A new study has confirmed that the AstraZeneca COVID-19 vaccine carries a small risk of rare blood clots with low platelets after the first dose.
According to the study led and funded by AstraZeneca, the vaccine, however, has no extra risk of blood clots after the second dose.
As reported by Reuters, the study already published in The Lancet medical journal found that that the estimated rate of Thrombosis with Thrombocytopenia Syndrome after the first dose was 8.1 per million in those inoculated.
However, after the second dose of the COVID-19 vaccine, branded Vaxzevria and invented by Oxford University, the rate was 2.3 per million, comparable to that seen in unvaccinated people, AstraZeneca stated.
Recall that the AstraZeneca COVID-19 vaccine has faced several setbacks, including production delays, and rare cases of severe side-effects, including TTS, which led to several countries restricting or stopping its use, as well as calls for more investigation by regulators around the world.
The European Union’s drugs regulator has been looking into cases of TTS since March and has found a possible link to Vaxzevria, and to Johnson & Johnson’s single-dose COVID-19 shot. It has, however, maintained that the overall benefits of both vaccines outweigh any risks posed by them.
According to Reuters, findings evaluated cases reported as of April 30 that occurred within 14 days of receiving the first or second dose, using AstraZeneca’s global safety database.
The study authors, however, stated that the limitations of the analysis included reliance on data provided by healthcare providers and those who got vaccinated, which might lead to the under-reporting of cases.
The report added that “heightened media attention might have led to event misclassification.”
As of the cut-off date, 13 cases of TTS had been identified globally after the second dose in people aged 45 years to 85 years, including eight women. Some 399 cases were reported after the first, the study showed, while data used for the number of doses administered was limited to the EU, European Economic Area, and Britain.
“Unless TTS was identified after the first dose, these results support the administration of the two-dose schedule of Vaxzevria, as indicated, to help provide protection against COVID-19 including against rising variants of concern,” AstraZeneca senior executive Mene Pangalos said in a statement.
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