Day: August 18, 2021

Why COVID/delta is so difficult to discuss

This tweet sparked quite a bit of discussion:

The short answer might be something like:

  1. Risk factors have changed..in a bad direction:

2. Delta CAN (and has) spread outdoors:

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Two recent studies have found that outdoor transmission of COVID could be more likely as the Delta variant continues to spread through the population. The first paper, which is still awaiting peer review, outlines a wedding in Texas in April. Even though the wedding was held outdoors under an open-air tent, an outbreak of the virus led to six fully vaccinated people becoming infected and one subsequently dying, Salon reports.

The authors point out two guests who had tested negative for the variant before traveling from India, but likely infected the other guests, who all later tested positive for the variant. They wrote: “With no histories of vaccine breakthrough, this suggests Delta variant may possess immune evasion in patients that received the Pfizer [vaccine], Moderna mRNA [vaccine], and [the] Covaxin [vaccine].”

The second case in question involves the Pendleton Whisky Music Fest, an outdoor concert held on July 10 in Oregon that has so far had 64 COVID infections connected to it. While it’s unclear how many of those who contracted the virus were vaccinated, state health officials launched an investigation into the event, saying in a press statement: “This outbreak is the first one of its size and scope to be traced to an outdoor entertainment event since the lifting of statewide COVID-19 prevention measures at the end of June.”

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3. Infections are increasing among the vaccinated.

Now as far as the science goes: true, most spread is via aerosols…indoor. But the delta variant is much more contagious and the outdoor spread is more like droplet spread.

So…these together means that “masking makes sense” in that situation.

But discussion…OMG… it is problematic because:

  1. Things change very rapidly. It was only weeks ago that mainstream articles declared that “breakthrough infections are rare.” (pre delta articles). So, someone who is reasonably well read might have bad information.
  2. Conditional probability is hard for some to grasp. Example: a few weeks ago, it was said that there were 1400 deaths out of 125K breakthrough infections. That is 1.1 percent..similar to the 1.7 percent overall. But that was conditioned on having a breakthrough, and it is a reasonable conjecture that the elderly and more immunocompromised might be more prone to breakthroughs.

    Or, when the NYT released an article that vaxxed people could spread it as easily as vaccinated ones, that was, yes, conditioned on being infected to begin with and the best current data I’ve seen would indicate that a unvaccinated person is 9 times more likely to become infected to begin with.
  3. Mitigation is hard for some to understand. “you might need a mask even if vaccinated” means, to them “oh, vaccinations don’t work?” Or: “X got infected though they were masked” means “your mask doesn’t work?” Risk REDUCTION is the goal; risk ELIMINATION is impossible.

And so…discussion is often confused and frustrating, even when talking to others in good faith..even when the others are neither evil nor stupid.