Sunday, May 10, 2020



Dr K K Aggarwal
President Confederation of Medical Associations of Asia and Oceania, HCFI, Past National President IMA, Chief Editor Medtalks
With inputs from Dr Monica Vasudev

830: Three drugs better

Patients hospitalized with COVID-19 who received a combination therapy with three antivirals -- protease inhibitor lopinavir-ritonavir (Kaletra), nucleoside analogue ribavirin, and injectable interferon beta-1b (Betaseron, Extavia) -- showed significantly shorter median time to a negative SARS-CoV-2 test versus controls, a small phase II trial found. Median number of days from start of study treatment to a negative test result, the trial's primary endpoint, was 7 days compared with 12 days in a control group that only received lopinavir-ritonavir, reported Kwok-Yung Yuen, MD, of the University of Hong Kong, and colleagues writing in The Lancet.

831: COVID formulas revisited
Documented PCR-positive COVID-19 cases are just the tip of the iceberg.
1.      In US 5.7% of people in that tip have died.
2.       How much iceberg is under the water:
Steamroller COVID: There were roughly two undocumented cases of COVID-19 for each documented case. It means that a ton of people are still susceptible to the disease. No herd immunity is developing, the mortality rate is high, and we're going to be stuck inside for a long time.
But recently, using antibody tests, researchers are starting to sample asymptomatic people to figure out who had the disease. In early April, German researchers published this study, which found that 70 out of 500 people tested in a hard-hit area had coronavirus antibodies. That's 14%. Translating that to the entire population put the ratio of undocumented to documented COVID-19 at about 5 to 1.
A much criticized California seroprevalence study of 3300 individuals found that 50 were positive — just 1.5% — but in an area that hadn't seen many symptomatic cases, putting the undocumented-to-documented ratio at 85 to 1.
Windstorm COVID : Governor Andrew Cuomo reported that sampling of New York City grocery store shoppers (perhaps not the most random sample) has a seroprevalence rate of around 20%. That implies an undocumented-to-documented ratio of 10 to 1. This is the COVID that allows us to open up more quickly, assuming that antibodies are protective.

So which COVID is it?

Antibody tests: No test is perfect. The false positives are particularly high. Imagine you have an antibody test that is 98% specific. Only 2 out of 100 people will have a false positive. You'll estimate that 2% of the population has had the disease. If you did that in a random sample of America, you'd estimate that there have been 6 million coronavirus infections, compared with the roughly 1 million we've detected, allowing you to comfortably cut the death rate down by a factor of 6 — making us all feel a bit better.
But, of course, that result was just due to random chance. A 95% specific test would lead to a conclusion that at least 15      million Americans have already been exposed, allowing you to take the observed death rate of 5.7% and cut it right down to a much more comfortable 0.3%.
832:  Mutation: Scientists have warned that a mutation called D614G in the Spike protein region of the SARS-CoV-2 virus — which causes Covid-19 — “is of urgent concern,” as it makes the virus more contagious.

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