SARS-CoV-2 RNA Persistence in Naso-Pharyngeal Swabs

Abstract

Since February 2020, Italy has been seriously affected by the SARS-CoV-2 pandemic. To support the National Health Care system, naso-pharyngeal/oropharyngeal swabs collected from suspected cases of Teramo province, Abruzzo region, are tested at Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise G. Caporale, for the presence of SARS-CoV-2 RNA. Out of 12,446 tested individuals, 605 returned positive results at least once, with prevalence significantly higher in men. A reduction of the level of viral RNA in the first swab per each positive patient collected over time was also observed. Moreover, 81 patients had at least one positive sample and two final negative tests: positivity in swabs lasted from 14 to 63 days, with a median value of 30 days. This shows the potential for the virus to coexist with patients for a long time, although we highlighted intermittent positivity in several cases. The evolution of the SARS-CoV-2 epidemiological situation and knowledge on viral shedding should be closely monitored, to interpret the findings correctly and adjust accordingly the surveillance activities.

Understanding viral shedding of severe acute respiratory coronavirus virus 2 (SARS-CoV-2): Review of current literature

“…Patients with severe disease have been observed to shed RNA for longer and have higher viral RNA loads at symptom onset followed by a gradual decline in viral RNA 3 weeks after symptom onset. 29,32,50,53,64,65 Based on 10 studies, the pooled median duration of viral RNA shedding from respiratory samples in patients with severe illness was 19.8 days (95% CI, 16.2-23.5) (Appendix Table 1 online). Again, significant high heterogeneity exists (I 2 = 96.42%; P < .01).…”

Epidemiological Significance of SARS-CoV-2 RNA Dynamic in Naso-Pharyngeal Swabs

“…In Italy, a total of 3809,193 million cases were confirmed (up to 16 April 2021), with 115,557 reported fatalities [2]. In order to support the national healthcare system, the Ministry of Health appointed the Istituti Zooprofilattici Sperimentali, public health veterinary institutes, to test for the presence of SARS-CoV-2 RNA, naso-pharyngeal/oropharyngeal swabs (NNS) collected from suspected human cases [3,4]. Accordingly, starting from 16 March 2020, swabs collected in the province of Teramo from Abruzzo, a central region of Italy, are regularly tested for the presence of SARS-CoV-2 RNA at the Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise (IZSAM).…”

Persistence of SARS-CoV-2 RNA in Nasopharynx, Blood, Urine and Stool of Patients with COVID 19: A Hospital-based Longitudinal Study

“…Base on The Centers for Disease Control and Prevention (CDC) guidelines, all patients with a positive respiratory RT-PCR test must be isolated until at least 24 hours with no fever, and at least 10 days from initial symptom onset [13]. However, there are several case reports on the persistence of positive RT-PCR in patients with COVID-19, indicating that individuals can remain positive after symptoms have resolved [14,15]. Therefore, the persistence of the virus in body uids can increase the potential risk of virus transmission in asymptomatic or recovered patients [15].…”

“…However, there are several case reports on the persistence of positive RT-PCR in patients with COVID-19, indicating that individuals can remain positive after symptoms have resolved [14,15]. Therefore, the persistence of the virus in body uids can increase the potential risk of virus transmission in asymptomatic or recovered patients [15]. So, it remains uncertain whether the quarantine duration, recommended by CDC is su cient to reduce transmission [16].…”