We report here two cases of healthy adults who had two episodes of possible COVID-19 infection. Interestingly, in one case, the symptomatic patient with recurrence of positive SARS-CoV-2 occurred after three months of the initial infection that did not trigger a protective immune response. In the other case, asymptomatic patient with recurrence of positive SARS-CoV-2 occurred within three months of the initial infection.
Recently, Yao et al. demonstrated that SARS-CoV-2 viral particles remain in previously positive patients’ lungs whose NP swabs results were negative three times consecutively; this suggests that SARS-CoV-2 virus may not be eliminated when the symptoms disappear . Therefore, there is still a reason to be cautious, and we need to be aware of recovered patients and their potential infectivity. Interestingly, there have not been any studies demonstrating that recovered patients are infectious.
To our knowledge, our cases are the first to describe positive SARS-CoV-2 viral RNA in recovered COVID-19 patients in the Middle East. According to the Centers for Disease Control and Prevention (CDC), reinfection of SARS-CoV-2 is highly considered in a patient who becomes symptomatic around 90 days after onset of infection and has been in close contact with an infected person, supporting our first case . A similar case presenting recurrence of SARS-CoV-2 has been reported in Hong Kong, bringing more attention lately. To and his colleagues demonstrated that second episode of asymptomatic infection occurred after the first symptomatic episode in an apparently immunocompetent patient . In addition, they confirmed SARS-CoV-2 reinfection by performing whole genome sequencing for the first and second episodes indicating different clades . We assume that the recurrence of COVID-19 is possible due to the presence of nonprotective IgG and recovered patients might be carriers and actively transmitting the virus even after their two negative tests [10, 11]. Thus, gatherings of positive cases are not safe, and there should be an emphasis upon such social practices, and for those in convalescence, we suggest that they undergo regular tests for infectivity assessments.
The presence of SARS-CoV-2 virus appears to be unstable because of the possibility of false-negative results of the molecular test which might be due to fluctuations in the viral load or pre-analytical errors during the sample collection . In our case reports, reducing the chance of false-negative and false-positive results was done by confirming each test result in different laboratory with new NP swab collection. For both cases, first positive test results were confirmed by the NHL, and two consecutive negative tests were done before the patients were considered to be cured. Although these are only two case reports and the evidence is not determinant, it gives insight and encourages future cohort studies.
In conclusion, the global public health is at risk of the possibility of recurrence of SARS-CoV-2 as we exhibited in our case reports, which could contribute to the spread of the virus. Therefore, additional virologic, immunological, and epidemiological studies should be done to have better understanding of SARS-CoV-2 recurrence mechanism.