Thread by @ProfMakris

What is the risk of vaccine-induced immune thrombocytopenia and thrombosis (VITT) after a 2nd AZ vaccine dose? This is the commonest question I get at present on twitter, email and in clinic. 1/6

The information released by the MHRA (the UK regulator) two days ago on their website stated that they have had 15 cases of 2nd dose VITT after 9 million 2nd doses of the AZ vacc administered (ie 1 VITT case every 600,000 2nd doses of the AZ vaccine). tinyurl.com/s53nf2w 2/6

If the rare of VITT in the UK after 2nd doses of the vaccine was the same as after the the 1st dose, we should have had (309-15)x9/23.9= 110.7 cases. According to the MHRA we have had 15 but expected 110. 3/6

However, I have neither seen nor heard of a typical case of VITT after 2nd AZ vaccination. I discuss VITT with haemostasis and thrombosis doctors every day but none of us has seen a typical 2nd AZ dose VITT up to today. 4/6

I am not disputing that the MHRA have had 15 reports but are they true VITT cases? The onus is on the MHRA to publicly explain the clinical features and laboratory results of these 15 cases. People are deciding on whether to have a 2nd dose and deserve the information. 5/6

I have an open mind as to whether we will see any 2nd AZ dose VITT cases, but so far (after 9 million doses) I have not seen any convincing cases. 6/6