The COVID-19 vaccine has been essential in flattening the curve of the pandemic, but there have been reports of various side effects derived from the vaccine. These side effects include allergic reactions, heart inflammation, and blood clotting. These symptoms have been commonly thought to be because of the patient’s immune system. But, this question as to why these immune responses to both the vaccines and responses to the virus itself have been possibly answered in a new article in The New England Journal of Medicine.

COVID-19 vaccines (2021) A

Various types of the COVID-19 Vaccine


William Murphy and Dan Longo, both Professors of Dermatology and Medicine respectively, believe that the Network Hypothesis by Niels Jerne contains insight as to why these side effects occur. In this hypothesis, Jerne details the process as to which the immune system regulates antibodies. This process is a cascade, in which the immune system launches antibody responses initially to an antigen. These antibodies can trigger an antibody response toward themselves, causing them to disappear over time. Anti-idiotype antibodies, also known as secondary antibodies, bind and deplete the initial antibody responses. They have the ability to act like the original antigen itself, which would initiate side effects to the person. 


SARS-CoV-2 spike protein, the protein responsible for binding to ACE2 Receptors

SARS-CoV-2, the virus that causes COVID-19, enters the body by binding its protein spikes to the ACE2 receptor, thus gaining entry into the cell. The immune system then reacts by producing antibodies for the virus, which neutralizes the effects of the virus. However, these antibodies can cause immune responses with the anti-idiotype antibodies. These secondary antibody responses clear the initial antibodies, which results in the depletion of the initial antibodies and a weakened efficiency for antibody production. 


Murphy states that “A fascinating aspect of the newly formed anti-idiotype antibodies is that some of their structures can be a mirror image of the original antigen and act like it is binding to the same receptors that the viral antigen binds. This binding can potentially lead to unwanted actions and pathology, particularly in the long term.” He and Longo also believe that these anti-idiotype antibodies can also target the same ACE2 receptors. 


In an article published by The Conversation, the ACE2 receptors play an important role in the immune response against SARS-CoV-2. The authors, Krishna Sriram, Paul Insel, and Rohit Loomba, write that the “SARS-CoV-2 virus binds to ACE2 – like a key being inserted into a lock – prior to entry and infection of cells. Hence, ACE2 acts as a cellular doorway – a receptor – for the virus that causes COVID-19.” Personally, this fact baffles me, since it’s truly both amazing and terrifying that non-living viruses are able to manipulate and finesse their way into infecting the host cells. 


Returning to the main article, the ACE2 receptors could be responsible for the long-lasting effects being reported to both the vaccine and the virus itself. These responses can also answer why these long-term effects can occur, even long after the infection has passed. 


These terms are apparent in our AP Biology classroom, specifically regarding the Immunity System. The immune response used to combat SARS-CoV-2 is Adaptive Immunity, which develops after exposure to pathogens including bacteria, viruses, toxins, or other foreign substances. Due to the complexity of SARS-CoV-2, Adaptive Immunity is used because it’s a specific but slower response to the virus. Both B Lymphocytes and T Lymphocytes are used in the response against COVID-19 but during different stages of the infection. When the virus first enters the body, the Immune System performs Humoral Response, in which B Cells bind to the antigen and secrete antibodies that are made by B-Plasma cells, and these antibodies are stored in the B-Memory Cells to prevent future infection. In the case that COVID-19 enters and infects a cell, the Cell-Mediated Response is used to kill off infected cells using T-Killer Cells and T-Memory Cells are created to prevent future infection.

How do you think this research will be implemented for the prevention of these long-term effects? Let me know in the comments below and stay safe!

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