Barts-MS rose-tinted-odometer: ★★
Last week I heard from an Italian colleague that in Italy when many people arrive for the COVID-19 vaccine slot and find out that the vaccine on offer is the Oxford-AstraZenca (AZ) vaccine they say no thank you and leave. The main reason they give for turning down the AZ vaccine is the thrombosis risk. I wonder if these people are aware of the new data that emerged last week (see below).
In this big data study from the US, the incidence of cerebral venous thrombosis (CVT) after COVID-19 diagnosis was 39.0 cases per million people who get COVID-19. This was higher than the CVT incidence after influenza (0.0 per million people or adjusted relative risk = 6.7) or after receiving the Pfizer-BionTech or Moderna RNA vaccines (4.1 per million people, adjusted relative risk = 6.4 higher).
The bottom line is COVID-19 is way riskier than the COVID-vaccines in causing thrombus and contrary to a common belief the risk is not only restricted to the AZ or J&J vaccines, which use adenoviral vectors but with the COVID-19 mRNA vaccines well. This suggests it may be the immune response to the SARS-CoV-2 spike protein that induces cross-reactivity and sets up a very rare thrombotic state.
It is never easy to explain risks and relative risks, but the following infographic doing the rounds on social media may help. What do you think?
Please #StayCalm and #GetVaccinatedASAP.
Taquet et al. Cerebral venous thrombosis: a retrospective cohort study of 513,284 confirmed COVID-19 cases and a comparison with 489,871 people receiving a COVID-19 mRNA vaccine. OSF 15-April-2021.
Using an electronic health records network we estimated the absolute incidence of cerebral venous thrombosis (CVT) in the two weeks following COVID-19 diagnosis (N=513,284), or influenza (N=172,742), or receipt of the BNT162b2 or mRNA-1273 COVID-19 vaccines (N=489,871). The incidence of portal vein thrombosis (PVT) was also assessed in these groups, as well as the baseline CVT incidence over a two-week period. The incidence of CVT after COVID-19 diagnosis was 39.0 per million people (95% CI, 25.2–60.2). This was higher than the CVT incidence after influenza (0.0 per million people, 95% CI 0.0–22.2, adjusted RR=6.73, P=.003) or after receiving BNT162b2 or mRNA1273 vaccine (4.1 per million people, 95% CI 1.1–14.9, adjusted RR=6.36, P<.001). The relative risks were similar if a broader definition of CVT was used. For PVT, the incidence was 436.4 per million people (382.9-497.4) after COVID-19, 98.4 (61.4-157.6) after influenza, and 44.9 (29.7-68.0) after BNT162b2 or mRNA-1273. The incidence of CVT following COVID-19 was higher than the incidence observed across the entire health records network (0.41 per million people over any 2-week period). Laboratory test results, available in a subset of the COVID-19 patients, provide preliminary evidence suggestive of raised D-dimer, lowered fibrinogen, and an increased rate of thrombocytopenia in the CVT and PVT groups. Mortality was 20% and 18.8% respectively. These data show that the incidence of CVT is significantly increased after COVID-19, and greater than that observed with BNT162b2 and mRNA-1273 COVID-19 vaccines. The risk of CVT following COVID-19 is also higher than the latest estimate from the European Medicines Agency for the incidence associated with ChAdOx1 nCoV-19 vaccine (5.0 per million people, 95% CI 4.3–5.8). Although requiring replication and corroboration, the present data highlight the risk of serious thrombotic events in COVID-19, and can help contextualize the risks and benefits of vaccination in this regard
General Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not necessarily reflect the positions of the Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust.