Reinfection with COVID-19

When you are ill with flu and other viruses, your body’s immune system makes antibodies to attack the virus. This means that if you are exposed to the same virus again, your body will recognise it and be ready to fight it off before you become ill. However, this does not happen with all viruses. As SARS-Cov-2, the virus that causes COVID-19, is so new, it is not yet known whether people who have been infected before would be protected from catching it again.

A new case study published in the Lancet Infectious Diseases, covers the experience of a man in the USA who caught the virus and later caught it again.

Overview of the case study

A man in the USA became ill on two separate occasions – once with mild symptoms at home and later in the year he developed more severe symptoms and was taken to hospital. He received a positive test for COVID-19 the first time in April 2020. He then had two negative tests in May 2020 while he was recovering, before a fourth test showed a positive result when he became ill again in June. He has since made a full recovery.

The authors state that when nose swabs from the patient were analysed, it was clear that the two cases of symptoms were caused by a slightly different form of the virus. This tells us that it is not a case of the virus remaining in the system before flaring up again, but instead it shows that he was reinfected.

What does the case study show us?

This study shows one example where infection with the virus did not protect this man from becoming infected again. Cases of reinfection remain incredibly rare. With over 37 million cases of COVID-19 worldwide (at time of writing October 2020), if this were common, it is likely we would have heard of many more cases. Currently, only a handful of cases have been reported.

The authors state their findings show that previous infection with COVID-19 does not guarantee total immunity for all people. They also highlight that the lack of thorough testing during the current pandemic has reduced the ability to detect possible cases of reinfection.

They conclude by stressing the importance for everyone to continue following the precautions and regulations in their country to avoid infection, whether they have previously had the virus or not.

Read the original research paper

Title: Genomic evidence for reinfection with SARS-CoV-2: a case study