(With inputs from Dr Monica Vasudev)

830: Three drugs better

Patients hospitalized with COVID-19 receiving a combination therapy with three antivirals, including-protease inhibitor lopinavir-ritonavir (Kaletra), nucleoside analogue ribavirin, and injectable interferon beta-1b (Betaseron, Extavia), exhibited significantly shorter median time to a negative SARS-CoV-2 test compared to controls, revealed a small phase II trial. Median number of days from initiation of study treatment to a negative test result, the trials primary endpoint, was 7 days compared with 12 days in the 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 in a paper from Iceland. This implies that a ton of people are still susceptible to the disease. No herd immunity is developing, and the mortality rate is high, and that were going to be stuck inside for a long time.

However, of late, using antibody tests, researchers are sampling asymptomatic people to figure out who had the disease. In early April, researchers from Germany published a study, which found that 70 out of 500 people tested in a hard-hit area had coronavirus antibodies. That amounts to 14%. Translating that to the entire population puts the ratio of undocumented to documented COVID-19 at about 5 to 1.

A much criticized California seroprevalence study involving 3300 individuals noted that 50 were positive, amounting to merely 1.5%, but in an area that hadnt 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) exhibited a seroprevalence rate of about 20%. This translates to an undocumented-to-documented ratio of 10 to 1. This scenario 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. Consider that you have an antibody test that is 98% specific. This means that only 2 out of 100 people will go on to have a false positive. It will be estimated that 2% of the population has had the disease. If that is done in a random sample of America, youd estimate that there have been 6 million coronavirus infections, compared with the roughly 1 million weve detected, thus allowing you to cut the death rate down by a factor of 6.

However, that result was just due to random chance. A 95% specific test would conclude that at least 15 million Americans have already had exposure, allowing you to take the observed death rate of 5.7% and reduce it to a much more comfortable 0.3%.

832:  Mutation: Scientists have cautioned that a mutation called D614G in the Spike protein region of the SARS-CoV-2 virus “is of urgent concern,” as it makes the virus more contagious.

Dr KK Aggarwal

Dr K K Aggarwal, President CMAAO, HCFI, Past National President IMA, Chief Editor Medtalks