by antibodies from the immune system, you get sick.
During replication the copies aren’t always perfect and sometimes there is a small mutation to the structure of the virus. Calling it a mutation sounds sinister but these changes are normal virus behavior, according to Dr. Brady. Many of these mutations make the virus less likely to cause infections, however, occasionally a mutation could enhance the ability of the virus to infect other cells. When this happens variants of interest or concern can emerge.
“Viruses mutate naturally and it often has no effect on it or makes it weaker but occasionally it becomes better at infecting cells and therefore more transmissible, like in the case of Delta,” he said.
Causes of Variants
As long as the virus can find a host, it can replicate. Any replication process can have mutations and enough mutations can lead to a variant.
“The only way to stop the variants is to reduce the transmission and the supply of hosts. That can be accomplished through vaccination or natural immunity from infection,” said Dr. Brady.
According to Dr. Brady, COVID-19 vaccination does not contribute to variants because the vaccine creates a robust immune response that targets several key parts of a virus and keep it from replicating. When the virus can’t replicate it reduces the opportunity for mutations and variants to form. (source source). While people who have been vaccinated can get and transmit COVID-19, early studies show that the amount of replication in fully vaccinated people is likely less than in people who have not been vaccinated.
Is the COVID Vaccine Effective on Variants?
So far, Dr. Brady reports the data on vaccine effectiveness on variants is very encouraging.
According to the National Institutes of Health, some of the recent mutations have occurred on a part of the virus structure called the receptor-binding site (RBS) on the spike protein. These sites control how well the virus can bind to the host and how well antibodies can bind to the virus to protect the host. The RBS aren’t the only place that affects host binding or antibodies, but it is a vital part of the virus.
“The vaccines work by producing antibodies that encircle the virus so it can’t bind to the host,” said Dr. Brady. “The mutations that led to Delta have changed how effective some of those antibodies are at the receptor-binding sites, but research has shown that the antibodies are still surrounding the virus at other sites along the spike protein and creating sufficient protection. Also, antibodies are not our immune system’s only defense against viruses. The vaccines induce strong T-cell and B-cell immunity that is long lasting and helps prevent severe infection.”
A recent study released by the Centers for Disease Control and Prevention found that even with high rates of the Delta variant, vaccine effectiveness for residents of New York was 80% against infection and more than 90% against hospitalization from COVID-19.
Also reassuring is data from the outbreak in Provincetown, Massachusetts. Despite fully vaccinated people getting infected, only four were hospitalized and none died. According to Dr. Brady, we have also seen this locally. The vast majority of our patients hospitalized with COVID-19 have been unvaccinated.
“Vaccination is effective and is the safest way to protect yourself, your family, and our community from the potentially devastating effects of COVID-19,” said Dr. Brady. “To protect yourself against variants, get vaccinated and continue to follow safety protocols like wearing a mask in public and avoiding large gatherings.”
Learn more about how to protect yourself from COVID-19.