Duration of SARS-CoV-2 RNA Shedding Is Significantly Influenced by Disease Severity, Bilateral Pulmonary Infiltrates, Antibiotic Treatment, and Diabetic Status: Consideration for Isolation Period

Advancing COVID-19 diagnostics: rapid detection of intact SARS-CoV-2 using viability RT-PCR assay

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). Commonly used methods for both clinical diagnosis of SARS-CoV-2 infection and management of infected patients involve the detection of viral RNA, but the presence of infectious virus particles is unknown. Viability PCR (v-PCR) uses a photoreactive dye to bind non-infectious RNA, ideally resulting in the detection of RNA only from intact virions. This study aimed to develop and validate a rapid v-PCR assay for distinguishing intact and compromised SARS-CoV-2. Propidium monoazide (PMAxx) was used as a photoreactive dye. Mixtures with decreasing percentages of intact SARS-CoV-2 (from 100% to 0%) were prepared from SARS-CoV-2 virus stock and a clinical sample. Each sample was divided into a PMAxx-treated part and a non-PMAxx-treated part. Reverse transcription-PCR (RT-PCR) using an in-house developed SARS-CoV-2 viability assay was then applied to both sample sets. The difference in intact SARS-CoV-2 was determined by subtracting the cycle threshold (Ct) value of the PMAxx-treated sample from the non-PMAxx-treated sample. Mixtures with decreasing concentrations of intact SARS-CoV-2 showed increasingly lower delta Ct values as the percentage of intact SARS-CoV-2 decreased, as expected. This relationship was observed in both high and low viral load samples prepared from cultured SARS-CoV-2 virus stock, as well as for a clinical sample prepared directly from a SARS-CoV-2 positive nasopharyngeal swab. In this study, a rapid v-PCR assay has been validated that can distinguish intact from compromised SARS-CoV-2. The presence of intact virus particles, as determined by v-PCR, may indicate SARS-CoV-2 infectiousness.

IMPORTANCE

This study developed a novel method that can help determine whether someone who has been diagnosed with coronavirus disease 2019 (COVID-19) is still capable of spreading the virus to others. Current tests only detect the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA, but cannot tell whether the particles are still intact and can thus infect cells. The researchers used a dye that selectively blocks the detection of damaged virions and free RNA. They showed that this viability PCR reliably distinguishes intact SARS-CoV-2 capable of infecting from damaged SARS-CoV-2 or free RNA in both cultured virus samples and a clinical sample. Being able to quickly assess contagiousness has important implications for contact tracing and safely ending isolation precautions. This viability PCR technique provides a simple way to obtain valuable information, beyond just positive or negative test results, about the actual risk someone poses of transmitting SARS-CoV-2 through the air or surfaces they come into contact with.

Influence of vaccination on critical COVID-19 patients with acute respiratory failure: a retrospective cohort study

BACKGROUND

Despite vaccines' effectiveness in reducing COVID-19 infection rates and disease severity, their impact on critical patients presenting with acute respiratory failure is elusive. The aim of this study was to further investigate the influence of vaccination on mortality rates among severely ill COVID-19 patients experiencing acute respiratory failure.

METHODS

This retrospective cohort study was carried out at a tertiary medical center in Taiwan. From April to September 2022, patients who tested positive for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through reverse transcription polymerase chain reaction (RT-PCR) and subsequently experienced acute respiratory failure were included in the study. Baseline characteristics, including vaccination history, along with information regarding critical illness and clinical outcomes, were gathered and compared between patients who received the vaccine and those who did not.

RESULTS

A total of 215 patients with COVID-19 exhibiting acute respiratory failure, as confirmed via RT‒PCR, were included in the analysis. Of this cohort, sixty-six (30.7%) patients died within 28 days. Neither administration of the vaccine nor achievement of primary series vaccination status had a significantly different effect on 28 day mortality, number of viral shedding events, acute respiratory distress syndrome (ARDS) incidence or other clinical outcomes. Patients who received the booster vaccine and completed the primary series showed a tendency of increased 28 days of ventilator-free status, though this difference was not statistically significant (p = 0.815).

CONCLUSIONS

Vaccination status did not significantly influence mortality rates, the occurrence of ARDS, or the viral shedding duration in COVID-19 patients with acute respiratory failure.

[Clinical efficiency and safety of riamilovir under various dosage regimens for treatment of acute respiratory viral infections in adults]

AIM

To evaluate the clinical efficacy and safety of antiviral drug riamilovir in patients with acute respiratory viral infections (ARVI) of non-coronavirus (SARS-CoV-2) etiology with different dosing regimens.

MATERIALS AND METHODS

The study included 150 patients with ARVI aged 18-27 years (50 patients received riamilovir in the regimen of 250 mg 3 times a day for 5 days, 50 patients received riamilovir in the off label regimen of 250 mg 5 times a day for 5 days, 50 patients received only pathogenetic treatment).

RESULTS

The use of riamilovir in both treatment regimens led to a reduction in the duration of inpatient treatment. The shortest periods of hospitalization were noted in patients who received the study drug at higher daily dosages. The use of riamilovir reduced the duration and severity of general infectious manifestations of the disease, while the shortest total duration of fever and a number of respiratory tract syndromes was registered among people who received riamilovir in the regimen of 1250 mg per day for 5 days, no adverse events were registered, additionally, 100% elimination of ARVI pathogens was noted in 1250 mg per day group.

CONCLUSION

Riamilovir has shown clinical efficacy and a good safety profile in in both treatment regimens. The dosage regimen of 1250 mg per day led to more significant clinical effects and to 100% elimination of ARVI pathogens in the study group by the 6th day of hospitalization.