CMAAO Coronavirus Facts and Myth Buster: Immunological memory; Fluvoxamine in COVID; T-cell test |
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CMAAO Coronavirus Facts and Myth Buster: Immunological memory; Fluvoxamine in COVID; T-cell test
Dr KK Aggarwal,  24 November 2020
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With input from Dr Monica Vasudev

1158:  Most COVID-19 survivors may develop lasting protection if they become reinfected. A study of 185 patients, including 41 who had been infected over six months prior, by investigators at La Jolla Institute for Immunology in California, revealed that immune system recognized the novel coronavirus for at least 8 months.  Memory B cells were found to be more abundant six months after infection as compared to at one month, reported the researchers in a paper posted on bioRxiv. The immune system can remember the virus for years.

[SOURCE: Reuters; https://bit.ly/3lJkz2q bioRxiv, online November 16, 2020.]

1159: Early treatment with fluvoxamine may help prevent respiratory decline in patients with mild symptomatic COVID-19. In a recent trial, none of the patients who took fluvoxamine within 7 days of first symptoms developed serious breathing difficulties or needed hospitalization for respiratory deterioration. The study was published online in the Journal of the American Medical Association.

The mechanism involves activation of the sigma-1 receptor. The activation depresses cytokine release and the inflammatory response. Other possible mechanisms could possibly include the inhibition of platelet activation and modulation of autophagy. Coronaviruses tend to take over some autophagy machinery to remodel membranes for replicating their genomes. Hence, this last mechanism might actually be antiviral.

Overall, 152 nonhospitalized adults (mean age, 46; 72% women) with confirmed SARS-CoV-2 infection and mild COVID-19 symptoms starting within 7 days and oxygen saturation of 92% or more were included in the study.  Eighty were randomized to receive 100 mg fluvoxamine three times daily for 15 days while 72 were randomized to matching placebo.

None of the 80 patients taking fluvoxamine had clinical deterioration compared to 6 of 72 (8.3%) patients given placebo, for an absolute difference of 8.7%.

[Source: Medscape]

1160: Pfizer and Moderna work validates that of several small biotechnology firms, which have been striving to prove an idea that was once considered unorthodox: The human body can act as its own vaccine factory. Both the Pfizer and Moderna vaccines work by injecting people with customized genetic code which instructs the human cells to make key virus proteins to induce an immune response.

mRNA instructions are introduced for the cells to make a portion of a virus, which is recognized by the immune system as a threat and is countered with a protective response. There is no involvement of any actual virus. The appeal of mRNA vaccines is that they are plug-and-play. The mRNA vehicle does not need to change, only the specific genetic instructions it carries. If the virus mutates, the details of the instructions can be changed accordingly.

[Source: Mint]

1161: A novel T-cell test seems to be more effective than a commercially available antibody test to detect past infections. Preliminary findings from a study reveal that the T-cell test could identify 97% (68/70) of past COVID-19 infections among residents of Vo, Italy, in comparison with 77% (54/70) among those tested with an antibody test. T-cell response was greater in symptomatic individuals, compared to those without symptoms. However, there appeared to be no correlation between antibody levels and disease severity.

The test, called T-Detect Assay, has been developed by Seattle-based Adaptive Biotechnologies. It will first be provided through a Clinical Laboratory Improvement Amendment (CLIA). As per Lance Baldo, MD, chief medical officer of Adaptive Biotechnologies, “T cells are emerging as another key indicator for past infection and immunity to the novel coronavirus.” There is a precedent for using T-cell testing to diagnose past infection, the most common being the FDA-approved test for TB or the QuantiFERON test. Additionally, skin testing for TB and a skin test for coccidioides are T-cell tests.

[Source: Medscape]

 

Dr KK Aggarwal

President CMAAO, HCFI and Past National President IMA

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