LONDON—No new cases of rare and severe blood clots following vaccination with AstraZeneca’s COVID shot have been reported in Britain in recent weeks after a decision to restrict its use in under-40s, British scientists said on Wednesday. Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a combination of blood clots and low platelet levels which has been labelled as a rare side effect of the viral vector COVID vaccines made by AstraZeneca and Johnson & Johnson. A higher occurrence of the side-effect in younger people has led to many countries to put age restrictions on AstraZeneca’s shot. Around 85% of those who suffered rare blood clots after vaccination with AstraZeneca’s COVID-19 shot in Britain were under 60 even though more of the shots were given to the elderly, the study found, in one of the fullest characterizations of the syndrome so far. It found that in those aged under 50, incidence …