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Saturday, July 30, 2021

This week brought us the news that the Delta Variant of COVID-19 is as contagious as chickenpox. The information came to light through an internal CDC document leaked to the Washington Post and was confirmed by CDC Director Dr. Rochelle Wallensky. The report, which consists of a series of slides, goes on to state that Delta is more transmissible than smallpox, the common cold, or the flu. When someone sneezes near you at work or at school do you ever cringe a little and hope you don’t catch it? Maybe you even wished they’d stay home? That’s the situation we’re in with Delta, except that you may not know they’re contagious. They may not even know it themselves. They may even be vaccinated.

Here’s the now-famous chickenpox slide:

From: “Internal CDC document on breakthrough infections,” link below

Several reasons why the Delta variant is a game changer have been suggested by recent studies. For example:

  1. A recent study in China compared viral load in people infected with the original strain to people infected with Delta. They found the Delta variant was detectable sooner and produced a viral load up to 1,260 times higher than the original strain.
  2. A new report in Morbidity and Mortality Weekly Report (the Barnstable report, link below) indicates that vaccinated people can transmit the virus as much as unvaccinated people.
  3. The internal CDC document cites three studies (from Canada, Singapore, and Scotland) that indicate that the Delta variant may cause more severe disease than previous strains.
CDC Variant Proportions:
Delta (dark orange) increases April-July

This has brought about the CDC’s new guidelines on masks for vaccinated individuals indoors if they are in areas of high transmission. Before Delta, there was evidence that people who were fully vaccinated were less likely to test positive and less likely to transmit the virus than unvaccinated people. The new data brings this into question. The vaccinations are still very effective at reducing sickness, hospitalizations and death, which were the criteria for efficacy when they were originally tested.

In the Barnstable study, for example, a cluster of cases was found that originated over the Fourth of July holiday when thousands of visitors were in the area. 469 cases were identified through contact tracing from the first cluster and of these about 74% were in fully vaccinated people, of whom only 4 were hospitalized. There were no deaths. The report itself emphasizes that this was a small study and more data is needed.

There is a lot to unpack in the CDC report and the studies it cites, and I’m not going to even try. What does seem clear is that we have a moving target. As the CDC chart on the left shows, Delta has only been dominant in the U.S. since mid-June. Most of the studies that we have were done before the Delta variant was prevalent. And it won’t stop with Delta. There will be more variants of concern before this is over.

As the CDC presentation says on its last slide: “Acknowledge the war has changed.”

Today’s Notable Headlines

“Read: Internal CDC document on breakthrough infections”, updated July 30, 2021. The Washington Post. https://www.washingtonpost.com/context/cdc-breakthrough-infections/94390e3a-5e45-44a5-ac40-2744e4e25f2e/?_=1

“CDC: Delta as contagious as chickenpox,” CIDRAP, Center for Infectious Disease Research and Policy, July 30, 2021.

“CDC document warns Delta variant appears to spread as easily as chickenpox and cause more severe infection,” CNN, July 30, 2021. https://www.cnn.com/2021/07/29/politics/cdc-masks-covid-19-infections/index.html

“COVID Delta variant as transmissible as chickenpox: US report,” Al Jazeera, July 30, 2021. https://www.aljazeera.com/news/2021/7/30/us-agency-coronavirus-delta-variant-as-contagious-as-chicken-pox

Source articles:

“How the Delta variant achieves its ultrafast spread,” Nature, July 21, 2021. https://www.nature.com/articles/d41586-021-01986-w

“Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021,” Morbidity and Mortality Weekly Report, July 30, 2021. https://www.cdc.gov/mmwr/volumes/70/wr/mm7031e2.htm?s_cid=mm7031e2_e&ACSTrackingID=USCDC_921-DM62612&ACSTrackingLabel=MMWR%20Early%20Release%20-%20Vol.%2070%2C%20July%2030%2C%202021&deliveryName=USCDC_921-DM62612

COVID Data Tracker, CDC, https://covid.cdc.gov/covid-data-tracker/#variant-proportions

Why am I doing this?

The coronavirus pandemic will be indelibly written on our memories just as the Great Depression or the Battle of Britain left their mark on past generations. I intend to journal the pandemic experience from three perspectives: as a retired medical technologist, as a historian (Ph.D., 2014), and an ordinary person living through an extraordinary world crisis.

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