CMAAO CORONA FACTS and MYTH  Lab errors with new strain

Author: Dr K Aggarwal, President CMAAO, HCFI, with input from Dr Monica Vasudev

New Delhi, January 09, 2021:

In a group of hospitalized COVID-19 patients with no prior neurologic disease, 37.4% showed abnormalities on neurologic exam 6 months later — most commonly cognitive deficits, hyposmia, and postural tremor — according to Alessandro Padovani, MD, PhD, of the University of Brescia, and co-authors. The findings were reported in a medRxiv preprint and have not undergone peer review.

Patients also noted fatigue, memory impairment, and sleep disorders. The severity of SARS-CoV-2 infection was an important predictor, together with age and premorbid condition, of long-term neurological symptoms and features in the cohort.

Earlier research showed that 87% of patients hospitalized with COVID-19 reported persistence of at least one lingering symptom, notably fatigue and dyspnea, 60 days after discharge. Fatigue and dyspnea also were the most prevalent symptoms reported during infection and at 3-month follow-up in an analysis of both hospitalized and non-hospitalized COVID-19 patients.

The checklist including symptoms related to central, peripheral, myopathic, and cognitive manifestations. The exam assessed cranial nerves; motor, sensory, cerebellar, and basal ganglia-related function; deep tendon reflexes; pyramidal signs; and global cognitive function using the Montreal Cognitive Assessment (MoCA).

Of 165 patients, the most common symptoms reported at follow-up were fatigue (34.1%), memory complaints (30.8%), sleep disorders (30.8%), and myalgias (29.6%), followed by depression or anxiety symptoms (26.0%), blurring or other visual disturbances (19.5%), paresthesia (18.3%), and hyposmia/dysgeusia (16.5%).

In addition, 14.0% of patients reported urinary dysfunction, 13.0% confusion/dizziness, 12.2% dizziness/hypotension, 10.7% gait disturbances, and 8.5% postural instability or falls.

A total of 105 patients were evaluated further by neurologic exam and cognitive screening. Of these, 42 people showed neurologic abnormalities: 19 had hyposmia/dysgeusia, 15 had enhanced physiological tremor, six had low-limb hypoesthesia, three had low-limb motor deficits, and 17 had cognitive deficits according to MoCA Italian validated norms. None of these patients had a history of cognitive impairment, Padovani noted.

Neurologic abnormalities seen on exam were associated with older age (P=0.005), higher premorbid comorbidity index (P=0.001), worse BCRSS scores (P=0.05), longer hospitalization duration (P=0.002), and higher number of neurologic symptoms reported (P=0.007). Length of hospitalization (P=0.02) and premorbid comorbidity index (P=0.03) predicted neurologic abnormalities.

Cognitive impairment was specifically associated with severity of COVID-19, independently of age and pre-morbid conditions.

Results from Pfizer/BioNTech’s late-stage clinical trial suggest one dose of the vaccine might confer some level of immunity, with an efficacy rate around 52%. But the one-dose regimen has not received any sort of government approval, as vaccine efficacy jumps to 95% after the second dose.

Only a small fraction of asymptomatic close contacts of COVID-19 cases ultimately tested positive after an initial negative test followed by quarantining for 7 days, Vermont health officials found.

Of 977 asymptomatic contacts of COVID-19 cases from May to November, 34 (3%) tested positive for COVID-19 after the week-long quarantine, reported Veronica Fialkowski, MPH, of the Vermont Department of Health in Burlington, and colleagues, writing in the CDC’s Morbidity and Mortality Weekly Report.

US regulators warned about the potential risk for false negative results with molecular tests for SARS-CoV-2 due to mutations such as a recently detected B.1.1.7 variant of the virus.

The US FDA warned that false negative results can occur with any molecular test for the detection of SARS-CoV-2 if a mutation occurs in the part of the virus’s genome assessed by that test. The risk that these mutations will affect overall testing accuracy is low.

Like all viruses, SARS-CoV-2 was expected to mutate over time, as seen with the emergence of the B.1.1.7 variant, the FDA said.

In its Friday letter to healthcare workers, the FDA said that its analysis to date has identified three molecular tests that have received emergency use authorization (EUA) whose performance could be affected by SARS-CoV-2 genetic variants.

1. Accula SARS-CoV-2 Test: The FDA’s analysis, indicates that this test’s performance may be affected when a SARS-CoV-2 virus patient sample having a genetic variant at position 28881 (GGG to AAC) is tested. While the impact does not appear to be significant, the FDA is providing this alert.
2.  TaqPath COVID-19 Combo Kit and Linea COVID-19 Assay Kit: The FDA said that the detection pattern that appears with the TaqPath and Linea diagnostic tests when certain genetic variants are present may help with early identification of new variants to reduce further spread of infection.
3.  The agency also advised healthcare professionals to be aware of the pattern of detection associated with certain mutations, including the B.1.1.7 variant, specifically a pattern of 2/3 positive targets showing the S-gene dropout (reduced sensitivity with the S-gene target), when using the TaqPath COVID-19 Combo Kit, and a pattern of 1/2 positive targets showing the S-gene dropout when using the Linea COVID-19 Assay Kit.

1. Be aware that genetic variants of SARS-CoV-2 arise regularly, and false negative test results can occur
2. Be aware that tests that use multiple genetic targets to determine a final result are less likely to be affected by increased prevalence of genetic variants

iii.             Consider negative results in combination with clinical observations, patient history, and epidemiological information

1. Consider repeat testing with a different test (with different genetic targets) if COVID-19 is still suspected after receiving a negative test result
2. In South Africa, another variant of SARS-CoV-2 (known as 20C/501Y.V2 or B.1.351 lineage) has emerged independently of the B.1.1.7 lineage. This variant shares some mutations with the B.1.1.7 lineage. The CDC said that cases attributed to this variant have been detected outside of South Africa.