As per a recent case study published in The Lancet Infectious Diseases journal the once COVID-19 exposure is not sufficient for a life-time or long term immunity, the infection can reoccur with even more severe symptoms. These interpretations came forward when a 25-year-old man, resident the US state of Nevada who was previously tested positive during the community testing event carried out on April 18, 2020, again complained about the symptoms (fever, headache, dizziness, cough, nausea, and diarrhoea) and presented to urgent care on May 31, 2020. The patient was discharged after carrying out chest x-ray.

Five days later, on June 05, 2020, he was presented to a primary care doctor where he was found hypoxic with shortness of breath. He was shifted to the emergency department after the provision of oxygen. The study was carried out on the emergency order by the Chief Medical Officer (Division of Public and Behavioral Health), State of Nevada.

The nasopharyngeal swab samples collected at the community testing event, during the period of isolation and recovery, and on presentation to the hospital were assessed. His first swab sample collected on April 18, 2020, was positive for SARS-CoV-2. After resolution of symptoms, his two test results were negative for SARS-CoV-2. On June 05, 2020, his nasopharyngeal swab was again found to be positive for SARS-CoV-2. The patient reported more severe symptoms; myalgia, cough, shortness of breath and constantly needed oxygen support in hospital. Chest radiography showed the development of patchy, bilateral, interstitial opacities suggestive of viral or atypical pneumonia. He was tested positive for IgG and IgM against SARS-CoV-2 on June 06, 2020.

Table 1: Summary of laboratory results

The case study revealed that COVID-19 reinfection could bring increased symptoms of severity. Three different mechanisms are being speculated by the researchers; first, a very high dose of the virus might have led to the reinfection and induced more severe disease, second is attributed to a more virulent form of the virus and third as antibody-dependent enhancement in which specific Fc-bearing immune cells might get infected with the virus by binding to specific antibodies.

The disease could be more severe but, the findings from the reinfection studies could be relevant for vaccine development.