- 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. @bradspellberg.bsky.social @adamlauring.bsky.social #IDsky
- 3 control types: 1. Placebo (saline/inert) 2. Active comparator (e.g., alum-only or licensed vax) 3. No-intervention (observed only) 2/
- Placebo Used when no licensed vax exists & ethics allow. Peru cholera ’99: 85 % VE vs saline 3/ pubmed.ncbi.nlm.nih.gov/10569747/
May 7, 2025 18:50
- Active comparator When a proven vax exists you can’t ethically withhold it. Gardasil vs alum-only maintained blinding & isolated HPV antigen effects 4/ pubmed.ncbi.nlm.nih.gov/17494926/
- No-intervention Kendrick & Eldering whole-cell pertussis, 1934–38 (TN, 5,815 kids): controlled, non-randomized, ~86 % VE - genuine “no shot.” 5/ www.jameslindlibrary.org/kendrick-p-e...
- Why it matters: Mis-labelling every control as “placebo” blurs ethics & evidence - and lets critics claim “vaccines weren’t tested against saline.” In reality, most modern trials, incl. pre-licensure COVID-19 RCTs, were classic saline-placebo studies. 6/
- What our sheet shows: 103 trials (3 duplicate tetanus rows merged) 1, 791,082 participants 77 % placebo 19 % active 4 % none 7/ Sheet: www.bradspellberg.com/vaccine-rcts
- Share this thread to counter misinformation. Crowd-sourced. No industry $. Quiet work ➡️ shared truth. Help us keep building it. docs.google.com/spreadsheets...
- No-intervention = no control shot. Pre-1950s field trials used it when blinding norms were new, giving saline to 100k+ kids was impractical, and endpoints were hard (paralysis, death). Salk ’55 mixed no-shot & saline arms - still controlled, but higher bias risk.
- Once an effective vax exists, denying it is unethical—hence active comparators. WHO policy brief on vaccine-trial ethics (Nov 29 2021): apps.who.int/iris/handle/...
- Why alum vs saline? Gardasil contains alum adjuvant Alum mimics the local redness/soreness a real shot causes, so blinding is preserved Ethical aim: the only difference between groups is HPV antigens Alum has 90 yrs of use; 0.5 mg Al ~ < 10 % daily dietary intake - no credible neuro/autoimmune link
