Saliva molecular testing bypassing RNA extraction is suitable for monitoring and diagnosing SARS-CoV-2 infection in children

Background

Adults are being vaccinated against SARS-CoV-2 worldwide, but the longitudinal protection of these vaccines is uncertain, given the ongoing appearance of SARS-CoV-2 variants. Children remain largely unvaccinated and are susceptible to infection, with studies reporting that they actively transmit the virus even when asymptomatic, thus affecting the community.

Methods

We investigated if saliva is an effective sample for detecting SARS-CoV-2 RNA and antibodies in children, and associated viral RNA levels to infectivity. For that, we used a saliva-based SARS-CoV-2 RT-qPCR test, preceded or not by RNA extraction, in 85 children aged 10 years and under, admitted to the hospital regardless of COVID-19 symptomatology. Amongst these, 29 (63.0%) presented at least one COVID-19 symptom, 46 (54.1%) were positive for SARS-CoV-2 infection, 28 (32.9%) were under the age of 1, and the mean (SD) age was 3.8 (3.4) years. Saliva samples were collected up to 48 h after a nasopharyngeal swab-RT-qPCR test.

Results

In children aged 10 years and under, the sensitivity, specificity, and accuracy of saliva-RT-qPCR tests compared to NP swab-RT-qPCR were, respectively, 84.8% (71.8%–92.4%), 100% (91.0%–100%), and 91.8% (84.0%–96.6%) with RNA extraction, and 81.8% (68.0%–90.5%), 100% (91.0%–100%), and 90.4% (82.1%–95.0%) without RNA extraction. Rescue of infectious particles from saliva was limited to CT values below 26. In addition, we found significant IgM positive responses to SARS-CoV-2 in children positive for SARS-CoV-2 by NP swab and negative by saliva compared to other groups, indicating late infection onset (>7–10 days).

Conclusions

Saliva is a suitable sample type for diagnosing children aged 10 years and under, including infants aged <1 year, even bypassing RNA extraction methods. Importantly, the detected viral RNA levels were significantly above the infectivity threshold in several samples. Further investigation is required to correlate SARS-CoV-2 RNA levels to viral transmission.

Septic shock 3.0 in severe COVID19 patients: are we missing something clinically important?

Introduction/Purpose

COVID19 can be associated with life-threatening organ dysfunction due to septic shock, frequently requiring ICU admission, respiratory and vasopressor support. Therefore, clear clinical criteria are pivotal to early recognition of patients more likely to have poor outcomes, needing prompt organ support. Although most patients with severe COVID19 meet the Sepsis-3.0 criteria for septic shock, it has been increasingly recognized that, in this population, hyperlactatemia is frequently absent, possibly leading to an underestimation of illness severity and mortality risk.

Purpose

This study aimed to identify the proportion of patients with COVID19 with hypotension despite adequate volume resuscitation, needing vasopressors to have a MAP&gt;65mmHg, with and without hyperlactatemia, in ICU, and describe its clinical outcomes and mortality rate.

Methods

We performed a single-center retrospective cohort study. All adult patients admitted to ICU with COVID19 were eligible and were further divided in 3 groups according to hyperlactatemia (lactate &gt;2mmol/L) and persistent hypotension with vasopressor therapy requirement: (1) sepsis group (without both criteria), (2) vasoplegic shock (with persistent hypotension with vasopressor therapy requirement without hyperlactatemia) and (3) septic shock 3.0 (with both criteria). COVID19 was diagnosed using clinical and radiologic criteria with a SARS-CoV-2 positive RT-PCR test. Qui-square test was used for categorical variables and Kruskal-Wallis and logistic regression were used on continuous variables for statistical assessment of outcomes between groups. Kaplan-Meier survival curve and log-rank test were also obtained.

Results

103 patients (mean age 62 years, 71% males) were included in the analysis (N=45 sepsis, N=25 vasoplegic shock; N=33 septic shock 3.0). SOFA score at ICU admission and ICU length of stay were different between groups (p&lt;0.001). Ventilator-free days and vasopressor-free days were also different between sepsis vs vasoplegic shock and septic shock 3.0 groups (both p&lt;0.001 and p&lt;0.001, respectively), and similar in vasoplegic vs septic shock 3.0 groups (p=0.387 and p=0.193, respectively). Mortality was significantly higher in vasoplegic shock and septic shock 3.0 when compared with sepsis group (p&lt;0.001) without difference between the former two groups (p=0.595). Log rank test of Kaplan-Meier survival curves were also different (p=0.07). Logistic regression identified the maximum dose of vasopressor therapy used (OR 1.065; CI 95%: 1.023–1.108, p=0.02) and serum lactate level (OR 1.543; CI 95%: 1.069–2.23, p=0.02) as the major explanatory variables of mortality rates.

Conclusions

In severe COVID19 patients, the Sepsis 3 criteria of septic shock may exclude patients with a similarly high risk of poor outcomes and mortality rate, that should be equally approached.

Funding Acknowledgement

Type of funding sources: None. Table 1Kaplan-Meier survival curve

Cartilage tissue engineering: current limitations and solutions

Articular cartilage repair remains one of the most intensely studied orthopaedic topics. To date the field of tissue engineering has ushered in new methodologies for the treatment of cartilage defects. The authors' 10-year experience using principles of tissue engineering applied to resurfacing of cartilage defects is reported. Which cell type to use, chondrocytes versus chondroprogenitor cells, and their inherent advantages and disadvantages are discussed. Chondrocytes initially were used as the preferred cell type but were shown to have long term disadvantages in models used by the authors. Mesenchymal stem cells can be used effectively to overcome the limitations experienced with the use of differentiated chondrocytes. The use of mesenchymal stem cells as platforms for retroviral transduction of genes useful in cartilage repair introduces the concept of gene modified tissue engineering. The fundamental conditions for promoting and conducting a viable cartilage repair tissue, regardless of which cell type is used, also were studied. Placement of a synthetic porous biodegradable polymer scaffold was found to be a requirement for achieving an organized repair capable of functionally resurfacing a cartilage defect. A new modular device for intraarticular fixation of various graft composites has been developed. This new cartilage repair device is composed of bioabsorbable polymers and is capable of being delivered by the arthroscope.