Study population and setting
This is a case report of a 25-year old man residing in Reno, Nevada, USA.
Summary of Main Findings
The patient became ill on March 25, 2020 with symptoms compatible with COVID-19: sore throat, headache, cough, nausea and diarrhea. On April 18, 2020, the patient presented for care and had a nasopharyngeal swab collected which showed evidence of SARS-CoV-2 RNA. The patient reported complete resolution of symptoms on April 27 and was tested again on May 9 and May 27 by RT-PCR, and both tests were negative. On May 31, the patient reported to care with self-report of fever, headache, dizziness, cough, nausea and diarrhea. Five days later, on June 5, the patient presented again to care with hypoxia and was hospitalized; chest x-ray diagnosed atypical pneumonia, and the patient required oxygen support. A respiratory specimen collected on the day of hospitalization confirmed SARS-CoV-2 by RT-PCR, and a blood sample had evidence of IgM and IgG antibodies. The patient had no conditions or treatment that would suppress immune response. Sequence analyses of the viruses in the first and second infections suggests that they are not closely related, though both are consistent with other viruses circulating in Reno. The second infection was concurrent with a confirmed SARS-CoV-2 infection in a household member.
The authors conducted two independent sequence analysis studies to increase their confidence that the patient had been infected twice. They also conducted an analysis of samples from both infections to confirm that the person who provided them was the same, to rule out mistakes in sample labeling as a reason for the result.
There are no data presented on the immune response the patient had following the first infection, so it is impossible to determine if they developed neutralizing antibodies. This study is comprised of only one patient so the implications for this finding on risk of reinfection more broadly are unknown.
Evidence from other coronaviruses suggests that humans develop some immunity following infection but that reinfection is possible; a number of examples of reinfection with SARS-CoV-2 have now been confirmed using genetic sequencing, from Hong Kong and Europe. This is the first reported reinfection in the USA. This patient’s experience shows that the immune response from one infection with SARS-CoV-2 may not always produce sufficient protection against a second severe episode in a young person without known immune deficiencies.