Individuals who recovered from a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may still carry replicating SARS-CoV-2 and be positive for SARS-CoV-2 RNA, according to findings from a research letter published in JAMA Internal Medicine.
Researchers from Università Cattolica del Sacro Cuore, Italy, recruited 176 patients who had recovered from coronavirus 2019 (COVID-19) between April 21 and June 18. These participants had 2 negative consecutive real-time polymerase chain reaction (RT-PCR) tests, had no fever for 3 consecutive days, and had a general improvement of other symptoms. Nasal/oropharyngeal swabs were tested for genomic and subgenomic SARS-CoV-2 RNA by RT-PCR and for immunoglobulin (Ig)G/IgA by serologic testing. Previously tested swabs that were positive for SARS-CoV-2 RNA were maintained at -112°F for retesting and comparisons.
Among a minority of patients (n=32), the average time between COVID-19 diagnosis and the follow-up was 48.6±13.1 days, but most patients (n=144) had a longer follow-up of 57.7±16.9 days.
A total of 32 patients (18.2%) were positive for total (genomic) SARS-CoV-2 RNA at follow-up. Among those with viral RNA, the loads ranged from 1.6×101 to 1.3×104 SARS-CoV-2 RNA copies/mL.
A single patient tested positive for replicative SARS-CoV-2 RNA. The previous oropharyngeal swab samples for all patients were positive for replicative RNA. After 2 consecutive negative RT-PCR COVID-19 tests, all but 1 patient were positive for SARS-CoV-2 serology.
The single patient who retested positive for replicating viral RNA was older with comorbid hypertension, diabetes, and cardiovascular disease. It remains unclear whether his positive replicative RNA test was caused by a recurrent infection or a reinfection. The investigators could not find evidence that he had contact with another infectious individual.
This study did not incorporate whole-genome sequencing, limiting the researchers’ ability to relate lasting RNA and serology phenotypes with specific viral strains.
These data indicate that some patients who have recovered from a COVID-19 infection may be positive for SARS-CoV-2 RNA. Further studies are needed to determine whether patients who carry replicating SARS-CoV-2 in their respiratory system after recovering from their primary illness may still be infectious.
Liotti FM, Menchinelli G, Marchetti S, et al. Assessment of SARS-CoV-2 RNA Test Results Among Patients Who Recovered From COVID-19 With Prior Negative Results. JAMA Intern Med. Published online November 12, 2020. doi: 10.1001/jamainternmed.2020.7570