Vaccine associated thrombocytopenic thrombosis from the eyes of general practice - a thread 🧵
#CovidVaccine #AZ
1/16
#CovidVaccine #AZ
1/16
2/16
The JCVI announcement today recommends to offer alternative #CovidVaccine to AZ in healthy adults < 30 years old (i.e. no underlying health conditions): gov.uk/government/pub…
The JCVI announcement today recommends to offer alternative #CovidVaccine to AZ in healthy adults < 30 years old (i.e. no underlying health conditions): gov.uk/government/pub…
3/16
This is following investigation into a blood clotting phenomenon DISTINCT from typical #VTE but clinically similar to heparin-induced thrombocytopenia (HIT) associated with thrombocytopenia and unusual site thrombosis (with a preponderance for CVST) post-AZ vaccination
This is following investigation into a blood clotting phenomenon DISTINCT from typical #VTE but clinically similar to heparin-induced thrombocytopenia (HIT) associated with thrombocytopenia and unusual site thrombosis (with a preponderance for CVST) post-AZ vaccination
4/16
Cases were first characterised in Germany here: researchsquare.com/article/rs-362… (preprint) describing the immunological basis for clotting i.e. PF4 antibodies --> ⬆️⬆️⬆️D-dimer, thrombocytopenia and ⬇️fibrinogen, disproportionately presenting in young patients
Cases were first characterised in Germany here: researchsquare.com/article/rs-362… (preprint) describing the immunological basis for clotting i.e. PF4 antibodies --> ⬆️⬆️⬆️D-dimer, thrombocytopenia and ⬇️fibrinogen, disproportionately presenting in young patients
5/16
Interim / "living" guidance has since been published on the recognition and best management of probable cases:
thieme-connect.com/products/ejour…
b-s-h.org.uk/media/19512/gu…
Interim / "living" guidance has since been published on the recognition and best management of probable cases:
thieme-connect.com/products/ejour…
b-s-h.org.uk/media/19512/gu…
6/16
Although serious, this phenomenon is rare, estimated by the MHRA to be 4/1,000,000 persons vaccinated in the UK
gov.uk/government/new…
Although serious, this phenomenon is rare, estimated by the MHRA to be 4/1,000,000 persons vaccinated in the UK
gov.uk/government/new…
7/16
To provide some context, the risk of a healthy individual developing a blood clot on a 4+ hour flight is estimated to be 1/6000 i.e. approximately 42 x more likely than developing vaccine associated thrombocytopenic thrombosis
who.int/cardiovascular…
To provide some context, the risk of a healthy individual developing a blood clot on a 4+ hour flight is estimated to be 1/6000 i.e. approximately 42 x more likely than developing vaccine associated thrombocytopenic thrombosis
who.int/cardiovascular…
8/16
Further to the biochemical distinction of this syndrome from typical VTE, there is no apparent association of the AZ vaccine with rates of typical VTE as described in this letter:
thelancet.com/journals/lance…
Further to the biochemical distinction of this syndrome from typical VTE, there is no apparent association of the AZ vaccine with rates of typical VTE as described in this letter:
thelancet.com/journals/lance…
9/16
The JCVI suggestion to defer vaccination for healthy <30 year-olds in favour of awaiting a non-AZ option is beautifully summarised in @alex_freeman slides, noting the *current* risk posed by COVID to these individuals is low enough to warrant this: assets.publishing.service.gov.uk/government/upl…
The JCVI suggestion to defer vaccination for healthy <30 year-olds in favour of awaiting a non-AZ option is beautifully summarised in @alex_freeman slides, noting the *current* risk posed by COVID to these individuals is low enough to warrant this: assets.publishing.service.gov.uk/government/upl…
10/16
Context is everything: Note that the risk / benefit changes in the event of another wave of COVID due to exposure risk:
Context is everything: Note that the risk / benefit changes in the event of another wave of COVID due to exposure risk:
11/16
This is the same principle for pausing the new AZ study in children: the risk of hospitalisation & death from COVID in children remains very low, and thus the need for mass vaccination is not as pressing, allowing time for further investigation: covid19vaccinetrial.co.uk
This is the same principle for pausing the new AZ study in children: the risk of hospitalisation & death from COVID in children remains very low, and thus the need for mass vaccination is not as pressing, allowing time for further investigation: covid19vaccinetrial.co.uk
12/16
⬆️Age and/or presence of certain comorbidities is linked with ⬆️risk of hospitalisation due to COVID. It should be borne in mind that hospitalisation with COVID carries a high risk of thrombosis, with an estimated prevalence of 17.4%: pubmed.ncbi.nlm.nih.gov/33043231/
⬆️Age and/or presence of certain comorbidities is linked with ⬆️risk of hospitalisation due to COVID. It should be borne in mind that hospitalisation with COVID carries a high risk of thrombosis, with an estimated prevalence of 17.4%: pubmed.ncbi.nlm.nih.gov/33043231/
13/16
As such, for the majority of patients we are currently vaccinating, the benefits outweigh the risks:
gov.uk/government/new…
As such, for the majority of patients we are currently vaccinating, the benefits outweigh the risks:
gov.uk/government/new…
14/16
Information to provide to patients - red flags to seek urgent medical advice. Note that post-vaccination headache is common (~50%); the emphasis is on those developing 4 or more days post-vaccination +/- symptoms as below
Information to provide to patients - red flags to seek urgent medical advice. Note that post-vaccination headache is common (~50%); the emphasis is on those developing 4 or more days post-vaccination +/- symptoms as below
15/16
Currently, the @MHRAgovuk recommend that anyone in whom a first dose of AZ has been given without incident should continue to come forward for their 2nd dose when they are due.
Currently, the @MHRAgovuk recommend that anyone in whom a first dose of AZ has been given without incident should continue to come forward for their 2nd dose when they are due.
16/16
What I cannot get my head around is the @MHRAgovuk precautionary advice regarding individuals with increased thrombosis risk. Considering the above, this does not appear to be an independent risk factor. Can any experts explain this for me? @bhwords @ProfMakris @karenbr001
What I cannot get my head around is the @MHRAgovuk precautionary advice regarding individuals with increased thrombosis risk. Considering the above, this does not appear to be an independent risk factor. Can any experts explain this for me? @bhwords @ProfMakris @karenbr001
Ask and you shall receive, although it seems unlikely PHE answered this just for me. Either way, a much more measured selection of conditions for exclusion/caution of AZ vaccine here: gov.uk/government/pub…
Still not convinced re: inherited thrombophilia...
Still not convinced re: inherited thrombophilia...
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