Reports of recommendations from agencies in the Region of the Americas regarding some serious events following administration of COVID-19 vaccines
On 19 April 2021, the Chilean Institute of Public Health (ISP), through the National Medicines Agency, published recommendations on use of the AstraZeneca vaccine, following a review of the history presented by the European Medicines Agency (EMA) and other international regulatory authorities. They recommended, as a precautionary measure, that administration of the AstraZeneca vaccine be limited to women over 55 years of age and men 18 years of age and older.
The ISP indicated that, like the EMA, they believe that the benefit/risk balance of this vaccine remains positive, since the vaccine's benefit in preventing transmission and reducing the risk of hospitalization and death due to COVID-10 is greater than the risk of thrombosis with thrombocytopenia. In addition, they indicated that, in the case of Chile, there are no reports, to date, of thrombotic events with thrombocytopenia in the Phase three clinical studies of this vaccine.
In the case of Argentina, the National Commission for Vaccine Safety (Conaseva) also issued recommendations regarding the diagnosis and management of COVID-19 thrombotic syndrome following vaccination, establishing that the definition of suspected cases of thrombotic phenomena and thrombocytopenia occurring between 3 and 28 days after vaccination should consider: (a) arterial or venous thrombosis based on clinical suspicion (intense or persistent headache of sudden onset that does not respond to painkillers, visual disturbances, severe abdominal pain, lower-limb pain or edema, dyspnea, or precordial pain), and imaging, depending on the location of the thrombus (CT angiography, MRI angiograph, Doppler ultrasound, VQ scan, etc.); and (b) thrombocytopenia, with platelet counts of less than 150,000/mm3, with peripheral blood smears that rule out other causes, and with no history of heparin use.
In the same report, Conaseva indicates that there is a concern about COVID-19 vaccination for people with a history of Guillain-Barre Syndrome (GBS), and therefore recommends, on an interim basis, that: (a) people with a history of non-vaccine-related GBS may receive the COVID-19 vaccine; (b) in people with a history of GBS related to vaccines in general, the benefit/risk of administering the COVID-19 vaccine should be evaluated; and (c) in people with a history of GBS after receiving the COVID-19 vaccine, administration of a second dose of the COVID-19 vaccine is contraindicated.