Eric Feigl-Ding Profile picture
Mar 2, 2021 20 tweets 9 min read Read on X
UNDERRATED BENEFITS of J&J vaccine on severe illness— lost in efficacy comparisons is how the J&J vaccine efficacy actually may **get better over time** for severe #COVID19–as high as 90-95% at 56 days—trend is very strong. And makes J&J on par w/ Pfizer-BioNTech & NIH-Moderna.🧵 Image
2) And do we see that in the table? Yes... in all countries, the efficacy of J&J vaccine against severe #COVID19 was always higher after 28 days than after 14 days: Rising from 70’s to mid-upper 80’s%.
fda.gov/media/146219/d… Image
3) Let’s look at the Pfizer-BioNTech vaccine for 14-27 days & severe #COVID19 outcome... it was just 62-80% for severe in Israel, on par if not lower than J&J. And for >35 days with 2nd shot? 92% against severe, on par with J&J that only used 1 shot without any booster. Image
4) Do we see J&J performing strong on hospitalization, ICU, mechanical ventilation? Yes. In fact, 28 days after vaccination with J&J, zero events, which means de facto 100% efficacy. Image
5) Also keep in mind the large number of variants during the more recent era of the J&J vaccine. 46-59% of all cases were variants. And 96% of the South Africa 🇿🇦 trial’s 59% cases that were variants - was the infamous #B1351 variant! Image
6) But wait, didn’t we just see the J&J vaccine being 64% efficacious overall and 81.7% efficacious against severe #COVID19 in South Africa 🇿🇦 after 28 days? YES!!!

That means the J&J vaccine is quite good even for the #B1351 variant that was 56% of all cases in SA! Image
7) Also, if we truly compare apples to apples on days since first shot, while the Pfizer vaccine showed 92% after 35 days (7 after 2nd booster)—yet J&J efficacy matched that range if average all of its efficacy range after its 35 days (with only 1 shot!) ImageImage
8) Furthermore, the J&J trial was done in a middle of the WORST SURGE periods in each country that implemented the J&J trial! What does this matter? In epidemiology, we call this high background rate—which can skew efficacy vs the Pfizer/Moderna trials with low rates—here is how: Image
9) Suppose Pfizer prevented 9 cases... 10 cases in placebo, 1 in vaccine—90% efficacy.

But if J&J was carried out when rates are high, then could be 20 cases in placebo, and 11 in J&J vaccinated—The efficacy is then 45%!

(This is what happens it yields absolute risk decrease)
10) So don’t be disappointed by the lesser 66% efficacy.... that is dragged m down by all the circumstances above (not J&J fault).

➡️Also don’t forget that if we prevent a severe case, that case then usually less severe right? EXACTLY—hence why we see J&J hugely lower symptoms! Image
11) Think of this analogy—if a drug or special diet prevents / treats obesity.... there will then be MORE moderate overweight people (only small reduction in overweight %)... But that is because tons of formerly obese dropped down to overweight category!!! here severe➡️moderate.
12) Going back to the high baseline rate issue of the J&J vaccine, I had laid out a situation above where absolute risk difference doesn’t change but RR did. Granted, but high background rate can weaken the RR too—e.g. much greater chance of stacked exposure doses & exposed load.
13) What I mean by that is—with high rates in community, a vaccinated person could get exposed a lot more & multiple times—greater virus dose and increasing chance of successful infection—if community rates high. This maybe also led to lower overall JJ efficacy. Image
14) Also was the Pfizer vaccine perfect for severe disease in the original FDA approval submission for EUA? No... after 2 doses... 35 days after first shot... it was ~75% against severe, and 88.9% against severe anytime after 1 shot. Par with J&J.
fda.gov/media/144245/d… Image
15) Johnson & Johnson vaccine deliveries nationwide begins today!!! #CovidVaccine #COVID19

(video: UPS center in Louisville, Kentucky)

16) To be clear, J&J matches Pfizer & Moderna on severe disease efficacy over time. But why do I think J&J is likely as good also for moderate/milder #COVID19 too? Because J&J was tested during the PEAK SURGE periods of countries. I explained reasons above, but here is analogy:
17) ANALOGY: Vaccines are like a chest body armor—they can block some bullets (virus attack) but they can’t block a large number of automatic machine gun bullets. Vaccines protect most of time, but sometimes mild infections can happen. But without armor, you’re very vulnerable...
18) But J&J was tested during a period of peak exposure and virus prevalence (constant barrage & multiple exposures, more dose), while Pfizer/Moderna trials were during more modest infection periods (fewer bullets to block, plus also fewer armor penetrating #B1351 variants).
19) Hence, J&J had more “armor failure” —because it was used during period of heavier bombardment than Pfizer/Moderna.

Meanwhile, placebo without any armor, any number of bullets can pierce your body.

That’s the theory speaking to folks folks. J&J likely just as good as mRNA.
20) They are testing a booster for J&J. The other two adenovirus vaccines by Oxford & by Russia - Sputnik V - have a 2nd shot. But just one shot is still very good. The increase in efficacy over time is quite strong (top post), but I won’t be surprised if they roll out boosters.

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More from @DrEricDing

Jun 16
📍 THE 17 FIRED MEMBERS OF CDC’s VACCINE ADVISORY COMMITTEE (ACIP) speak out…

📍“As former ACIP members, we are deeply concerned that these destabilizing decisions, made without clear rationale, may roll back the achievements of US immunization policy, impact people’s access to lifesaving vaccines, and ultimately put US families at risk of dangerous and preventable illnesses.” 🔥

Full text:

Vaccines are one of the greatest global public health achievements. Vaccine recommendations have been critical to the global eradication of smallpox and the elimination of polio, measles, rubella, and congenital rubella syndrome in the US. They have also dramatically decreased cases of hepatitis, meningitis, mumps, pertussis (whooping cough), pneumonia, tetanus, and varicella (chickenpox), and prevented cancers caused by hepatitis B virus and human papillomaviruses.1 Recent scientific advancements enabled the accelerated development, production, and evaluation of COVID-19 vaccines, leveraging novel technologies that are estimated to have prevented approximately 1.6 million hospitalizations and 235 000 deaths in the US alone.2
For more than 60 years, the Advisory Committee on Immunization Practices (ACIP)—codified in the federal regulations (42 USC 217a: advisory councils or committees)—has served as a panel of experts that reviews the most up-to-date evidence on vaccines and monoclonal antibodies (eg, against respiratory syncytial virus [RSV]), providing sound recommendations to the US Centers for Disease Control and Prevention (CDC) regarding how vaccines should be used. ACIP recommendations are the cornerstone of the immunization program in this country. First, they serve as guidance and are the national standard for the use of Food and Drug Administration (FDA) authorized and licensed vaccines, providing a unified and trusted approach to vaccinations for the diverse array of immunization providers across the US. Second, they ensure science-based and tested immunization schedules that are optimized for well-timed protection against serious diseases. Third, the recommendations affect insurance coverage and safeguard broad access for vaccines. Fourth, ACIP’s continued monitoring of disease epidemiology and scrutiny of vaccine safety inform timely updates to recommendations that have maintained the trust and protection of the population. This transparent and ongoing surveillance of vaccines is one of the most stringent around the world, historically making the deliberations and decisions of this committee a beacon for immunization programs globally, while also serving as the foundation for recommendations harmonized with leading medical organizations in the US.3,4
ACIP committee members have always been selected through a rigorous process based on their expertise in immunology, epidemiology, pediatrics, obstetrics, internal and family medicine, geriatrics, infectious diseases, and public health. Historically, committee members were chosen because they worked at hospitals, clinics, health departments, universities, and other organizations where they dedicated themselves to caring for patients, conducting research, and helping to prevent and treat infectious diseases. Members’ deep understanding of immunization issues ensured that vaccine policies were grounded in scientific evidence, aligned with the needs of economically, socially, and medically diverse US communities, and always considered the public value, trust, and acceptability of vaccines.
Despite recent suggestions to the contrary, health care providers and the US public trust ACIP. For the past 18 years, the National Immunization Survey has shown that 99 of every 100 children in the US have received at least some recommended vaccines by 2 years of age, consistent with acceptance of ACIP recommendations implemented by trusted clinicians (National Immunization Survey - Childof Healthy People 2030).…Image
2) Full text part 2:

This does not suggest the population is so distrustful that it warrants dismantling the process by which vaccines have been recommended. ACIP standard procedures have minimized the risk of alleged conflicts of interest and biases. For decades, members of ACIP have undergone a thorough application and review process to participate. Proposed members submitted letters of support from other known experts and peers, completed an interview process, underwent a background check, and disclosed financial interests that might be considered a conflict, including any professional or financial relationships of immediate family members. Historically, it has taken up to 2 years for nominees to be approved to join ACIP.
Once part of the committee, ACIP members spent significant time preparing for meetings, reviewing the scientific evidence, and chairing work groups that, along with many CDC public health officials, led to the final recommendations that were determined during public meetings, which also included opportunities for public comment. Recordings of these meetings, agendas, and presentations were publicly available. Additionally, members agreed to ongoing monitoring and disclosure throughout their tenure. For example, potential conflicts of interest were reviewed throughout their time on the committee. Statements about potential conflicts were required during each meeting and before each vote, and members recused themselves from voting if any conflicts were identified. These disclosures have also recently been posted on the CDC website for public scrutiny. ACIP was among the most stringent and transparent of the federal committees, and we hope those criteria will apply to any new members joining the committee.
The abrupt dismissal of the entire membership of the ACIP, along with its executive secretary, on June 9, 2025, the appointment of 8 new ACIP members just 2 days later, and the recent reduction of CDC staff dedicated to immunizations have left the US vaccine program critically weakened.5,6 These actions have stripped the program of the institutional knowledge and continuity that have been essential to its success over decades. Notably, the ACIP charter specifies that committee members serve overlapping terms to ensure continuity and avoid precisely the disruption that will now ensue. The termination of all members and its leadership in a single action undermines the committee’s capacity to operate effectively and efficiently, aside from raising questions about competence.
Compounding these concerns, recent changes to COVID-19 vaccine policy, made directly by the HHS secretary and released on social media, appear to have bypassed the standard, transparent, and evidence-based review process.7 Such actions reflect a troubling disregard for the scientific integrity that has historically guided US immunization strategy. The newly stated strategy to replace ACIP members with individuals who will “exercise independent judgment, refuse to serve as a rubber stamp, and foster a culture of critical inquiry” is already leading to warnings by academic and scientific institutions, professional organizations, and the public who for decades have known well that these sought-after qualities precisely characterized the now-dismissed members of the ACIP.5
3) Part 3:

As former ACIP members, we are deeply concerned that these destabilizing decisions, made without clear rationale, may roll back the achievements of US immunization policy, impact people’s access to lifesaving vaccines, and ultimately put US families at risk of dangerous and preventable illnesses. Vaccines and the anti-RSV monoclonal antibodies are lifesaving, and people in the US deserve to have recommendations and broad access to use them to prevent serious diseases. In this age of government efficiency, the US public needs to know that the routine vaccination of approximately 117 million children from 1994-2023 likely prevented around 508 million lifetime cases of illness, 32 million hospitalizations, and 1 129 000 deaths, at a net savings of $540 billion in direct costs and $2.7 trillion in societal costs.8Finally, as individuals, we remain committed to evidence-based vaccine policy, both through our ongoing work in immunization science, public health, and medical education, and by supporting future efforts to keep America healthy that uphold scientific rigor and the public’s trust.
Read 4 tweets
May 8
⚠️Tariffs On Medications Will Make America Sick

We might soon see the Trump WH impose tariffs on pharmaceuticals—patients will suffer and die.

During the past few weeks, President Trump’s on-again, off-again tariff wars have rattled the stock market, decimated many Americans’ retirement funds, and promised to send grocery prices soaring—and his administration hasn’t even gotten to critical pharmaceutical tariffs yet. But that will likely be the next shoe to drop.
Trump exempted pharmaceuticals from his first round of tariffs in early April, but recently declared that he intends to impose “a major tariff” on imported medicines “very shortly.” These tariffs, he claims, will prompt pharmaceutical companies to leave countries including China and India and begin “opening up their plants all over the place.”
Commerce Secretary Howard Lutnick said in a television interview in mid-April that these tariffs are coming in the “next month or two.”

What will this mean? 

Read on:
progressive.org/op-eds/tariffs…Image
2) The majority of brand name drugs used in the United States are imported. Even generic drugs often rely on ingredients and direct imports from China, including pain relievers and cardiovascular drugs used by millions.
3) The United States was already facing a drug shortage crisis before Trump’s tariff announcement. Now, his policies will drive upnot only the cost of medicines, but also other health care items such as X-ray machines and medical instruments.
Read 8 tweets
Apr 10
It’s a trap: CATCH 22—if you register, ICE will deport you. If you don’t register, you’ve now committed a crime for the first time, and ICE will deport you. Trump doesn’t care if you’ve paid all taxes and followed all laws—ICE will deport you.

apnews.com/article/illega…Image
2) The Department of Homeland Security announced that it was mandating that all people in the United States illegally register with the federal government, and said those who didn’t self-report could face fines or prosecution. ***Failure to register is considered a crime***
3) Registration will be mandatory for everyone 14 and older without legal status. People registering have to provide their fingerprints and address, and parents and guardians of anyone under age 14 must ensure they registered. The registration process also applies to Canadians who are in the U.S. for more than 30 days, such as so-called snowbirds who spend winter months in places like Florida.
Read 4 tweets
Apr 3
Now economists know how scientists felt back when he pushed “hydroxychloroquine”
2) HCQ preventing COVID deaths has been debunked— and it’s now been linked with deaths.

@JoshuaPCohen1
forbes.com/sites/joshuaco…Image
@JoshuaPCohen1 3) JPMorgan on Trump Tariffs: “The largest tax increase since 1968” Image
Read 6 tweets
Mar 28
My god—Earthquake (a Richter ~7.7) causes a skyscraper to collapse in Bangkok. Hope all the construction workers made it out.
2) this skyscraper collapse was captured from a distant car’s dashcam while on a highway

3) another view of the collapse. For those who lived through 9/11, this collapse is a bit triggering.
Read 5 tweets
Mar 27
Welp—kiss public health & medical research infrastructure in America goodbye for the next 4 years. RFK Jr plans to cut 10,000 jobs from Trump HHS. Image
2) this will not make America healthy again… not by a long shot. So dangerous and irresponsible.
3) “Kennedy is set to announce Thursday the planned changes, which include axing 10,000 full-time employees spread across departments tasked with responding to disease outbreaks, approving new drugs, providing insurance for the poorest Americans and more”.
Read 5 tweets

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