If you're wondering how bad Delta really is, even in highly vaccinated SF (76% of >age 12 fully vaxxed) & still w/ a lot of masking (most folks in stores), we're seeing a pretty steep Covid uptick. Daily cases up 4-fold (10->42; Fig L), hospital pts doubled (9->19; R)(Thread 1/4) ImageImage
Uptick mirrored @UCSFHospitals: Covid inpatients (we were at ~3 pts two-wks ago) now 13 (Fig L). Overall test positivity rate was well below 1%; it's now up to 2.6% (Fig R). Even more worrisome, test positivity rate in asymptomatic pts was ~0.15%, now up 6-fold to 0.9%. (2/4) ImageImage
I don't have vaccinated/unvaxxed breakdown for SF & UCSF – I assume most severe cases are in unvaxxed. But even for vaxxed, w/ more Covid in air expect more breakthru cases. As for me, I'm back to double-mask in stores. Still indoor dining but might abort if trends continue.(3/4)
The SF # s are still fairly low, & are cause for caution, not panic. But this kind of uptick in SF (U.S.'s vaccination leader) shows that Delta is very real – the places w/ much lower vax rates may well get clobbered. Alas, doesn't seem like there are many persuadables left.(4/4)

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More from @Bob_Wachter

Aug 12
Quick 🧵to update SF Covid situation:
If you’re still being careful in SF (as I am), good news is that cases are down by ~50% in last 2 months, now 244 cases/day, down from peak of 537 (Fig L). As usual, hospitalizations lagging (now 117), but starting to trend down (R). (1/4) ImageImage
@UCSFHospitals: 36 pts (6 ICU; ~50/50 “for” vs “with" Covid – Fig L). ⬇~30% in 2 mths; ⬇80% from Jan peak. Asymptomatic test pos. rate=3.6% (R); was ~6% 2 mths ago.
At 3.6%, in group of 20 asymptomatic folks, 52% would test pos – still pretty risky to unmask in big group.(2/4) ImageImage
SF case count translates to 26/100K/d, seemingly close to my indoor dining threshold (<10-20/100K/d).
Except I multiply today’s #’s by 5 to approximate true case rate (accounting for home testing), so ~125/100K/d. That's a lot of Covid around – I’m keeping mask on for now.(3/4)
Read 5 tweets
Aug 3
Making decisions about how cautious (or not) to be w/ Covid remains challenging. In this 🧵, I’ll describe my current approach.
For me, with today's #'s, I find there's only 1 tough call, though it’s clear that most folks disagree – they’ve ditched their masks & moved on. (1/25)
I don't criticize anyone’s choice to be less careful. For many people, the value of "normal" & ditching the mask outweighs their perceived risk of, and from, getting infected – particularly now that the risk of a severe case (in vaccinated/boosted people!) is very low. (2/25)
Yes, your decision not to mask DOES ⬆risk to others around you. But we're now are able to keep ourselves protected via our own choices, which makes masking an individual risk-benefit decision. This wasn’t true in the pre-vax, pre-N95 era (thus, the need for mandates then).(3/25)
Read 25 tweets
Jul 21
Few quick thoughts re: @POTUS's Covid:
1) Not clear where he got it – he returned from Middle East ~3 days before test +, so probably last day of trip or flight home. Flying is low, not zero, risk, particularly if people weren't wearing masks. (1/13)
2) BA.5 is so transmissible that precautions that worked before may not prevent infection today. It seems like most of the country has "moved on", but if you're still trying to dodge the virus (as I am), need to up your game (ie, KN95 rather than surgical mask). (2/13)
3) Risk is related to both transmissibility of virus and probability of contact with person with Covid. Prevalence is so high now that you have to assume exposure in large indoor crowd. (Washington DC currently 29 cases/100K/d; it's probably 5-10x that due to home testing).(3/13)
Read 13 tweets
Jul 4
Covid (@UCSF) Chronicles, Day 838
The die is now cast: BA.5 is destined to be our dominant virus.
In today’s 🧵I discuss the implications on the course of the pandemic, and how to think about responding.
(I use “BA.5” & not “BA.4/5” since BA.5 is poised to outrun BA.4.). (1/25)
For the science & epi of BA.5, I encourage you to read @EricTopol’s terrific @SubstackInc review. erictopol.substack.com/p/the-ba5-story

We’ve now gotten used to Omicron sub-variants – each about 20% more infectious than the prior one – and so it’s easy to be lulled into thinking… (2/25)
… that BA.5 is just another one. But, as Topol describes, BA.5 is a different beast, with a new superpower: enough alteration in the spike protein that immunity from either prior vax or prior Omicron infection (incl. recent infection) doesn’t offer much protection. Drat. (3/25)
Read 25 tweets
Jun 13
Covid (@UCSF) Chronicles, Day 848
It’s been a few weeks since my last update – the flow of Covid news & research has slowed a bit. But there’s still plenty of questions that come up, so in this🧵I’ll answer a few that I get asked commonly, including how my wife is doing. (1/25)
Many people ask how my wife @katiehafner fared after her Covid case – we truly appreciate the concern.
The answer is: not great. Now 5 weeks post-infection, Katie has pretty bad fatigue, some brain fog, & periodic headaches. So, according to the most common definition of…(2/25)
…Post-Acute Sequelae of SARS-CoV-2 (PASC) (AKA, Long Covid), she now has it (though @WHO criteria is >2 months of symptoms).
Whatever the definition, it sucks – she’s an amazingly high energy person, & now she's wiped out most afternoons.

What have we learned about LC? (3/25)
Read 25 tweets
May 24
I was asked by a reporter today if I’d take Paxlovid if I had Covid. Last month, this would have been easy: as a 64-year-old person w/ asthma, the answer was an unequivocal YES.
Today, it’s a closer call – in this🧵I’ll lay out the reasons why, and then give you my answer.(1/25)
First, an update on my wife @katiehafner's Paxlovid rebound:
Katie finally tested negative yesterday, so her chronology is:
Pos for 8 days
Neg for 4 days
Pos for 5 days
Now negative & feeling better. (Hopefully it'll stay that way; I haven’t heard of double rebounds). (2/25)
Katie’s rebound involved not only reversion to a positive test (& 5 more days of strict isolation waiting for return of neg test) but an⬆in symptoms, mostly fatigue (now improving).
In my Twitter poll last week , 45% reported that they had rebound…(3/25)
Read 25 tweets

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