Everyone fears the unknown, including scientists, who up until recently were completely in the dark about the small-scale effects of the current coronavirus on the body. Why is it that some people recover much faster than others? What happens to the immune system when faced with this novel intruder?

Researchers at the Peter Doherty Institute for Infection and Immunity in Melbourne, Australia, have deciphered how cells respond to the virus, identifying that the body’s reaction isn’t as complex as first thought. The scientists studied a 47-year-old woman from Wuhan, China with a moderate coronavirus infection, who arrived into Melbourne 11 days before she developed symptoms. What they found is that the body produces large populations of several immune cells which arise when patients are recovering from a seasonal influenza infection.

How does our immune system respond to outsiders?

When the body is exposed to a pathogen, be it viral or bacterial, it starts  a protective immune response which involves recruiting specific cells to fight the intruder. These cells produce antibodies – proteins which label foreign substances (antigens) for destruction by another type of immune cell. Once the infection is cleared, the majority of these immune cells self-destruct. However a small population of so-called “memory cells” remain and can identify the pathogen again if it appears in the blood. This produces a faster immune response:  rapid production of antibodies and elimination of the pathogen before the organism gets ill. This is why you can only get certain illnesses once, as you become immune to them. This is also the basis on which vaccines work, but skipping the step where you actually become ill.

How our immune system (could) respond to COVID-19 

When analysing the blood of the patient, the scientists discovered that the antibodies recruited to fight COVID-19 are the same which appear in someone recovering from the flu. These proteins were detected in the patient’s blood days after the symptoms disappeared, indicating the body had responded  against the virus and removed it. Since this patient was otherwise healthy and a non-smoker, she did not require any other treatment. Her body was able to naturally fight off this infection by itself and attain a certain degree of immunity after the virus was eliminated.

Why does this matter?

This new information could be critical as  it may be used to predict disease severity and outcome. The results of the study indicate that someone who fails to produce an adequate immune response to COVID-19 will require heavy treatment in order to survive. On the other hand, someone with the right cells and antibodies will probably be okay with sufficient fluid intake. Of course, the researchers acknowledge this study must be repeated on a larger scale, with patients suffering from a variety of different conditions, and from different age groups and ethnicities. The problem with this virus is that it is “the unknown”, and scientists are thinking on their feet to fight this pandemic as it unfolds in front of them.

Future

The researchers are hopeful that their study will help in the race to create a vaccine for the virus. Identifying a small molecule which can induce an immune response that mimics what occurs in the body in response to COVID-19 can help set up an immune memory to fight the real infection. For this to work, scientists must monitor patients long after their recovery to establish whether the body is capable of remembering the virus in the long-term and becoming fully immune to it. If this is possible, we can prevent the infection unravelling and spreading further throughout the global population.

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