155 CMAAO CORONA FACTS and MYTH Round the globe
Dr K Aggarwal
With inputs from Dr Monica Vasudev
986: COVID-19 patients were 27 times more likely than others to have lost their sense of smell. But they were only 2.6 times more likely to have fever or chills. So then why are we measuring the temperature as a detection method for asymptomatic COVID-19? Why not measure the smell and taste as the screening method.
987: How Does Antigen Test Work: First category includes RT-PCR, TrueNat, CBNAAT and Antigen test—these tests can detect the virus in the body. The second category - called serologic test - can detect antibodies produced in the human body to protect it against the virus.
The antigen is a substance (part of the virus) which incites an immune response. So, if the nasal or throat swab shows the presence of antigen, it means the person is infected.
While the RT-PCR test involves several steps and produces results within five to six hours, an antigen test can give results within 30 minutes. Antigen test costs Rs 450 while an RT-PCR costs Rs 2,400.
Several companies approached ICMR to get approval for their antigen kit but the medical body has approved only one company, SD Biosensor, which manufactures Standard Q COVID-19 Ag kit.
ICMR’s study shows that Standard Q COVID-19 Ag kit can detect an uninfected person as negative in almost 100 per cent cases. However, it can diagnose only 50 per cent infected person as positive.
This means that if out of 100 people, 90 are uninfected, and 10 infected, it can show five as positive and rest all negative. So, 90 are truly negative and five are false negative.
Due to this anomaly, experts believe, all 95 ideally should go for RT-PCR test. But ICMR says that only those who have Covid-19 symptoms but are diagnosed negative in antigen test should go for RT-PCR test.
It would be desirable to also pick up asymptomatic false negatives as they can spread disease being unaware that they are positive. (outlook India)
988: ICMR got the Tamil Nadu government's permission to study the efficacy of the Bacillus Calmette- Gurin (BCG) vaccine in senior citizens in the fight against COVID-19, at its National Institute for Research in Tuberculosis (NIRT)
989: A low lymphocyte count in people presenting to the hospital with COVID-19 could help physicians identify those at higher risk for intensive care unit (ICU) admission. Patients with lymphocytopenia had a more than threefold increased risk for requiring ICU care compared with people with normal lymphocyte counts at time of admission. Acute kidney injury (AKI) also was more common among people with low absolute lymphocyte counts. [July 10 in the International Journal of Laboratory Hematology].
This study shows that absolute lymphocyte count below 1000 on admission is associated with ICU admission and organ damage,
990: Moderna Vaccine Produces Immune Response in Patients
Every person who received Moderna's COVID-19 vaccine, mRNA-1273, developed an immune response to the virus that causes it. Researchers also reported some side effects in the 45 people in the phase I study, but no significant safety issues. The vaccine resulted in a robust immune response.
The company is already testing the vaccine in a larger group of people, known as a phase II trial. It plans to begin phase III trials in late July. Phase III trials involve testing the vaccine on an even larger group and are the final step before FDA approval.
The study results are published in The New England Journal of Medicine. The study was led by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health.
Moderna's vaccine uses messenger RNA, also called mRNA. It carries the instruction for making the spike protein, a key protein on the surface of the virus that allows it to enter cells when a person is infected. After it's injected, it goes to the immune cells and instructs them to make copies of the spike protein, acting as if the cells have been infected with the actual coronavirus. This allows other immune cells to develop immunity.
In the study, participants were divided into three groups of 15 people each. All groups received two vaccinations 28 days apart. Each group received a different strength of the vaccine — either 25, 100, or 250 micrograms.
Every person in the study developed antibodies that can block the infection. Most commonly reported side effects after the second vaccination in the 100-microgram group were fatigue, chills, headache, and muscle pains, ranging from mild to moderately severe.
The phase II study has 300 heathy adults ages 18-55, along with another 300 ages 55 and older. Moderna says it hopes to include about 30,000 participants at the 100-microgram dose level in the U.S. for the phase III trial. The estimated start date is July 27. [N Engl J Med. Published online July 14, 2020.]