Despite the growing body of research on the novel coronavirus, one question that may concern many people is whether they can get COVID-19 twice.

In this article, we take a look at the research to try to determine whether a person can get COVID-19 more than once.

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It is currently unknown whether a person develops long-term immunity after recovering from COVID-19.
Image credit: Alexander Hassenstein/Getty Images.

Anthony Fauci, MD, the Director of the National Institute of Allergy and Infectious Diseases (NIAID) and Presidential Coronavirus Task Force Advisor, believes that people who recover from COVID-19 should develop relatively robust immunity for at least a few months.

Dr. Fauci made this statement during an interview on April 8th, 2020, with JAMA editor Howard Bauchner.

Researchers and public health authorities still do not know how the human immune system responds to SARS-CoV-2 and whether or not people develop long-term immunity after recovering from COVID-19.

Fears about a possible lack of immunity arose in response to recent media reports of people testing positive for COVID-19 after previously recovering from the illness.

It is difficult to say whether these individuals tested positive as a result of a second infection. While the possibility exists, it is more likely that detectable levels of the virus remain in the body even after symptoms resolve.

The authors of a small study published in JAMA Network reported that four people tested positive 5–13 days after showing clinical signs of recovery from mild to moderate COVID-19.

In a study from the American Thoracic Society, researchers from Beijing collected throat swabs from 16 people with confirmed COVID-19.

One person had a false negative result, and half of the participants tested positive up to 8 days after their symptoms resolved.

The innate immune system fights off foreign pathogens, such as viruses and bacteria. Specialized immune cells, called B-lymphocytes or B-cells, identify proteins called antigens on the surface of invading cells.

When a B cell detects a new antigen, it causes the production of proteins, called antibodies, that bind to antigens.

Once an antibody locks onto an antigen, it attracts other cells that destroy the target.

When B cells produce a new antibody, they can continue making the same antibody if the same antigen appears in the future. This is called adaptive immunity.

Theoretically, people who get COVID-19 should develop corresponding antibodies. However, it is difficult to say at this stage how these antibodies will respond to a future infection.

Immunity offers protection that extends beyond the individual level. When sufficient individuals have developed an effective antibody response, additional benefits such as “herd immunity” become a possibility.

Herd immunity occurs when a certain percentage of a population develops immunity to an infectious disease.

Herd immunity not only protects those who are not immune, but it can also slow down and even stop the spread of infectious diseases.

A population can develop herd immunity in one of three ways:

  • The majority of the population contracts the disease and generates a corresponding immune response.
  • Many people receive inactive or weak strains of the disease through vaccination.
  • A combination of both ways above occur.

Unfortunately, herd immunity will not stop the spread of coronavirus at the moment, as researchers have yet to develop a vaccine.

Allowing the majority of the population to contract the virus could lead to hundreds of thousands of deaths.

Older individuals and those with chronic health conditions have a higher risk of developing severe, life-threatening symptoms of COVID-19.

Herd immunity may not be a safe or feasible option at the moment. However, researchers are trying to understand how the immune system reacts to SARS-CoV-2.

Fortunately, it appears that most people who contract a SARS-CoV-2 infection quickly develop antibodies.

Researchers from Shanghai released a preliminary study, which has not yet been peer-reviewed, that evaluated the antibodies levels in blood samples from 175 people who recovered from mild COVID-19 symptoms.

The majority of participants developed antibodies within 10–15 days after the onset of symptoms. However, ten participants had undetectable antibodies levels. The researchers also reported that elderly and middle-aged patients develop significantly higher concentrations of antibodies than younger individuals.

The findings of this preliminary research suggest that people can develop varying degrees of immunity to SARS-CoV-2.

People must keep in mind that this preliminary study is not peer-reviewed. The researchers behind this study evaluated a small sample of individuals with mild COVID-19. As a result, their findings may not apply to the broader global population.

Research is ongoing into the possibility of reinfection with the novel coronavirus.

Researchers and public health authorities do not know how the immune system reacts to coronavirus or whether people who recover from COVID-19 develop long-term immunity.

In the meantime, experts suggest that people continue to take preventative measures, such as physical distancing and self-quarantining, if necessary.

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