The "Omicron" mutant eludes the immune system. What does that mean?
"Omicron shows a greater ability to escape the immune system. "It is the latest variant of concern in terms of its transmissibility compared to all other variants," said Dr Maria Van Kerkhove, an epidemiologist and technical officer for combating COVID-19 at the World Health Organization, last Wednesday. The United Nations organization confirmed that the spread of new waves of "Omicron" will depend on several factors, such as the immune status of communities, the rate of vaccination against COVID-19, and the nature of the mutations that occur in the virus.
What is a mutation?
A mutation is a change in the genetic code of the COVID-19 virus. Some mutations have no effect, while others lead to changes in proteins, which can benefit the virus by making it more transmissible from person to person. The mutation may harm the virus if the immune system gains an advantage over the pathogen. The World Health Organization has detected about 540 "omicron" mutations, but only five are "under watch" for changes such as mutations or a higher prevalence rate, the Canadian Broadcasting Corporation website reported. Mutations of concern show one or more traits compared to the original or ancestral version of the virus:
It spreads more easily. It causes more severe disease. Overcoming current vaccines or treatments Doctors and scientists are watching for mutations in the virus's protein, which is used to latch onto and invade our cells. The genetic sequencing data also indicates that the more immune-evasive variants are on the increase, while the BA.5 strain that dominated in the summer is decreasing.
How does immunity work?
According to Professor of Immunology Don Bodish at McMaster University in Canada, if the virus allows our immune system to fend it off, it will be over for the microbe. To survive, Omicron variants like BQ1.1 evade our immune defences. A virus infects hosts to copy itself, using our cells as a virus factory.
But not everyone who is exposed to the virus becomes ill. The main barrier to preventing respiratory pathogens is the nose, which is supported by "mucosal immunity," which requests help from our immune system when the virus approaches.
How does the immune system defend the body?
When the Omicron mutants enter the nose and mouth through breathing, they have ways of shutting down natural antiviral immune responses. Once the virus penetrates the first layer of defence, the antibodies then work (antibodies are proteins made by the immune system to help fight infection, and they also provide protection against infection with the same virus in the future). Antibodies need to "stick" to the virus in order to be effective. Weeks after someone is vaccinated, the immune system produces lots of antibodies that provide protection.
Can COVID defeat immunity?
SARS-CoV-2, the virus that causes COVID-19, has other ways of overcoming antibody defences and is also good at hiding from them. And since the "sub-Omicron" variants evade the immune system's ability to fully control them, we are more vulnerable to re-infection now compared to previous variants, according to immunologist Dr Helen Descaloy. Descaloi explained that antibody levels are an important way to prevent transmission, but their levels also drop after the first infection.
And she continued: "If you get two doses of the vaccine and one booster, we will see an improvement in the long-term memory of infection." This happens because the body’s immune system has been exposed not only to the protein of the viral spike but also to other proteins that are important to protect us from severe diseases.
What happens when antibodies don't protect us?
The answer to this question is related to T cells, a type of white blood cell that helps protect the body from infection. When antibodies fail to fight off the virus, T cells kick into action to prevent a COVID patient from being hospitalized by targeting and destroying virus-infected cells. T cells do not prevent infection but work after the virus has penetrated.
Antibodies are made by another type of immune cell known as B cells. When the immune defences in the nose and antibodies are not effective enough to prevent infection, T cells and B cells enter the fray. One of the roles of B cells is to remember the invading virus to help create antibodies upon reinfection.