The mRNA from COVID vaccines primarily stays local at the injection site and its draining lymph nodes. I understand why this has become controversial and confusing. There's a lot of scary information out there. I'll try to clarify a few things: 🧵 2/

In vaccine biology, "local" means the injection site muscle and the lymph nodes that drain it (your armpit for a shoulder shot). That's where vaccines are designed to work.

Regulatory studies confirm this: highest concentrations remain at the injection site. Small amounts reach the liver briefly. Brain shows only trace amounts in animal studies. The vast majority stays local.

1/ Two days of ACIP chaos: Self-described "rookies" eliminated universal COVID vaccine recommendations, added FDA-debunked theories to consent forms, and voted outside their legal authority. They literally don't know what they're doing or what they're allowed to do.🧵 2/ The damage goes beyond specific votes. They normalized treating misrepresented lab findings without clinical context as equivalent to population-level safety data. ACIP voted to add "six risks and uncertainties" to COVID vaccine consent based on claims that FDA debunked in 2023, EMA rejected in 2025, and Australia's TGA called misinformation in 2024. They literally can't distinguish between actual safety signals and manufactured doubt.

The unpublished study presented at today’s Senate hearing contains fundamental methodological flaws that explain why it remains unpublished. Most notably: it confuses healthcare utilization with disease occurrence. 🧵analyzing the evidence: 2/ At today’s Senate hearing, Aaron Siri presented an unpublished Henry Ford Health System study as evidence that vaccines harm children. This analysis, reportedly completed in 2020, has never passed peer review. Understanding why requires examining its methodology.

The primary issue is detection bias. Vaccinated children in this study averaged 7 healthcare visits annually, while unvaccinated children averaged 2. This differential creates systematically more opportunities to diagnose and code conditions in the vaccinated group.

There's a myth that "vaccines were never tested against unvaccinated kids." This is false.

In fact, the original clinical trials for many childhood vaccines depended on this direct comparison.

We've documented several in our comprehensive vaccine RCT database. Let's look. 🧵

https://twitter.com/EvanMcFatridge/status/1964851909619278225

2/ MEASLES:

Study 1: Measles (UK, 1977, The Lancet)

This was a massive undertaking. Researchers followed ~5,000 children for 12 years. A single dose of the Schwarz measles vaccine was given to one group, while another concurrent group of children remained unvaccinated for direct comparison.

Key Finding: The vaccine provided a "high level of protection" that did not wane over the 12-year period. It also showed that breakthrough measles cases in the vaccinated were "less severe," proving a dual benefit of prevention and attenuation.
Link: pubmed.ncbi.nlm.nih.gov/71396/

Study 2: Measles (Poland, 1971, WHO Bulletin)

This controlled epidemiological study evaluated two measles vaccine strains against a dedicated, unvaccinated control group of children over 24 months.

Key Finding: They measured efficacy precisely, finding the Schwarz vaccine was 95.1% effective at preventing measles compared to the unvaccinated group. This high efficacy was directly linked to a 97% rate of seroconversion (antibody development) in the vaccine recipients.
Link: pubmed.ncbi.nlm.nih.gov/5316912/

@SecKennedy says he "reviewed the science" before terminating 22 mRNA vaccine projects worth $500M.

The "data" cited? 181 pages of cherry-picked lab studies ignoring all the high-quality evidence.

The US government is citing this as its scientific basis, which is outrageous:🧵 2/ This compilation is now the official basis for ending federal funding for Nobel Prize-winning technology that has averted millions of deaths.

I've been analyzing COVID vaccine safety data since the beginning. I reviewed what @HHSGov refers to has the "science."

Here's what's actually in it - and what's missing. jamanetwork.com/journals/jama-…

RFK Jr. is misrepresenting a landmark Danish study that followed 1.2 million children over 24 years. The study found no link between aluminum in vaccines and autism or neurodevelopmental harm. Let’s fact-check his claims - using actual data. 🧵

https://twitter.com/SecKennedy/status/1951423851314946083

2/ This study represents gold-standard epidemiological research. Over 24 years, researchers tracked 1.2 million children across 50 health outcomes. Edward Belongia, leading vaccine safety expert: "the largest and most definitive observational study on the safety of vaccine-related aluminum exposure in children" ever conducted. pubmed.ncbi.nlm.nih.gov/40658954/

As an infectious diseases physician and vaccine specialist, I need to address several serious misrepresentations, baseless assertions, and factual errors in this post. 🧵

https://twitter.com/RWMaloneMD/status/1945389226931183689

1/ Calling mRNA vaccines “genetic ‘vaccine’ products,” with “vaccine” in quotes, is a deliberate rhetorical move that undermines their legitimacy.

These are real vaccines by every scientific and regulatory standard. They generate protective immunity, prevent severe disease, and have saved millions of lives. The mRNA remains in the cytoplasm, never enters the nucleus, and is rapidly degraded within hours, providing temporary instructions for cells to make a harmless viral protein that stimulates protection. cdc.gov/covid/vaccines…

If anyone claims vaccines haven’t been properly studied, show them this:

We’ve now logged 500 randomized, controlled vaccine trials into our dataset with ~7.2M participants. The vast majority of trials reported safety outcomes. Many more trials to come.
bit.ly/4le8z7D Huge thanks to the inspiration and co-leader of the project, @BradSpellberg, and to our amazing team of volunteers who have been putting many hours into this - @AliSMV7, @alejodiaz81, @DhandAbhay, @ThePharmFox, @zacroBID, @TravisBNielsen, Dr. Matthew Phillips, @SarahRawi1, @IDwithNWD, Dr. Kusha Davar, Dr. Devin Clark, and countless anonymous contributors.

1/ Tucker Carlson: “Do you think overall the COVID vaccine killed more people than it saved?”
RFK Jr: “The truth is, I don’t know.”

This is outrageous.
I do know.
The answer is: unequivocally no. 🧵 2/ RFK Jr then added:

“And the reason I don't know is because the studies that were done by my agency were sub-standard, and they were not designed to answer that question."

I cared for hundreds of COVID patients and watched far too many die - including young, relatively healthy adults who never had a chance to get vaccinated, or who declined it.

And I’ve reviewed the evidence. Many of the studies he’s dismissing are anything but “sub-standard.”

It’s not even close.

This claim about the Amish deserves correction with actual data. 🧵

https://twitter.com/rwmalonemd/status/1939373583823995361

2/ Research shows that many Amish families do vaccinate their children. Studies find that anywhere from 41% to 85% of Amish parents have vaccinated at least some of their children, depending on the community and time period.

RFK Jr's thimerosal thread is a masterclass in misinformation. Let's fact-check it line by line. 🧵 2/ CLAIM: “There are high bolus doses of mercury in flu shots.”

FACT: 96% of flu vaccines are thimerosal-free.
Multi-dose vials contain 25 mcg per dose. That’s not a “high bolus.”
fda.gov/vaccines-blood…

It’s not easy to navigate the maelstrom of misinformation. Grateful to @megtirrell and @boulware_dr for cutting through it.

Slides prepared for ACIP this week by former CHD leader Lyn Redwood cited a 2008 Neurotoxicology study on thimerosal and “long-term brain harm.”

But the study doesn’t exist. The listed author says he never wrote it and his actual research found no such effect.

Debates should be grounded in evidence, not phantom citations.

Thimerosal has been thoroughly studied for decades. Here's what the evidence actually shows🧵👇
cnn.com/2025/06/24/hea… 2/ What the evidence actually says

Thimerosal has been used in vaccines and biologics since the 1930s. It’s highly effective at killing bacteria and preventing contamination, especially in opened multi-dose vials.

Thimerosal contains ethylmercury, not methylmercury. Ethylmercury is broken down and excreted quickly; unlike methylmercury, it doesn’t build up or persist in the body.

In 1999, U.S. health agencies recommended removing thimerosal from childhood vaccines as a precaution, not because of evidence of harm. By 2003, all thimerosal-containing pediatric vaccines (except some flu shots) had expired. pubmed.ncbi.nlm.nih.gov/10418806/

It’s understandable to have questions about aluminum in vaccines. Here are the key facts:
🧵 1⃣ Why is aluminum there?

A tiny amount of aluminum salt acts as an adjuvant - a helper that tells your immune system, “Pay attention!” This lets the vaccine work better with less antigen (the piece of virus or bacteria that trains immunity). In this sense, it's dose-sparing: less antigen per shot.

RFK Jr. went on national TV and spouted egregious, dangerous falsehoods about vaccines. As a parent and infectious diseases doctor, I couldn't stay silent. @FoxNews might not fact-check him, but I will. I've reviewed the trials. I've catalogued them. I have receipts. 🧵

https://twitter.com/atrupar/status/1933254404519469135

❌CLAIM 1: "97% of people on [ACIP] had conflicts of interest"

✅REALITY: Only 41% received any industry payments, mostly under $55k over 6 years
This is flatly false. Reuters reviewed all 17 voting members of the outgoing ACIP panel:
6 received $80 or less TOTAL over 6 years

7 received between $4k-$55k total over 6 years (mostly travel, meals, occasional consulting)
4 had no reported industry payments at all
That's 7/17 = 41%. Not 97%.

CDC rules require recusal for any vote tied to a relevant conflict. Meeting minutes show ONE recusal in the reviewed period.
ACIP members are unpaid volunteer experts. They don't get royalties, don't keep pharma stock, don't get flown to golf courses.
A published review found <5% of ACIP votes over the past decade involved a declared conflict.
reuters.com/business/healt…

I’ve been getting a lot of questions about what it really means for a vaccine trial to be “placebo-controlled” - and how that differs from other control groups.

It’s a great question, and clarity here really matters.

Let’s break it down. 🧵

CC @EricTopol @angie_rasmussen @PeterHotez @trvrb 3 control types:

1. Placebo (saline/inert)

2. Active comparator (e.g., alum-only or licensed vax)

3. No-intervention (observed only)

2/

“White lung syndrome” is a made-up term. Any pneumonia appears as a white opacity on an x-ray or CT, which is partly how the diagnosis of pneumonia is made. But it’s not specific to pneumonia, and it’s certainly not specific to Mycoplasma pneumoniae, which is not “mysterious”. 🧵 Mycoplasma pneumoniae is a bacterium, not a virus. (It’s one of the smallest free-living organisms.) It can cause pneumonia in kids age 5-17 and can be severe but is very uncommonly fatal. Radiographic findings vary but can look worse than anticipated from the physical signs. 2/3

Urinalyses (UAs) are widely used, yet are often ordered inappropriately, and the results are not as meaningful as one might think.

Pyuria (WBCs in urine) is nonspecific (although the absence of pyuria should call into question a diagnosis of UTI).
🧵
1/5 Leukocyte esterase is a screening test for pyuria (see above).

Hematuria can occur in patients with UTIs, but is also not specific, and generally doesn’t change management. (If there are clinical signs of obstructive pyelo in a patient with sepsis, check a noncontrast CT.)

2/5

I disagree with this statement:

“…protection against severe disease may only last about four to six months.”

I think that the vast majority of people can expect protection against severe COVID-19 to last much longer than 6 months. 🧵
1/

npr.org/sections/healt… As I’ve previously mentioned, accurately determining the duration of vaccine-induced immune protection is challenging, for many reasons:

1. Many who were vaccinated earlier were at highest risk, which could confound results.

2/

Antibodies continue to get all the attention.

This @washingtonpost piece gives them too much credit, and leaves out the critical role of cellular immunity.

1/

washingtonpost.com/health/2023/01… The main reason why most people need not worry about severe illness caused by XBB.1.5 or any other Omicron subvariant is because non-neutralizing antibodies, memory B cells, & CD4+/CD8+ T cells provide longlasting protection against all variants to date.

onlinelibrary.wiley.com/doi/10.1111/im…

The Argentinian outbreak of pneumonia was found to be due to Legionnaire’s disease (caused by Legionella bacteria)

This was first recognized as the cause of the outbreak at the American Legion convention in Philadelphia in 1976, which affected 221 people and led to 34 deaths

https://twitter.com/Tuliodna/status/1566084754511912962

The American Legion outbreak went unsolved for months. Ultimately attributed to airborne spread of a bacterium. Exposure was environmental (not person-to-person) and may have occurred in the hotel lobby.

Legionella grow in warm water, cooling towers, plumbing, fountains, etc. 2/

This thread has gotten a lot of attention, but I think there are a few points worth highlighting:

1st: I’m glad Dr. Wachter’s son has recovered

2nd: I’m not surprised, because #VaccinesWork 🧵

https://twitter.com/bob_wachter/status/1479913165039095810

3rd: he states that his 28-yo 3x-vaxxed son is “moderately high-risk” because he’s “overweight.”

If he were *unvaccinated*, yes, being obese (especially if his BMI were ≥30, based on data from meta-analyses) increases the risk for severe outcomes.

bit.ly/3rnDFPM

2/