Corrigendum to "Presymptomatic viral shedding and infective ability of SARS-CoV-2; a case report" [Heliyon 7, (2), (February 2021), Article e06328].

[This corrects the article DOI: 10.1016/j.heliyon.2021.e06328.].

Detection and isolation of airborne SARS-CoV-2 in a hospital setting.

Transmission mechanisms for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are incompletely understood. In particular, aerosol transmission remains unclear, with viral detection in air and demonstration of its infection potential being actively investigated. To this end, we employed a novel electrostatic collector to sample air from rooms occupied by COVID-19 patients in a major Swedish hospital. Electrostatic air sampling in conjunction with extraction-free, reverse-transcriptase polymerase chain reaction (hid-RT-PCR) enabled detection of SARS-CoV-2 in air from patient rooms (9/22; 41%) and adjoining anterooms (10/22; 45%). Detection with hid-RT-PCR was concomitant with viral RNA presence on the surface of exhaust ventilation channels in patients and anterooms more than 2 m from the COVID-19 patient. Importantly, it was possible to detect active SARS-CoV-2 particles from room air, with a total of 496 plaque-forming units (PFUs) being isolated, establishing the presence of infectious, airborne SARS-CoV-2 in rooms occupied by COVID-19 patients. Our results support circulation of SARS-CoV-2 via aerosols and urge the revision of existing infection control frameworks to include airborne transmission.

Civil-Military Collaboration to Facilitate Rapid Deployment of a Mobile Laboratory in Early Response to COVID-19: A High-Readiness Exercise.

Rapid and adaptable diagnostic capabilities are of great importance in the face of emerging infectious diseases. In an outbreak, timely establishment of diagnostic routines is crucial to identifying cases and preventing the spread of the disease, especially when faced with high-consequence pathogens. In this article, we describe a multiagency exercise including the rapid deployment and diagnostic adaptation of the Swedish Armed Forces mobile laboratory (biological field analysis laboratory) in the context of COVID-19. This deployment was initiated as a high-readiness exercise at the end of January 2020, when the global development of the outbreak was still uncertain. Through collaboration with the Public Health Agency of Sweden and a civilian hospital, a real-time reverse transcriptase polymerase chain reaction method specific to SARS-CoV-2 was made available and adapted to the mobile laboratory, and the team established and evaluated a functional and efficient diagnostic asset along with a logistical support chain. We also organized and evaluated mobile testing teams, and the method was later used in large-scale, national, cross-sectional COVID-19 surveys in several regions of Sweden. In this article, we focus on the challenges of overbridging the civil-military interface in this context and identifying lessons learned and added values to the response during the early pandemic. We propose that the experiences from this exercise and governmental agency collaboration are valuable in preparation for future outbreaks.

Presymptomatic viral shedding and infective ability of SARS-CoV-2; a case report.

Possible pre- or asymptomatic transmission has been reported, both from SARS-CoV and from MERS-CoV outbreaks, although this appears to be uncommon. In contrast, during the COVID-19 pandemic, an increasing number of studies and case reports indicate that pre- or asymptomatic transmission of SARS-CoV-2 is not only possible but also occurs frequently. We report repeated rRT-PCR detection of SARS-CoV-2 in a health care worker and demonstrate infective ability up to three days prior to mild COVID-19 symptoms. rRT-PCR indicated high viral levels approximately three days after exposure. Viral samples collected one and three days prior to symptoms exhibited infectivity on Vero E6 cells, confirmed by detection of double-stranded RNA by immunofluorescence, assessment of cytopathic effect (CPE) and rRT-PCR. SARS-CoV-2 specific IgM and IgG antibodies were detected by day 9 and 15, respectively, after symptom onset. We propose that this provides evidence for potential early presymptomatic transmission of SARS-CoV-2 and that infectivity may be manifest shortly after exposure.

Long-distance airborne dispersal of SARS-CoV-2 in COVID-19 wards.

Evidence suggests that SARS-CoV-2, as well as other coronaviruses, can be dispersed and potentially transmitted by aerosols directly or via ventilation systems. We therefore investigated ventilation openings in one COVID-19 ward and central ducts that expel indoor air from three COVID-19 wards at Uppsala University Hospital, Sweden, during April and May 2020. Swab samples were taken from individual ceiling ventilation openings and surfaces in central ducts. Samples were subsequently subjected to rRT-PCR targeting the N and E genes of SARS-CoV-2. Central ventilation HEPA filters, located several stories above the wards, were removed and portions analyzed in the same manner. In two subsequent samplings, SARS-CoV-2 N and E genes were detected in seven and four out of 19 room vents, respectively. Central ventilation HEPA exhaust filters from the ward were found positive for both genes in three samples. Corresponding filters from two other, adjacent COVID-19 wards were also found positive. Infective ability of the samples was assessed by inoculation of susceptible cell cultures but could not be determined in these experiments. Detection of SARS-CoV-2 in central ventilation systems, distant from patient areas, indicate that virus can be transported long distances and that droplet transmission alone cannot reasonably explain this, especially considering the relatively low air change rates in these wards. Airborne transmission of SARS-CoV-2 must be taken into consideration for preventive measures.

Evaluation of a COVID-19 IgM and IgG rapid test; an efficient tool for assessment of past exposure to SARS-CoV-2.

COVID-19 is the most rapidly growing pandemic in modern time, and the need for serological testing is most urgent. Although the diagnostics of acute patients by RT-PCR is both efficient and specific, we are also crucially in need of serological tools for investigating antibody responses and assessing individual and potential herd immunity. We evaluated a commercially available test developed for rapid (within 15 minutes) detection of SARS-CoV-2-specific IgM and IgG by 29 PCR-confirmed COVID-19 cases and 124 negative controls. The results revealed a sensitivity of 69% and 93.1% for IgM and IgG, respectively, based solely on PCR-positivity due to the absence of a serological gold standard. The assay specificities were shown to be 100% for IgM and 99.2% for IgG. This indicates that the test is suitable for assessing previous virus exposure, although negative results may be unreliable during the first weeks after infection. More detailed studies on antibody responses during and post infection are urgently needed.