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Roby Bhattacharyya is also @roby-b.bsky.social Profile picture
Roby Bhattacharyya is also @roby-b.bsky.social
@roby_bhatt
ID doc @mgh_id, PI @broadinstitute. COVID, abx resistance resister. Hubby @megsise, Dad. Here to learn. Views mine. | https://t.co/cJ6awMmLBM | @roby-b.bsky
Mar 16, 2023 • 5 tweets • 2 min read
In case anyone's curious, I (an ID doc & voracious reader of COVID primary lit) signed my 4 yo kid (Pfizer x3 Jun-Sep 2022, never infected afaik) up for this bivalent booster. My main reason for primary series in him was to reduce tail risk of severe disease; this was different. I see a primary vax series in an uninfected person of any age as a slam dunk. COVID was a top 10 cause of death in each age group 2020-22. Vaccines reduce risk of death by >90%. Easy call. (I know other countries have different policies for kids. I disagree, esp for uninfected.)
Dec 17, 2022 • 15 tweets • 4 min read
Two papers this month w outcomes data for BA.5 bivalent booster:
- 30-50% effective vs symptomatic infection
- 73% effective vs hospitalization in those >65 yo (!)

In both cases *compared with ppl already 2-3x vaccinated, many w prior infection*!

BOOST UP!

Brief thread (1/11): 2/11
Study 1 (from early Dec): 360k outpts w/ respiratory infxn were tested for COVID (120k tested +). Those w bivalent (OG/BA.5) boost were less likely to test +, with vaccine efficacy of ~30% if prior dose was 2-3 mo ago, and ~50% if ≥8 mo ago.

cdc.gov/mmwr/volumes/7…
Dec 15, 2022 • 7 tweets • 3 min read
As I ponder whether to stay #onhere: can you share some tweets that changed how you view the world?

I'll start w one that pushed me faster than I otherwise would have towards a full embrace of open science:

If you're game, add yours to the thread below. Ground rules:
1. tweets only, not links to papers/articles (those are an important function of twitter, but I've been surprised how much 280 characters can say)
2. not your own
3. pix OK
4. 🧵s OK
4a. "if you liked this 🧵 please retweet & follow" 🧵s discouraged
Oct 30, 2022 • 8 tweets • 3 min read
Seeing resurgent claims that ventilators somehow killed people early in the pandemic. As best I can tell, this traces back to one JAMA paper that was badly misinterpreted, to the point that a correction was published 2 days later. Here's a slide from a talk I gave in May 2020. 1/ Original text: "88% mortality". Revised: "25% Here's the paper (Apr 22): jamanetwork.com/journals/jama/…

And the correction (Apr 24): jamanetwork.com/journals/jama/…

I'll explain in case anyone still cares: authors rushed to publish NYC outcomes (👏🏽). Only pts either discharged or dead were adjudicated, & median f/u was only 4.5 days! 2/
Jun 19, 2022 • 21 tweets • 6 min read
Finally read all 4 FDA briefing docs on u5/u6 vax's. 🧵 on how I'm thinking about each, as an ID doc (adult, not pedi), dad of a 4yo, & close reader of primary COVID lit.

tldr:
- Mrna: ⬆️ efficacy sooner
- Pf: ⬇️ side fx, ⬆️ certainty re dose 3, ⬆️ safety info in kids 5-17

1/16 2/16
Efficacy data is fraught bc Omicron makes efficacy against any infection a challenging goal. But per observational data over past 6 mo, vaccines w comparable efficacy in observational studies (~40% vs symptomatic infection) remain tremendously helpful vs Omicron (see plots).
Apr 2, 2022 • 20 tweets • 7 min read
Reviewed a few preprints on BA.2 immune evasion for a talk. My synthesis:
- BA.1 & BA.2 show similar immune escape from vax
- BA.2 is about as far from BA.1, antigenically, as Beta was from WT
- ppl w prior immunity, then BA.1 infxn, neutralize BA.1 & BA.2 ~equally well

Nerdy 🧵 2/6
 I like the "antigenic cartography" model for the variants (medrxiv.org/content/10.110…); I see BA.1 & BA.2 as ~ "antigenically equidistant" from ancestral spike, but kinda far from each other too, similar to the cloud of pre-Omi variants.

But, immunity is complex at this point…
Mar 11, 2022 • 18 tweets • 5 min read
2 studies out this wk on masks in schools. One 9-state tour-de-force on transmission, another in Arkansas comparing before & after mask mandates for students & teachers. Both show assoc b/w school mask mandates & ⬇️ COVID spread; the AR one (& physics…) suggest causality. 🧵 1/8 2/8
 Starting w AR study bc I like the time-series analysis (cdc.gov/mmwr/volumes/7…): more cases in schools than local communities, but less so in schools w mask mandates. OK, but that could be bc those schools were also more cautious in general. That's where time-series comes in
Feb 2, 2022 • 5 tweets • 3 min read
This perspective on Omicron's intrinsic severity just out in @NEJM. Pleasure writing with @BillHanage.

nejm.org/doi/full/10.10…

Summary 🧵 below still applies (but the Fig is way prettier now, & writing clearer, thx to NEJM!).

cc @mgh_id @broadinstitute @CCDD_HSPH An aside: I just started on service, so no time now, but I'm tempted to write a thread later abt my first time being so thoroughly copy-edited. Seriously eye-opening: I'm not sure a single sentence from the original escaped unscathed. (Lmk if you're interested in such a thing.)
Jan 16, 2022 • 4 tweets • 2 min read
Fig 2 from this paper on risk of myocarditis after Moderna vs COVID in men < 40 omits myocarditis Dx on same day as COVID (only plots d1-28 after vax/Dx). But on d0 (day of Dx) risk was 33x baseline w COVID (no incr risk w vax) - many are Dx'd w COVID & myocarditis on admission. It also doesn't count MIS-C/A myocarditis. So it understates risk from COVID myocarditis, even in this age group. Also, myocarditis from COVID is likely worse on average than from vax.

And COVID has many other risks beyond myocarditis; vaccines less so.

Jan 13, 2022 • 4 tweets • 1 min read
Haven't even read the thread yet but when @jameshay218 tweets about cycle thresholds, I pay attention Update: I've read the thread, but he summarized it better than I can :-)
Dec 26, 2021 • 9 tweets • 3 min read
Wow, this thread got more traction than I expected for a wonky summary of a complex (but important) study.

For those saying it brushes off milder societal impacts, I thought I'd try once more to clarify why I've been so insistent on unpacking intrinsic severity.

meta-🧵 1/9 2/9
 First: seems clear that, *per-case*, Omicron will be less damaging than prior waves. This is mostly b/c our society has more immunity to SARS-CoV-2 than ever before.

That's great news! But it doesn't tell us abt intrinsic severity of the virus. And we'll see many more cases.
Dec 24, 2021 • 14 tweets • 4 min read
Multiple studies this wk on rel severity of Omi vs Delta. IMO the Imperial College report best distinguished intrinsic severity from prior immunity.

tl;dr:
- O ~25% less severe than D
- but more transmission
- & prob more severe than other variants (incl its ancestor)
🧵 1/14 2/14
The report: imperial.ac.uk/media/imperial…

Challenges in estimating intrinsic severity:
- most ppl have some immunity by now (vax &/or past infxn) & thus will get less sick. This is good! But means comps to past waves are fraught: less population immunity then = more severe cases
Dec 15, 2021 • 9 tweets • 3 min read
Is Omicron intrinsically less severe than other variants? @BillHanage and I argue that it's still too early to say, despite what appear to be early signs of milder impact in SA than past waves.

Much of our case comes down to this figure

Preprint: cdn1.sph.harvard.edu/wp-content/upl…

🧵 1/9 2/9
 I (& many others) have previously pointed to various reasons why ascertaining intrinsic severity, as important as it is, will be hard for Omicron, & take careful work.

In the piece linked above, Bill & I explore the effect of immunity in more detail.
Dec 14, 2021 • 4 tweets • 2 min read
Valuable 🧵 w early observational data on Pfizer/BNT vax vs Omicron in SA:
- VE, 2 doses: ~30% vs cases, ~70% vs hosp (better in younger = more recent vax)
- severity: ~30% less in adults (w/ immunity), ~20% more in kids than D614G

Want data on boosters? Send boosters to SA. 🌍 Caveats (1/2):
- historical controls for severity are hard; many features of illness change w/ time (incl % of cases detected)
- still too early to infer intrinsic severity, but more hosp in kids c/w a slightly more severe *virus* than original (D614G) in a less-immune population
Dec 5, 2021 • 7 tweets • 3 min read
Little to add to this nuanced dissection of an important report from Steve Biko/Tshwane district hospital complex in Pretoria, reporting mostly mild cases (samrc.ac.za/news/tshwane-d…)

Agree it's too early to conclude much.

But imo there's some hidden good news abt kids 🤞🏽

🧵 1/6 2/6 One thing from SA that puzzled me: kids reportedly made up a startling % of COVID admissions this wave. But Tshwane report says in the majority of pts "SARS-CoV-2 has been an incidental finding in pts admitted to the hospital for another medical, surgical or obstetric reason"
Dec 2, 2021 • 4 tweets • 1 min read
A few thoughts on why I expect relative severity of Omicron to be the hardest of the Big 3 Q's (relative transmissibility; vax efficacy; severity) to answer w confidence:

1. Time lags
2. Case ascertainment
3. Effects of age, prior immunity (vax or infxn)
4. Rapid sweep

🧵 1/4 2/4
 (1) Time lags: well explained in this great thread:

(2) Case ascertainment: if SA looks harder for cases w/ the eyes of the world on them, they'll find more mild cases than in prior waves, which artifactually reduces % hosp even if severity constant.
Oct 14, 2021 • 17 tweets • 9 min read
Long overdue 🧵 on a COVID study we preprinted last year, now out in JID. Co-led by @nialljlennon @gabriel_stacey @eric_lander, enabled by @BroadGenomics & @MassDPH

Key finding: shed viral load is independent of symptoms at time of testing (pre-vax)

academic.oup.com/jid/advance-ar…

1/n 2/14
Back in Apr 2020, COVID overwhelmed our hospital in MA (I was on service & will never forget).


It also swept thru nursing homes, so @MassDPH tested ALL residents+staff of SNFs for COVID (back when tests were rare: big job w help from MA Nat'l Guard).
Oct 13, 2021 • 5 tweets • 3 min read
Nice interplay of threads from experts on a key question: what will the future of COVID bring? Nobody knows for sure, but @trvrb and @WhitneyEpi discuss some key factors on the viral and human/societal sides, respectively. Both 🧵's worth a read in full, but my tl;drs follow. 1/5 2/5 1st, @trvrb says:
- SARS-CoV-2 is here to stay
- more contagious at baseline than flu = prob larger annual infection footprint
- key unknowns that'll affect impact: rates of waning immunity & antigenic drift; severity of post-immunity infections (IFR)

Oct 1, 2021 • 11 tweets • 5 min read
Eyre et al (medrxiv.org/content/10.110…) is a tour-de-force. Bravo!
- traced 150k contacts from 100k cases (! - NHS👏🏽)
- Pfizer vax'd index cases had ~5x (Alpha) or 3x (Delta) lower odds of spreading (this is beyond protection by preventing the index case to begin with)
🧵 1/6 2/6
 - this despite similar cycle thresholds (Ct) in vax'd vs unvax'd index Delta cases, as others have shown
- Pfizer vax'd contacts had 16x (Alpha) or 10x (Delta) lower odds of being infected
- Ct is not infectivity
- Ct is not infectivity
- Ct is not infectivity
- #VaccinesWork
Dec 29, 2020 • 38 tweets • 15 min read
At the risk of shouting into the void, 🧵 on papers from 2020 that most changed how I think abt COVID, as an ID physician-scientist. 280-char summaries + URLs for each. Thx to all authors & apologies for any omissions; this list is unofficial, personal, idiosyncratic, & LONG. 1/ 2/ Early summary of 72,314 (hospitalized) cases from Chinese CDC, broken down by mild vs severe vs critical, early hint at CFR (overestimated b/c mild cases undersampled), & sharply age-dependent mortality. Also, risk to HCWs. Fig 1 (epidemic curve) key.

jamanetwork.com/journals/jama/…
Aug 6, 2020 • 9 tweets • 3 min read
NEJM editorial argues that low sensitivity tests are problematic
nejm.org/doi/full/10.10…

If the alternative is a perfect test, sure. But tests are still too scarce. We need more & faster tests; can sacrifice Se w/ clear communication

@michaelmina_lab @DanLarremore @RWalensky 🧵 2/8
 From the editorial: "A big concern has been test availability, but test accuracy may prove a larger long-term problem."

I disagree w this framing: the two features are in direct tension. If we hold out for "perfectly" sensitive tests, we resign ourselves to less testing.