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Sunday, July 4, 2021

This morning we woke up to a headline heralding “California’s dominant coronavirus strain.” It sounds as though Delta is now in the majority of strains statewide. It’s not, but it just surged ahead of Alpha, the previous frontrunner. Looking at genomic sequencing data from the California Department of Public Health, the proportion of new cases identified as Delta variant has increased like this: March: None; April: 2.1%; May: 5.6%; June: 35.6%. In June, it gained the lead over the original variant for the first time.

California Department of Public Health

Delta infections have been found in all 50 states are increasing throughout the United States, notably in Missouri, Arkansas, Nevada, Colorado, and Utah.

  Missouri  has asked for federal aid as COVID strains its hospitals. Worldwide, Delta has been found in at least 85 countries, accounting for almost all the cases in India and the UK. It’s spreading rapidly in many countries, including Portugal, Israel, Russia, Indonesia, Iran, and South Africa.

Cases are increasing, but want does this mean? We know how the progression works now—more cases mean more illness, more hospitalizations, and more deaths. Most people who get infected (i.e. test positive) will not get very ill, but a small percentage of a large number is still a large number. Most of the people who contract the delta variant will feel fine and continue with their lives while spreading it around.

Does this matter, if they don’t feel sick? I’ve seen contradictory information about whether the Delta variant causes different or more serious disease than other strains or whether it can “break through” vaccine immunity or immunity from a previous infection. Examples of breakthrough infections in vaccinated individuals have been publicized, some of them serious, but so far this appears to be the exception rather than the rule.  Research on breakthrough cases is still ongoing. But even without definitive results about severity and susceptibility, we know one thing. It spreads fast.

Fast through the population, that is. The issue of how fast it spreads from person to person was brought into question when a report from Sidney, Australia, documented an example of spread from a “fleeting” encounter of 5-10 seconds contact with an infected individual. Until now, the expected exposure time for infection was said to be 10-15 minutes. More study is needed on this report, according to the WHO (article below).

Research in India suggests that Delta spreads more quickly than other variants through household members. The Los Angeles Times gave an example of clustered cases in Palmdale and Lancaster with fourteen cases of the Delta variant in one household. Household spread also needs more study, but in the meantime, we know one thing for sure. Delta is more contagious.

And this contagion is the problem. Delta spreads faster than the other variants we have known. The R0 number for Delta is 5-8, meaning one person infects 5-8 people on average, or about 40-60% more transmissible than the alpha variant. Not as fast as measles or mumps, but faster than the previous variant. One person spreads it to more of the people they contact. One person in a household, old or young, feeling sick or feeling fine, spreads it to the whole family.

Therefore we can expect:

  1. Increased variants. Viruses mutate as they multiply. Delta will lose its ascendency to a younger, faster strain. Will it make you sicker? Will it break through current immunity? Maybe, maybe not.
  2. Increased cases in non-immune populations—the young, the healthy, the unprotected–resulting in more hospitalizations and deaths.
  3. Increased incidence of “long COVID,” with its neurological effects and organ damage.

This is Delta’s day. It’s spinning off new variants even as we study its character. Yes, it matters.

Today’s Notable Headlines

“Infectious Delta variant spreads rapidly, now California’s dominant coronavirus strain,” Los Angeles Times, July 4, 2021. https://www.latimes.com/california/story/2021-07-04/delta-variant-spreads-rapidly-now-california-most-dominant-strain-coronavirus-covid-19

“5 states where the coronavirus delta variant is spreading, “ The Hill, July 2, 2021. https://thehill.com/policy/healthcare/561419-5-states-where-the-coronavirus-delta-variant-is-spreading

 “Missouri requests federal COVID aid as cases surge; Fourth of July travel raises concerns: Latest COVID-19 Updates,” USA Today, July 3, 2021. https://www.usatoday.com/story/news/nation/2021/07/03/fourth-july-travel-uptick-raises-covid-concerns/7847714002/

“Jury out on Delta variant ‘fleeting contact’, WHO says,” 9 News, June 26, 2021. https://www.9news.com.au/world/coronavirus-delta-variant-fleeting-contact-transmission-not-certain-who-says/561be8a1-8e49-49b2-97b1-a9108057b280

“Covid-19: Delta variant transmits more in households,” Times of India, June 12, 2021. https://timesofindia.indiatimes.com/city/hyderabad/delta-variant-transmits-more-in-households/articleshow/83445855.cms

“UK Covid LIVE: Delta variant has 60% increased risk of household transmission as cases double every four days,” Evening Standard, June 11, 2021. https://www.standard.co.uk/news/uk/coronavirus-latest-updates-ministers-consider-four-week-lockdown-reopening-delay-vaccine-g7-summit-b940018.html

Additional Sources:

California Department of Public Health https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/COVID-19/COVID-Variants.aspx

Image: Novel Coronavirus. NIAID.

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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