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The Long and Winding Road
Published in Norman Begg, The Remarkable Story of Vaccines, 2023
Once the first-time-in-human study is over, there may be other small trials to look at what happens with the same vaccine, but containing different amounts of the active ingredient. The idea is to see how volunteers react to different doses, to work out which is the best dose to take forward into larger trials. It’s rather like trying different amounts of spices to make a perfect curry and is called dose ranging. Too low a dose and the vaccine won’t generate antibodies. Too high a dose causes unacceptable side effects. The aim is to find the lowest possible dose that still generates antibodies. Surprisingly, there isn’t necessarily a direct correlation between the dose and the response. In the trial of the Oxford/AstraZeneca COVID-19 vaccine, volunteers who received a half dose for their first injection were better protected than those who got the full dose.
Impact of the COVID-19 pandemic on England’s national prescriptions of oral vitamin K antagonist (VKA) and direct-acting oral anticoagulants (DOACs): an interrupted time series analysis (January 2019–February 2021)
Published in Current Medical Research and Opinion, 2022
Sajidah Alkhameys, Ravina Barrett
There are reports of rare thrombotic incidents as a side effect of the vaccines, particularly the Oxford/AstraZeneca COVID-19 vaccine (Vaxzevria®), which could require the use of anticoagulants such as DOACs [29,30]. The Expert Haematology Panel guidelines from the British Society for Haematology, recommend the use of non-heparin-based therapies (including DOACs) for the treatment of suspected or confirmed COVID-19 vaccine–induced thrombosis [31]. As the reported thromboembolic events were accompanied by thrombocytopenia, DOACs were also recommended for prophylaxis of thrombotic events when thrombocytopenia was present after receiving the COVID-19 vaccine. However, low-molecular-weight heparin (LMWH) is not used when the platelet count is severely reduced (below 30 × 109/L), but in practice this applies to DOACs as well as this being a practical rule of thumb [32].
Acute Uveitis Following AstraZeneca COVID-19 Vaccination
Published in Ocular Immunology and Inflammation, 2023
Sae Kyung Cho, Xia Ni Wu, Chathri Amaratunge
Adenoviral vector vaccines can cause ocular inflammation by inducing an immunological response to components of the chimpanzee or human adenovirus. Our current knowledge of the detailed mechanisms of molecular mimicry is limited. Vaccines may cause autoimmunity induction by targeting the eyes’ self-proteins in predisposed individuals. However, the overall benefits of the Oxford-AstraZeneca COVID-19 vaccine in preventing COVID-19 have been well established.
COVID-19 AdenoviralVector Vaccine and Central Retinal Vein Occlusion
Published in Ocular Immunology and Inflammation, 2022
Davide Romano, Francesco Morescalchi, Vito Romano, Francesco Semeraro
In conclusion, we are conscious that defining a sure causal relationship between the second dose of vaccine Oxford-AstraZeneca COVID-19 vaccine and disease is not feasible, but we suggest to be aware of patients potentially at risk, focusing on their medical and therapy history.