Saturday, August 14, 2021

'Pandemic of the unvaccinated' narrative falling flat

Don’t Panic, But Breakthrough Cases May Be a Bigger Problem Than You’ve Been Told Current public-health messaging may understate the scale and risk. | New York Magazine - David Wallace-Wells, Intelligencer:

August 12, 2021 - "''Breakthrough' sounds bad — implying an immune-escape mutation, likely rare, and therefore alarming. The vaccines were never tested to prevent transmission, only symptomatic disease, and those who knew the science expected, from the outset, that we would see some number of such cases, and that they would be, overwhelmingly, mild. But Delta appears to have changed things....

"Over the last few weeks, in the wake of an attention-getting internal CDC presentation on the severity of the current wave, we’ve heard a lot ... about how ... vaccines were working, that breakthrough cases remained rare and mild, that the pandemic was now largely a pandemic of the unvaccinated. On July 30, the Kaiser Family Foundation ... declared that the relative risk to the vaccinated of infection, hospitalization, and death was close to — or mathematically equal to — zero, and that in almost all states only about 1 percent of identified cases were breakthrough events. This reading was echoed by the later Times analysis, and itself echoed earlier, reassuring statements by Anthony Fauci, that 99.2 percent of deaths in June were in unvaccinated people, and Surgeon General Vivek Murthy, that, as of July 18, '99.5 percent of COVID deaths are among the unvaccinated'....

"The current, bleak Delta wave is being driven primarily by cases in the unvaccinated, and the best tool in attacking the pandemic is more vaccination.... But nevertheless a closer look at the data reveals that some of the public health communication may be overstating the vaccine effect on transmission and understating the scale and risk of breakthrough infections, which, while far from predominant, do appear prevalent enough to be helping shape the course of the disease.

"'The message that breakthrough cases are exceedingly rare and that you don’t have to worry about them if you’re vaccinated — that this is only an epidemic of the unvaccinated — that message is falling flat,' Harvard epidemiologist Michael Mina told me.... 'If this was still Alpha, sure. But with Delta, plenty of people are getting sick. Plenty of transmission is going on. And my personal opinion is that the whole notion of herd immunity from two vaccine shots is flying out the window very quickly with this new variant.'

"'We’re seeing a lot more spread in vaccinated people,' agreed Scripp’s Eric Topol, who estimated that the vaccines’ efficacy against symptomatic transmission, which he estimated to be 90 percent or above for the wild-type strain and all previous variants, had fallen to about 60 percent for Delta. 'That’s a big drop.' Later, he suggested it might have fallen to 50 percent, and that new data about to be published in the U.S. would suggest an even lower rate. On Wednesday, a large pre-print study published by the Mayo clinic suggested the efficacy against infection had fallen as far as 42%.

“'The breakthrough problem is much more concerning than what our public officials have transmitted,' Topol continued.... 'I think the problem we have is people — whether it’s the CDC or the people that are doing the briefings — their big concern is, they just want to get vaccinations up. And they don’t want to punch any holes in the story about vaccines. But we can handle the truth. And that’s what we should be getting'....

"The central distortion reflected in the Kaiser report — and echoed by communicators elsewhere, including in the Times — is the result of a basic error of comparison ... using year-to-date 2021 data, which include several months before mass vaccination (when by definition vanishingly few breakthrough cases could have occurred) during which time the vast majority of the year’s total cases and deaths took place (during the winter surge).... And because those first few, brutal months of the year were exceptional ones, do not reflect anything like the present state of vaccination or the disease, they throw off the ratios even further. Two thirds of 2021 cases and 80 percent of deaths came before April 1, when only 15 percent of the country was fully vaccinated, which means calculating year-to-date ratios means possibly underestimating the prevalence of breakthrough cases by a factor of three and breakthrough deaths by a factor of five.

"Unfortunately, more accurate month-to-month data is hard to assemble — because the CDC stopped tracking most breakthrough cases in early May, before the Delta wave had begun, and the states maintaining their own databases often update them irregularly and, in some cases, according to idiosyncratic logic — but over the last week, I’ve tried. [S]everal states show prevalence rates roughly in line with Kaiser’s ballpark 1 percent estimate (in Virginia, for instance, breakthroughs represent 2.3 percent of new cases and 5.2 percent of deaths).... In Delaware, between July 1 and July 22, 'breakthrough' cases were 13.8 percent of the total. In Michigan, between June 15 and July 30, the figure was 19.1 percent. In Utah, 8 percent of new cases were breakthroughs in early June, but by late July, as Delta grew, the share grew, too, to 20 percent (even while the total number of cases almost doubled). According to those leaked CDC documents, there were, as of late last month, 35,000 symptomatic breakthrough cases being recorded each week — about ten percent of the country’s total....

"The 125,000 known U.S. breakthrough cases through the end of July represent, according to NBC News, only 0.08 percent of the vaccinated population — meaning that less than one-tenth of one percent of all vaccinated people have gotten a confirmed breakthrough infection. That is encouraging, and impressive, and reassuring. But less than one percent of the unvaccinated got a confirmed case in July, either.... In California, for the week ending July 31, the average case rate among the unvaccinated, the state reported, was 33 per 100,000, while the average daily case rate among the vaccinated was 7 per 100,000 — a five-fold decrease, more or less. That’s still very good! But five-fold or ten-fold is not the hundred-fold reduction implied by Kaiser, Fauci, or Murthy."

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