CoViD vaccines and thrombotic events: EMA issued warning to patients and healthcare professionals

Hamid A. Merchant

Research output: Contribution to journalComment/debatepeer-review

26 Citations (Scopus)


There have been recent reports of haemorrhage, blood clots and thrombocytopenia following administration of CoViD-19 vaccines that have raised concerns over the safety of genetic vaccines for people with pre-existing coagulation disorders or those on certain medications. This had also led to temporary suspension of Oxford/AZ CoViD vaccine in a number of countries across Europe. As a result, Medicine and Healthcare Regulatory Authority, UK (MHRA) and European Medicines Agency (EMA) initiated a rigorous scientific review of pharmacovigilance data and available evidence to assess the potential association of the vaccine to recent thrombotic events. Vaccines are one of the great discoveries in medicine that has improved life expectancy dramatically. Nonetheless, genetic vaccines are new, and their long-term safety evaluation is a key to identify potentially contraindicated group of subjects, for instance, patients with history of blood disorders, past or current thrombocytopenia or pre-existing immunological conditions. The early signs of rare side effects during pharmacovigilance that may lead to severe adverse outcomes should never be dismissed just on the basis of prevalence statistics, but require thorough scientific investigations and clinical correlation to rule out a potential causal link. We, therefore, welcome EMA’s stance on issuing a caution to the public and physicians and support their decision of continued monitoring of thrombotic events more closely with necessary scientific investigations.
Original languageEnglish
Article number32
Number of pages2
JournalJournal of Pharmaceutical Policy and Practice
Issue number1
Publication statusPublished - 24 Mar 2021


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