A Science and Technology Blog
In a conversation, Dr. Gautam Menon, Professor of Physics and Biology at Ashoka University and co-author of COVID-19 modelling studies, and Dr. Giridhara R. Babu, Professor of Epidemiology at the…
While the low sensitivity of rapid antigen tests arises from not isolating the viral RNA from the swab samples and amplification of the DNA before detection, the two indigenously developed tests follow these two vital steps, the reason why the sensitivity and specificity are far superior than that of the rapid antigen tests.
University of Illinois at Urbana-Champaign began an ambitious initiative in mid-August to repeatedly test for free all students, faculty and staff for novel coronavirus using a rapid saliva-based test that…
While rapid antigen tests used repeatedly in the same population can be used for screening, RT-PCR tests are designed for use with symptomatic people and so need not be low-cost…
Analysis of sewage sludge for a period of 10 weeks in the New Haven, Connecticut metropolitan area in the U.S. during the COVID-19 outbreak period March 19-June 1 helped know the swing in coronavirus cases up to two days before samples could be collected, one-four days before hospital admissions and six-eight days before positive results were reported.
By stating that “all individuals who wish to get themselves tested” are eligible for tests on demand, the ICMR is theoretically making all of India’s 1.3 billion people eligible for a test and also demand a test repeatedly without an upper limit, even when the country does not have the capacity to undertake such a massive exercise. Clearly, the latest advisory is over ambitious and has been framed without much application of mind.
Using the cycle threshold (Ct) values to infer COVID-19 disease severity or infectiousness may be problematic. Cycle threshold values can be suggestive of the amount of virus in an infected person but there is no reliable way of correlating the Ct value with COVID-19 disease severity or infectiousness. But largely, when the Ct value is over 35, a person is unlikely to be infectious. There are many variables that can alter the Ct value of a sample.
In a mass-screening study of 1,924 asymptomatic persons, self-collected saliva samples had sensitivity (92%) and specificity (over 99.9%) comparable to nasopharyngeal specimens — sensitivity 86% and specificity over 99.9%. The…
