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Can Mild Symptoms Provide Immunity Against COVID-19?

Recent studies conducted by scientists show evidence of a possible immunity in recovered COVID-19 patients; information stored by the human body's immune cells could help to fight off the virus again. This possible immunity may also apply to patients who developed mild symptoms of COVID-19. 

“This is exactly what you would hope for, all the pieces are there to have a totally protective immune response.” 

- Dr. Marion Pepper, an immunologist at the University of Washington and the author of a new study under review from the journal Nature

(Image is courtesy of News Medical)

How would this "immunity" work exactly?

Dr. Pepper mentions that the protection against the possibility of a relapse of infection cannot be certain until more research is done on the topic. Hypothetically, if an already-recovered patient were to encounter the virus again, the immune system would remember the virus and have the ability to prevent secondary infection.

The evidence is pointing towards recognition and the body’s natural response to fighting disease. With the COVID-19 virus, it’s hopeful that the concerns for relapse are quite low, but more studies must be conducted before coming to a firm conclusion. Some COVID-19 cases have opened up to the possibility of protective immunity; however, some ‘recovered patients’ have tested positive again. The grey area here is that it's unclear whether the virus was eliminated from the body completely or if they were actually re-infected.

Multiple other studies have been conducted as well, including one that was published by the journal Cell. The article describes how scientists were finally able to isolate the T-cells responsible for fighting off COVID-19 in patients who have fully recovered with no remaining symptoms. In the study, the virus was slowly introduced into a lab. Then, it was observed that the T-cells would send out signals and clone themselves to fight off the disease. The study shows significant promise for immune system recognition of COVID-19. Furthermore, it displays great potential for further information on a vaccine, as well as prevention of secondary infections in patients.

Ongoing uncertainty

Shih Shin-ru (施信如), director of Chang Gung University’s Research Center for Emerging Viral Infections and a member of the Central Epidemic Command Center, said that because COVID-19 has only been around for a few months, its long-term health effects and information on who would be more likely to have mild symptoms are still largely unknown. However, people of all ages and health conditions have died from COVID-19, so it seems as though the virus is not selective towards a certain demographic.

The role of antibodies in fighting COVID-19

It’s not known whether everyone who has contracted COVID-19, including those who are asymptomatic or have mild symptoms, will actually develop antibodies. In addition, it's also unclear whether those antibodies will truly protect against re-infection. If it is true, how long would these antibodies remain in the body, and how effective would they be? There are still many unknowns on the topic, and studies are continuously being conducted. Though the idea of “immunity passports” has appeared in several scientific conversations, there hasn’t been any significant progression on it. Overall, there is not enough evidence to show that people who have contracted the disease will have a lower chance of secondary infection, let alone permanent immunity. As of now, it’s too early to pinpoint the role of antibodies in COVID-19.

“We have no idea if production of antibodies during a primary infection, for example, has any role in clearing virus during that infection, or for that matter, we don’t have any good data on whether antibodies produced during an infection are protective against a second infection” 

- Taia Wang, an immunologist at Stanford University and the Chan Zuckerberg Biohub


The protection for one person may not be effective for everyone. Antibody responses can be drastically different for every person, affecting several factors including how severe the case is and whether or symptoms appear. However, understanding the way the virus functions is a crucial first step to solving additional challenges. Even now, researchers are continuing to gather data and conduct large-scale epidemiological studies that will hopefully provide a general risk assessment. These studies also aim to provide a concrete conclusion to the role of T-cells and antibodies in a possible lasting immunity.


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Article contributors: Minuki Wickramasurya, Sherilyn Wen