Once you've had it, are you safe? Re-infection and COVID-19

Can people become re-infected with SARS-CoV-2?

There have been news reports of a female patient in Japan who was infected with COVID-19, had recovered clinically with negative tests, then 3 weeks later re-presented with symptoms and a positive test. 

With no official medical report available on this patient to clarify key missing information, what available literature is out there to guide us? 

A Chinese case report describes a 46 year old female who had a COVID-positive contact whilst visiting Wuhan, became symptomatic 4 days later (fever, cough, dyspnoea) and had classic CT findings as well as a positive SARS-CoV-2 oropharyngeal sample.  Samples taken 4 and 6 days after initial sampling (day 11 and 13 of illness) were negative and she was discharged well. Retesting 9 days from the initial sample (day 16 of illness) was positive again for SARS-CoV-2 and the patient remained well and asymptomatic. The authors suggest that convalescent patients may remain at risk of spreading COVID-19 following their illness, and that negative samples could be false negatives.  They recommend that discharged patients should quarantine for at least 14 days. 

An article by Chinese clinicians (only the abstract is available in English), reports many COVID-19 patients with recurrence of fever and positive SARS-CoV-2 tests after discharge from hospital.  The authors posit multiple reasons for this including natural disease course, secondary bacterial infections, sampling errors and reinfection (without specific reference to evidence of reinfection). 

Expert response to the news speculations about re-infection risk have been that persistent infection, relapse, or prolonged viral excretion are more likely than re-infection.  This seems in keeping with the one available case report from pubmed, which is described above. A study of two rhesus macaques who were re-exposed to SARS-CoV-2 found they did not become re-infected, however they were re-exposed just after initial infection and with the same viral strain, which may not represent the way humans will be exposed during this pandemic.

This article was written by Dr Rachel Coles, paediatric trainee, on 24th March 2020

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