Did you know that different variants of COVID-19 can have SUB variants as well? Because the Omicron variant is now the world’s most prevalent strain, it has been able to mutate into different sub variants. The XBB sub variants stood out because they contain a high number of genetic mutations compared to other variants. These mutations or changes help the virus avoid the body’s immune response even if one has been vaccinated for COVID-19 already. Specifically the XBB. 1.5 sub variant (also known as Kraken) has a mutation that helps the virus bind to cells making it more contagious. Scientists believe that XBB. 1.5 binds “more tightly to cells in the human body that the predecessors” (Andrea Garcia). This was the dominant strain in June 2023.
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The updated COVID-19 vaccine is now being recommended by the CDC and has been approved by the FDA as of this September. It is a monovalent or single component version that specifically targets this sub variant of Omicron (XBB. 1.5). This vaccine is meant to broaden vaccine-induced immunity and provide protection from other XBB sub variants as well. This is similar to how the flu shot works in that the formula changes every year depending on which strain is spreading the most at the time. The vaccine will not prevent every version of COVID-19, however, unless there is a great change in the genetics of the virus, it should provide at least partial protection from other strains as well. The treatments for COVID-19 such as antivirals will still work against this new XBB. 1.5 sub variant.
In AP Biology, we learned about the immune system and how memory T cells and B cells are made to fight the same virus in the future. A virus enters the body through a macrophage or dendritic cell. Viral antigens are then presented on the surface of the dendritic cells or macrophages and infected cells. The viral antigen then binds to the Helper T cell and causes cytokines to be released to stimulate B cells and cytotoxic T cells. This creates a memory helper T cell. B cells divide to create plasma cells and memory B cells. The plasma cells secrete antibodies for this virus.
This process is why it is important to receive this vaccine even if one has already been infected by COVID before or if one has received the vaccine before because of the new variants such as XBB. 1.5 that are emerging. The previous COVID-19 vaccine does not necessarily protect against the XBB subvariants and having COVID-19 previously and getting those antibodies through the process described above does not mean you have the antibodies for the new strains.
I still got COVID after having the vaccine because it was a different strain of the virus than the one being targeted in the vaccine. This is very common but hopefully this vaccine means that there will be one less sub variant to worry about!
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