COVID-19 Delta is a Big Step Backward

James Katz MD, MPH
2 min readJul 23, 2021

Time to Use Masks Again in Indoors Public Spaces

COVID-19 from CDC/Unsplash

The Dangerous Delta COVID-21 Virus

The Delta variant of COVID-19 is the fourth major mutation of the pandemic. It has modified spike proteins which attach more efficiently to human cells than COVID-19. Its genetic programming is more potent — infected cells produce a thousand times more virus particles than its predecessor . A person with Delta can infect others within four days while COVID-19 took six days. Unvaccinated people of all ages, when hospitalized, are twice as likely to need mechanical ventilation. Vaccinated people can get a flu type illness (with no loss of smell). It acts like a different virus; some are calling it a new name — COVID-21 appears to be the consensus.

Rnaught is a measure of infectivity. The original COVID-19 was rated 2.5 in China. In the US, it was 3.3 in Queens, New York at the peak. Delta has an Rnaught of closer to 6.0. Rnaught is an exponential scale, so Delta is potentially 10,000 times more infectious than the original COVID-19 epidemic.

In simple terms, the person in front of you in line at the grocery store may be exhaling highly concentrated clouds of more dangerous virus particles.. In settings where 40 minutes exposure could transmit COVID-19, you can get Delta in five minutes. In a computer model, where COVID-19 infected 42,000 people in a month, Delta would infect 520,000 people.

I’m a doctor and I am vaccinated. I am wearing a mask in enclosed or crowded spaces and washing my hands. I am still going to well ventilated restaurants, but not bars. Meeting people outdoors is fine. Those masks sitting in your kitchen closet need to be worn again in closed spaces shared with people you don’t know.

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James Katz MD, MPH

Medical practitioner/investigator who goes where the evidence leads.