Immunity to COVID-19: Can I Get It Twice?

May 13, 2020

 

In previous blogs, we covered some guidelines regarding COVID-19 and Diabetes, including the key symptoms, the various telemedicine options and extensive advice from our endocrinologist, Dr. Arna Guðmundsdóttir. In today´s blog we will investigate if those who have caught the Coronavirus can catch it again.

 

Understanding how our immune systems respond to infection with COVID-19 is key to formulating an exit strategy from the 2020 pandemic. Much of the debate about how we might begin to lift restrictions has centered around the need for a proven antibody test that looks for the presence of antibodies – specific proteins made in response to infections. Antibodies can be found in the blood of those who are tested after infection and show that they have had an immune response to the infection.

 

Here’s the question at hand:  If we were able to tell who have been infected and have recovered, and if those people could demonstrate immunity against catching the virus again, could we begin to allow them to go back to work and otherwise engage with many people? Let’s look at some of what goes into the answer.

 

Antibodies are proteins produced by the immune system to target a virus, bacterium or other pathogen. They destroy the pathogen by binding to it and making it harmless, or by flagging it for destruction by immune cells. They typically linger on in the bloodstream after an infection in case the virus returns. If it does, the immune response is much faster; patients who have recovered have resistance to reinfection. Indeed, for most viruses, the first time you catch the infection your body takes time to develop the requisite antibodies, but you should be better equipped to fight off the infection a second time.

 

Unfortunately, it might not be as simple with COVID-19. The World Health Organisation has warned that there is no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection. One recent paper looked at reinfection in rhesus macaques, who, after being infected with a standard dose of the virus, did not catch the infection a second time.

 

Dosage is important: the dose that you might receive varies depending on whether you breathed in airborne particles or, say, touched a contaminated surface and rubbed your eyes. If someone were only exposed to a small dose of the virus in the first instance, who can say how they might react if the second dose were much greater.

 

It’s unclear whether having a stronger dose response will leave you any better off. The hope is that recovered patients have developed enough COVID-19-specific antibodies to fight off a secondary infection. However, in one study on convalescent patients in China, 30% of those studied had very little or no detectable antibodies in their blood plasma.

 

The situation will undoubtedly change as new information emerges. Cities, counties, and states are rolling out widespread antibody testing to try to understand how many people have come into contact with the virus. And the further we get from initial infections, the more we’ll know about how antibody levels change over time and whether reinfection is possible.

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