Abstract
Background: The COVID-19 vaccine from AstraZeneca (AZD1222) is one of several vaccines introduced to provide immunity against SARS-CoV-2. Recently, more than 50 cases have been reported presenting a combination of thrombosis, thrombocytopenia, and remarkably high levels of anti-platelet factor 4 (PF4)/polyanion antibodies post-AZD1222 vaccination. Now linked to the vaccine, the condition is referred to as vaccine-induced immune thrombotic thrombocytopenia. The European Medicines Agency still recommends vaccination with AZD1222, but several European countries have temporally paused and/or restricted its use because of the perceived risk of this severe side effect. Because there is no description of PF4/polyanion antibody testing in the clinical trials, knowledge about the prevalence of such antibodies in a vaccinated cohort is needed.
Objectives: To investigate prevalence of thrombocytopenia and anti-PF4/polyanion antibodies in a population recently vaccinated with AZD1222.
Patients/methods: Four hundred and ninety-two health care workers recently vaccinated with the first dose of AZD1222 were recruited from two hospitals in Norway. Study individuals were screened for thrombocytopenia and the presence of anti-PF4/polyanion antibodies with a PF4/PVS immunoassay. Side effects after vaccination were registered.
Results: The majority of study participants had normal platelet counts and negative immunoassay. Anti-PF4/polyanion antibodies without platelet activating properties were only detected in six individuals (optical density ≥0.4, range 0.58-1.16), all with normal platelet counts. No subjects had severe thrombocytopenia.
Conclusions: We found low prevalence of both thrombocytopenia and antibodies to PF4/polyanion-complexes among Norwegian health care workers after vaccination with AZD1222.
Keywords: COVID-19 vaccines; COVID-19 vaccines/adverse effects; drug related side effects and adverse reactions; platelet factor 4; thrombocytopenia.
【저자키워드】 COVID-19 vaccines, thrombocytopenia, platelet factor 4, COVID-19 vaccines/adverse effects, drug related side effects and adverse reactions, 【초록키워드】 COVID-19, SARS-CoV-2, Vaccine, Antibody testing, COVID-19 vaccine, vaccination, Health care, thrombosis, Immunity, antibody, knowledge, hospital, clinical trials, immune, European Medicines Agency, adverse effects, Adverse reactions, Prevalence, immunoassay, Cohort, COVID-19 vaccines, AZD1222, Platelet, Health care worker, optical, thrombocytopenia, Norway, platelet factor 4, AstraZeneca, Combination, Perceived risk, referred to, optical density, Side effect, Thrombotic thrombocytopenia, subject, first dose, individual, Study participants, thrombotic, Registered, side, Effect, European country, recruited, reported, screened, majority, introduced, the vaccine, presenting, activating, study participant, 【제목키워드】 antibody, Prevalence, COVID-19 vaccination, Health care worker, identify,