Coronavirus is the latest addition to the list of deadly infections for humans and also, humanity’s current greatest challenge. What makes the virus more dangerous its mysterious nature. Every time scientists think that we are close to knowing everything about the virus, a new variant of the infection takes the healthcare industry by storm. This gives rise to one of the most significant questions- after a person is infected with COVID-19, is it possible to get it again?
The straight answer to the question if you can get COVID again is yes. You can.
YES. You Can Get COVID Twice
As per researchers in Hong Kong on August 24, 2020, people can get reinfected with COVID-19 twice even after getting infected with COVID-19.
There is not enough evidence in favor of it, however, there are plenty of examples and cases in real life where people were reinfected with COVID-19.
A living example of such a case is a 33 years old man in Hong Kong who was infected with coronavirus once in March. He was tested positive after suffering from cough, sore throat, fever, and headache continuously for 3 days. He remained admitted to the hospital until he was tested negative twice.
After 4 months, on August 15, the man returned to Hong Kong from a vacation to Spain and the U.K, the areas with the resurgence of COVID-19 cases. At the airport, a sample of his saliva was taken for COVID-19 testing, and the result was positive. But this time, he had such symptoms and was taken to the hospital for monitoring. His report says the amount of virus he had in his body decreased with time, stating that his immune system was defending the infection independently.
The doctors examined the virus that infected him each time and realized that the genome of the virus was the cause of the reinfection. Both the phases were different because the virus mutated(changed) in 4 months of getting infected. This live example made scientists conclude that COVID-19 can infect your immune system again.
Are You Immune To COVID-19 If You Get It Once?
The human immune system is the defense against foreign particles and infection, which are categorized into two types.
The first is always ready to go and jumps into action as soon as any foreign particle is detected inside the body. The innate immune response includes the release of chemicals, causing inflammation and white blood cells that can destroy infected cells.
The human body responds to such viral infection immediately with a nonspecific innate response with macrophages, neutrophils, and dendritic cells that slow down the progress of spreading the virus and prevents symptoms from occurring.
But this part of the immune system is not specific enough to fight against coronavirus; neither does it provide immunity to the COVID-19. It only binds the coronavirus with the help of proteins known as immunoglobulins.
After such a nonspecific response, the body produces T-cells that help to recognize and eliminate other coronavirus infected cells. This is known as cellular immunity. The combination of nonspecific response(immunoglobulins) and cellular immunity can together help your body to fight against the coronavirus preventing the body from reinfecting.
In case the infection is very severe, the combination of these will help you prevent severe illness or reinfection. Such responses are usually measured with the help of measuring the presence of antibodies in the blood.
Usually, the production of antibodies takes time to target the coronavirus infection, such as 10 days. As per the researchers, the sickest patients will develop the strongest immunity. If the adaptive immune response is strong enough in producing antibodies, it will leave a long-lasting memory(impression) of the infection that will give protection in the coming future.
The unknown fact is, researchers, don’t know the specific severity of the infection that will help a person to develop a sufficient amount of adaptive immune response to fight against COVID-19. Some people get COVID-19 again even after having a severe infection. So how much severity will be needed to develop a strong adaptive immune system? This is the unknown part.
How Long Does Immunity Last?
The human immune system’s memory is similar to ours. It remembers some infections very clearly, but also has a habit of forgetting others. For example, Measles is a highly memorable infection to the human immune system; one bout gives life-long immunity. Consequently, a weakened version of the MMR vaccine is provided to fight against the infection.
However, many other infections are forgettable to the immune system, such as children can get infected with RSV (respiratory syncytial virus) multiple times in the same winter season.
Coming back to COVID-19, the SARS-Cov-2 virus has not been around long enough to determine whether the immune system will remember the virus or not. If it does, how long will it remember the virus? Does this remembrance of the virus for the human immune system depends on other parameters(severity) or not?
All these doubts are still not cleared by the researchers. Therefore, it is not yet clear about getting reinfection from the coronavirus.
Are There Any Other Ways?
Six other human coronaviruses can help us get only an idea about the antibodies and reinfection.
Four of the coronaviruses show symptoms of the common cold and immunity for a short period of time but can be reinfected within a year.
As the research at King’s College London also suggested, levels of antibodies that kill coronavirus diminish throughout the three-month study. This means after this period, people might get reinfected.
On the other hand, even if these antibodies disappear, cells present in our body manufacture those antibodies to fight against the virus, called B cells. These cells will still be around to look after the infection or any foreign intruders.
These B cells remain in the body for a longer period of time, just like the Spanish flu case. In such cases, B cells have been found in people 90 years after that pandemic.
If this is true and the same goes for COVID-19, the coronavirus’s reinfection would be milder than the first. Like the case of a 33-year-old Hong Kong man infected again by the COVID-19 but without any severe symptoms.
Still, there are many unanswered questions left. What happens to T-cells? It is not clear what happens to them in the long term. But these cells that fight against the original Sars (Severe Acute Respiratory Syndrome) have been found 17 years later.