Viral cultures, cycle threshold values and viral load estimation for assessing SARS-CoV-2 infectiousness in haematopoietic stem cell and solid organ transplant patients: a systematic review

Early combination therapy of COVID-19 in high-risk patients

PURPOSE

Prolonged shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been observed in immunocompromised hosts. Early monotherapy with direct-acting antivirals or monoclonal antibodies, as recommended by the international guidelines, does not prevent this with certainty. Dual therapies may therefore have a synergistic effect.

METHODS

This retrospective, multicentre study compared treatment strategies for corona virus disease-19 (COVID-19) with combinations of nirmatrelvir/ritonavir, remdesivir, molnupiravir, and/ or mABs during the Omicron surge. Co-primary endpoints were prolonged viral shedding (≥ 106 copies/ml at day 21 after treatment initiation) and days with SARS-CoV-2 viral load ≥ 106 copies/ml. Therapeutic strategies and risk groups were compared using odds ratios and Fisher's tests or Kaplan-Meier analysis and long-rank tests. Multivariable regression analysis was performed.

RESULTS

144 patients were included with a median duration of SARS-CoV-2 viral load ≥ 106 copies/ml of 8.0 days (IQR 6.0-15.3). Underlying haematological malignancies (HM) (p = 0.03) and treatment initiation later than five days after diagnosis (p < 0.01) were significantly associated with longer viral shedding. Prolonged viral shedding was observed in 14.6% (n = 21/144), particularly in patients with underlying HM (OR 3.5; 95% CI 1.2-9.9; p = 0.02). Clinical courses of COVID-19 were mild to moderate with only few adverse effects potentially related to combination treatment.

CONCLUSION

Early combination treatment of COVID-19 effectively prevented prolonged viral shedding in 85.6% of cases. Considering the rapid viral clearance rates and low toxicity, individualized dual therapy approaches may be beneficial in high-risk patients.

Analysis of two sequential SARS-CoV-2 outbreaks on a haematology-oncology ward and the role of infection prevention

Two SARS-CoV-2 nosocomial outbreaks occurred on the haematology ward of our hospital. Patients on the ward were at high risk for severe infection because of their immunocompromised status. Whole Genome Sequencing proved transmission of a particular SARS-CoV-2 variant in each outbreak. The first outbreak (20 patients/31 healthcare workers (HCW)) occurred in November 2020 and was caused by a variant belonging to lineage B.1.221. At that time, there were still uncertainties on mode of transmission of SARS-CoV-2, and vaccines nor therapy were available. Despite HCW wearing II-R masks in all patient contacts and FFP-2 masks during aerosol generating procedures (AGP), the outbreak continued. Therefore, extra measures were introduced. Firstly, regular PCR-screening of asymptomatic patients and HCW; positive patients were isolated and positive HCW were excluded from work as a rule and they were only allowed to resume their work if a follow-up PCR CT-value was ≥30 and were asymptomatic or having only mild symptoms. Secondly, the use of FFP-2 masks was expanded to some long-lasting, close-contact, non-AGPs. After implementing these measures, the incidence of new cases declined gradually. Thirty-seven percent of patients died due to COVID-19. The second outbreak (10 patients/2 HCW) was caused by the highly transmissible omicron BA.1 variant and occurred in February 2022, where transmission occurred on shared rooms despite the extra infection control measures. It was controlled much faster, and the clinical impact was low as the majority of patients was vaccinated; no patients died and symptoms were relatively mild in both patients and HCW.

Clinical outcomes and immunological features of COVID-19 patients receiving B-cell depletion therapy during the Omicron era

Background: The clinical outcomes and immunological features of coronavirus disease 2019 (COVID-19) patients receiving B-cell depletion therapy (BCDT), especially in Omicron variant era, have not been fully elucidated. We aimed to investigate the outcomes and immune responses of COVID-19 patients receiving BCDT during the Omicron period.Methods: We retrospectively compared clinical outcomes between COVID-19 patients treated with BCDT (the BCDT group) and those with the same underlying diseases not treated with BCDT (the non-BCDT group). For immunological analyses, we prospectively enrolled COVID-19 patients receiving BCDT and immunocompetent COVID-19 patients as controls. We measured humoral and cellular immune responses using the enzyme-linked immunosorbent assay and flow cytometry.Results: Severe to critical COVID-19 was more frequent in the BCDT group than in the non-BCDT group (41.9% vs. 28.3%, p = .030). BCDT was an independent risk factor for severe to critical COVID-19 (adjusted odds ratio [aOR] 2.21, 95% confidence interval [CI] 1.21-4.04, p = .010) as well as for COVID-19-related mortality (aOR 4.03, 95% CI 1.17-13.86, p = .027). Immunological analyses revealed that patients receiving BCDT had lower anti-S1 IgG titres and a tendency to higher proportions of activated CD4+ T-cells than the controls.Conclusions: BCDT was associated with worse COVID-19 outcomes in the Omicron period. Humoral immune response impairment and T-cell hyperactivation were the main immunological features of COVID-19 patients treated with BCDT, which may have contributed to the worse outcomes of COVID-19 in this population.

Reduction of mycophenolate mofetil dosage to limit prolonged viral shedding in solid organ transplant recipients with COVID-19: Two case reports

Solid organ transplant (SOT) recipients with coronavirus disease-2019 (COVID-19) experience prolonged viral shedding, and they are forced to stay in the hospital because of the requirement for COVID-19 isolation. Here, we present two cases (lung and renal transplant recipients), wherein the isolation period was shortened by reducing the dosage of mycophenolate mofetil (MMF). Both patients recovered well from COVID-19 pneumonia. This case study suggests that a reduction in MMF dosage may lead to a shorter hospitalization period in SOT recipients with COVID-19.

Nasopharyngeal SARS-CoV-2 viral load kinetics using digital PCR

Background

The relationship between the viral kinetics of SARS-CoV-2 and clinical outcomes remains unclear.

Methods

A convenience sample of 955 remnant nasopharyngeal swabs collected during routine care between 11/18/20 and 9/26/21 were analyzed using digital PCR and associated clinical data extracted from the medical record. 18 individuals had >1 sample within 30 days of onset of symptoms.

Results

Paired samples were an average of 6 [range: 0-13] days apart. Four individuals sampled twice on the same day had a median 0.52 log10 viral load difference between samples. Of the remaining, 12 individuals had a decrease in viral load over time, with an average decay of -0.23 log10/day.

Conclusions

Our study found a similar rate of viral decay to others, but did not find associations between viral kinetics and clinical outcomes. Larger studies would be useful to support the use of this measurement as a surrogate endpoint for therapeutic studies.

Revisiting the personal protective equipment components of transmission-based precautions for the prevention of COVID-19 and other respiratory virus infections in healthcare

The COVID-19 pandemic highlighted some potential limitations of transmission-based precautions. The distinction between transmission through large droplets vs aerosols, which have been fundamental concepts guiding infection control measures, has been questioned, leading to considerable variation in expert recommendations on transmission-based precautions for COVID-19. Furthermore, the application of elements of contact precautions, such as the use of gloves and gowns, is based on low-quality and inconclusive evidence and may have unintended consequences, such as increased incidence of healthcare-associated infections and spread of multidrug-resistant organisms. These observations indicate a need for high-quality studies to address the knowledge gaps and a need to revisit the theoretical background regarding various modes of transmission and the definitions of terms related to transmission. Further, we should examine the implications these definitions have on the following components of transmission-based precautions: (i) respiratory protection, (ii) use of gloves and gowns for the prevention of respiratory virus infections, (iii) aerosol-generating procedures and (iv) universal masking in healthcare settings as a control measure especially during seasonal epidemics. Such a review would ensure that transmission-based precautions are consistent and rationally based on available evidence, which would facilitate decision-making, guidance development and training, as well as their application in practice.

Judicious ending of isolation based on reverse transcription-polymerase chain reaction (RT-PCR) cycle threshold only for patients with coronavirus disease 2019 (COVID-19) requiring in-hospital therapy for longer than 20 days after symptom onset

BACKGROUND

For patients with coronavirus disease 2019 (COVID-19) requiring hospitalization, extending isolation is warranted. As a cautious protocol, ending isolation based on polymerase chain reaction cycle threshold (Ct) value was introduced for patients requiring therapy for >20 days after symptom onset.

METHOD

We compared a Ct-based strategy using Smart Gene® between March 2022 and January 2023 with a preceding control period (March 2021 to February 2022) when two consecutive negative reverse transcription-polymerase chain reaction tests using FilmArray® were required for ending isolation. Ct was evaluated on day 21, and ending isolation was permitted in patients with Ct ≥ 38. Although patients with Ct 35-37 were transferred to a non-COVID-19 ward, isolation was continued.

RESULTS

The duration of stay on a COVID-19 ward in the Ct group was 9.7 days shorter than that in controls. The cumulative number of tests was 3.7 in controls and 1.2 in the Ct group. There was no nosocomial transmission after ending isolation in either group. The number of days from symptom onset to testing was 20.7 ± 2.1 in Ct group, and five patients had Ct < 35, nine Ct 35-37, and 71 Ct ≥ 38. No patients were moderately or severely immunocompromised. Steroid use was an independent risk factor for prolonged low Ct (odds ratio 9.40, 95% confidence interval 2.31-38.15, p = 0.002) CONCLUSIONS: The efficacy of ending isolation based on Ct values could improve bed utilization without the risk of transmission among patients with COVID-19 requiring therapy for >20 days after symptom onset.