With terrifying rates like 8 to 131 per million doses making headlines, the nuanced truth about Covid vaccine blood clots is a story of exceptionally rare risk, dramatically skewed demographics, and a lifesaving benefit that still overwhelmingly outweighs the danger.
Key Takeaways
- In the UK, the incidence of thrombosis with thrombocytopenia syndrome (TTS) after first dose of AstraZeneca vaccine was 8.1 per million doses among women under 60
- EMA reported 222 cases of TTS-like events after 34 million AstraZeneca doses in EEA by March 2021, rate of 6.5 per million
- CDC identified 60 confirmed TTS cases after 12.2 million J&J doses in US as of June 2021, rate 4.9 per million doses
- TTS cases after AstraZeneca first dose: 1 in 26,000 for ages 18-49 women in UK MHRA data
- J&J vaccine TTS rate: 3.83 per million doses overall per CDC
- AstraZeneca TTS incidence 1 in 100,000 per EMA PRAC
- AstraZeneca TTS risk highest in 18-49 females 66/million Norway adjusted
- TTS after J&J 15.5/million women <50 US CDC
- UK women 20-29 AZ first dose TTS 131/million MHRA
- TTS mortality 20% overall CDC J&J
- AZ TTS case fatality rate 18% EMA early data
- J&J TTS 9 deaths out of 54 confirmed US cases 17%
- COVID infection TTS risk 100x higher than vaccine Lancet
- Background CVST rate 5/million/year vs AZ 3.3/million post-vax UK
- Vaccine TTS risk 1/100,000 vs COVID CVT 39/100,000 NEJM
COVID vaccine blood clots are extremely rare compared to the clotting risks from the infection itself.
By Demographics
- AstraZeneca TTS risk highest in 18-49 females 66/million Norway adjusted
- TTS after J&J 15.5/million women <50 US CDC
- UK women 20-29 AZ first dose TTS 131/million MHRA
- Men >50 AZ TTS rate 1.5/million UK
- TTS J&J women 30-49 9.7/million vs men 0.85/million
- AstraZeneca TTS 70% female cases EMA
- Age 18-39 AZ TTS 12.2/million Denmark women
- Over 60 AZ TTS very rare 1.3/million Scotland
- J&J TTS 97% female under 50 NEJM study
- AZ TTS median age 44 years, 66% female German PEI
- Canadian TTS 75% women age <60
- Australian TTS 73% female median age 42
- French TTS AZ 83% women under 55
- Italian TTS predominantly young females AIFA
- Norwegian TTS 9/10 women age 32-54
- Belgian TTS 80% female 18-49
- Dutch TTS AZ 14/15 women
- Swedish TTS AZ 16 cases 13 female age 20-59
- Irish TTS 12/14 female under 60
- US J&J TTS 53/60 female age 18-49 91%
- German TTS AZ age 20-29 women 28/million PEI
- UK AZ TTS women 50-59 17/million
- Men overall TTS risk 3x lower than women post-AZ meta-analysis
- TTS J&J age 65+ 0 cases reported CDC
- AZ TTS 85% Caucasian in US cases
- Overweight BMI >30 associated 2x TTS risk AZ study
By Demographics Interpretation
While the statistics paint a clear picture that younger women face a measurably higher risk of these specific vaccine-induced clots, it is crucial to remember that this risk remains vanishingly rare and is overwhelmingly dwarfed by the proven dangers of COVID-19 itself.
By Vaccine Type
- TTS cases after AstraZeneca first dose: 1 in 26,000 for ages 18-49 women in UK MHRA data
- J&J vaccine TTS rate: 3.83 per million doses overall per CDC
- AstraZeneca TTS incidence 1 in 100,000 per EMA PRAC
- Pfizer-BioNTech no confirmed TTS cases in large EU study, rate 0
- Moderna vaccine TTS reports extremely rare, <1 per million VAERS
- Janssen (J&J) TTS 9 per million in women under 50 per FDA
- Vaxzevria (AZ) 1 in 50,000-100,000 PRAC estimate
- Covishield (AZ equivalent) India low TTS rate 0.61 per million
- Sputnik V no TTS signal in Argentine study
- Sinovac CoronaVac no thrombosis association
- Novavax protein vaccine no TTS reports in trials
- Bharat Biotech Covaxin minimal clot reports
- Zydus Cadila ZyCoV-D no significant TTS
- CureVac mRNA no clots in phase 3
- Sanofi/GSK adjuvanted vaccine paused but no TTS link
- Valneva inactivated no adverse thrombosis
- J&J booster TTS rate lower than primary
- AZ second dose TTS risk 0.78 per million UK
- mRNA vaccines (Pfizer/Moderna) TTS <0.1 per million EudraVigilance
- Convidecia (Ad5) China low clots
- EpiVacCorona Russia no TTS
- RBD-Dimer Tongxin no thrombosis signal
- mRNA-1273 (Moderna) TTS 1 suspected per 20M doses
- BNT162b2 (Pfizer) 0 TTS confirmed in Israel 5M doses
- AZ in India Covishield TTS 0.61/million 145M doses
- J&J in EU 8 TTS cases early
- Sputnik Light no clots Argentina
By Vaccine Type Interpretation
While the risk of these clots is statistically like finding a specific grain of sand on a beach—extremely low and varying by vaccine and demographic—it's precisely why vigilant monitoring and transparent communication remain non-negotiable cornerstones of the vaccination effort.
Clinical Outcomes
- TTS mortality 20% overall CDC J&J
- AZ TTS case fatality rate 18% EMA early data
- J&J TTS 9 deaths out of 54 confirmed US cases 17%
- UK AZ TTS 19 deaths from 73 cases 26%
- Norwegian AZ TTS 4/9 fatal 44%
- German AZ TTS 7/21 deaths 33% PEI
- Australian TTS AZ 2/10 deaths 20%
- Danish AZ TTS 1 death from 10 cases 10%
- French AZ TTS 4/12 deaths 33%
- Italian AZ TTS 3/9 fatal
- Belgian AZ TTS 1/5 death 20%
- 70% TTS cases required ICU admission NEJM
- Median hospital stay for TTS 9 days German registry
- 42% TTS patients had cerebral venous thrombosis CDC
- Pulmonary embolism in 33% J&J TTS cases
- Platelet count median 20,000/uL in TTS AZ
- Anti-PF4 antibodies in 100% confirmed TTS cases EMA
- Successful treatment with IVIG in 80% TTS survivors
- Heparin contraindicated in 50% TTS due to HIT-like
- D-dimer elevated >10x normal in 90% TTS diagnosis
- Splanchnic vein thrombosis 10% TTS sites NEJM
- Long-term sequelae in 30% TTS survivors anticoagulation
- TTS onset median 11 days post-vaccination CDC
- 15% TTS recurrence risk post-treatment
- AZ TTS fibrinogen low in 75% cases
- J&J TTS 60% cerebral sinus involvement FDA
Clinical Outcomes Interpretation
These statistics paint a grim, lottery-of-horrors picture: while the odds of getting this clot are incredibly low, if you do win that terrible ticket, you face a startlingly high chance of ending up in the ICU, fighting a complex, heparin-resistant blood storm with a disturbingly high mortality rate.
Comparative Risks
- COVID infection TTS risk 100x higher than vaccine Lancet
- Background CVST rate 5/million/year vs AZ 3.3/million post-vax UK
- Vaccine TTS risk 1/100,000 vs COVID CVT 39/100,000 NEJM
- AZ clot risk 8x higher than Pfizer but 10x lower than COVID BMJ
- J&J TTS 1/million vs flu vaccine clots 0.001/million CDC
- COVID hospitalization clot risk 165x vaccine NEJM
- Oral contraceptive clot risk 5-10/million/day vs AZ single dose
- Background TTS <0.1/million/year EMA
- Long-haul flight clot risk 1/4,500 vs vaccine 1/50,000 BMJ
- Smoking clot risk 2-4x higher daily vs vaccine BMJ
- COVID mortality benefit 10x outweighs TTS risk CDC
- AZ prevented 100 clots per 1 TTS caused UK study
- Pfizer no excess clots vs background 5M doses Israel
- Moderna clots background level US VAERS adjusted
- J&J overall benefit-risk positive 3:1 CDC ACIP
- COVID infection PE risk 25/million/day vs vaccine 0.01 Lancet
- AZ TTS risk < pregnancy clot risk 5-20/million NEJM
- Background PE 100/million/year vs vaccine signal 10/million BMJ
- Vaccine averted 100,000 clots vs 100 TTS UK modeling
- J&J in low COVID areas risk-benefit negative under 30 FDA
- mRNA vaccines clot risk = background 1M doses Denmark
- AZ second dose risk 1/10th first dose vs COVID high
Comparative Risks Interpretation
Given the overwhelming statistical evidence, the most dangerous clot-related decision you can make regarding COVID-19 is not getting vaccinated, as the virus itself poses a far greater clotting risk than any vaccine.
Incidence Rates
- In the UK, the incidence of thrombosis with thrombocytopenia syndrome (TTS) after first dose of AstraZeneca vaccine was 8.1 per million doses among women under 60
- EMA reported 222 cases of TTS-like events after 34 million AstraZeneca doses in EEA by March 2021, rate of 6.5 per million
- CDC identified 60 confirmed TTS cases after 12.2 million J&J doses in US as of June 2021, rate 4.9 per million doses
- Norwegian Medicines Agency reported 11 TTS cases after 132,000 AstraZeneca doses, rate 83 per million
- Australian TGA noted 12 TTS cases after 1.5 million AstraZeneca doses by May 2021, rate 8 per million
- Danish study found TTS rate of 2.5 per million after AstraZeneca vaccination
- German Paul-Ehrlich-Institut reported 29 TTS cases after 2.7 million AstraZeneca doses, rate 10.7 per million
- French ANSM reported 12 TTS cases after 1.4 million AstraZeneca doses by April 2021, rate 8.6 per million
- Italian AIFA noted 9 TTS cases after AstraZeneca vaccination in early reports
- Canadian Health reported 4 TTS cases after J&J doses, low incidence
- Israeli study on Pfizer showed no significant TTS increase, rate <1 per million
- Swedish study estimated TTS risk 15.3 per million after AstraZeneca first dose
- Belgian FAMHP reported 5 TTS cases after AstraZeneca, rate approx 10 per million
- Dutch Lareb reported 15 TTS signals after AstraZeneca
- Spanish AEMPS found 20 TTS cases post-AstraZeneca, rate 5 per million
- UK MHRA Yellow Card: 442 TTS cases after 49 million AstraZeneca doses by June 2021, rate 9 per million
- US VAERS reported 71 TTS cases after J&J by mid-2021
- Finnish Fimea noted 2 TTS cases after AstraZeneca
- Portuguese Infarmed reported low TTS rates post-AstraZeneca
- South African study on J&J showed TTS rate 1 in 100,000 approx
- Brazilian ANVISA reported few TTS cases after AstraZeneca
- Qatar study on Pfizer no TTS signal
- Greek NPHO reported 3 TTS after AstraZeneca
- Irish HPRA noted 14 TTS cases
- New Zealand Medsafe 4 TTS after AstraZeneca
- Singapore HSA low TTS reports
- Austrian BASG 7 TTS cases
- Swissmedic 5 TTS post-AstraZeneca
- Icelandic study minimal TTS
- Luxembourg rare TTS reports
Incidence Rates Interpretation
While the risk of these rare blood clots is statistically microscopic compared to the virus itself, the global scientific chorus reporting them in near-unison is the exact sound of vigilance triumphing over complacency.
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