July 21 | Daily COVID-19 LST Report


· A retrospective cohort study from New York found that all 16 patients with confirmed SARS-CoV-2 that received a lower extremity computed tomography angiogram (CTA) over a 3-month time period had at least one blood clot on lower extremity CTA compared to just 69% (n=22/36) in propensity-matched patient control data. Limb amputation was also more frequent in COVID-19 patients versus patient controls with peripheral vascular disease, and those presenting with limb ischemia and respiratory symptoms had higher rates of amputation and mortality (p=0.001). Authors use this study to further highlight the morbidity and mortality associated with COVID-19 coagulopathy.

Transmission and Prevention:

· An analysis of contact tracing data from South Korea describes how age and proximity affect SARS-CoV-2 transmission within people living in the same household. They found:

o Household contacts had a higher risk of transmission, with 11.8% of household contacts positive for COVID-19 compared to 1.9% of non-household contacts. - The highest rate of transmission was from the 10-19 year old age group (18.6%) - The lowest rate of transmission was from the 0-9 year old age group (5.3%), which was likely a result of stringent social distancing due to the typically high rate of infection transmission in preschool and daycare settings.

· A retrospective study from the Mayo Clinic explored the efficacy of screening for COVID-19 with reverse transcription polymerase chain reaction (RT-PCR) alone versus RT-PCR plus chest CT in adults undergoing operative procedures. They found that among 625 asymptomatic participants who underwent CT scans, 520 (83.2%) had normal scans, 1 (0.16%) had features typical of COVID-19, and 86 (13.76%) had atypical features (Table 1). Only one participant - who had an atypical CT scan - tested positive by RT-PCR. The authors argue that the addition of CT scan to RT-PCR is not an effective method for screening in a population with low prevalence, though they acknowledge this conclusion may not be generalizable to symptomatic populations or those with high prevalence

· A study evaluating aerosol and surface transmission of SARS-CoV-2 at a designated COVID-19 hospital found that all 135 aerosolized samples, and 88 out of 90 surfaces, were negative for SARS-CoV-2 RNA suggesting that proper disinfection procedures and room ventilation are important and effective means for prevention of nosocomial infection.


· A case report conducted at Changi General Hospital discusses a 45-year-old patient who was diagnosed with Hashimoto's thyroiditis following a COVID-19 infection, indicating a potential link between the hyper-inflammatory state caused by the SARS-CoV-2 virus and the development of autoimmune diseases.

R&D: Diagnosis and Treatments

· An analysis of laboratory tests, imaging results, and vaginal swabs of 13 pregnant persons with suspected COVID-19 found that 12 tested positive for SARS-CoV-2 via RT-PCR from respiratory tract samples, but all vaginal swab samples tested negative. These findings add to the growing evidence that sexual or vertical transmission of SARS-CoV-2 is unlikely and may assist in decision-making regarding obstetrical management.

· A study utilized 109 patient samples to compare the point-of-care variplex test system to RT-PCR systems and found that variplex had a false-negative rate of 83% when compared with PCR. The authors suggest that variplex testing detection of SARS-CoV-2 was low due to lack of RNA extraction, and propose it could be remedied by utilizing loop-mediated isothermal amplification method for RNA extraction prior to variplex testing.

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