Research shows AstraZeneca’s second dose doesn’t raise risk of rare blood clot

UK – A study has shown AstraZeneca’s COVID-19 shot did not increase the instances of rare blood clots with low platelets in people after the second dose.

Data published in the Lancet medical journal found that the estimated rate of thrombosis with thrombocytopenia syndrome (TTS) after the second dose of the vaccine was 2.3 per million in those inoculated, comparable to the typical rate seen in those who have not been vaccinated.

This research, led and funded by AstraZeneca, evaluated reported cases occurring within 14 days of administration of the first or second dose as of April 30, using the Anglo-Swedish drugmaker’s global safety database.

The EU drug 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 shot. It has, however, maintained that overall benefits of both the vaccines outweigh any risks posed by them.

In more related news, Russia’s health officials have given a go-ahead to testing a combination of the AstraZeneca coronavirus shot and the single-dose version of its domestically developed Sputnik V vaccine.

The small study, which was scheduled to start July 26 and end in March next year, will enroll 150 volunteers and look at the mixed regimen’s safety and capability to trigger immune response, records show. It will be conducted in five medical facilities in Moscow and St. Petersburg.

Both shots use a similar technology, employing a harmless virus to deliver genetic material from the spike protein of COVID-19 into the body, which then prompts an immune response.

Russian officials introduced Sputnik V last year as a two-shot vaccine using different viruses in each dose, but they also have separately marketed the first shot as a single-dose alternative dubbed Sputnik Light.

The developers of Sputnik V proposed combining the shots to AstraZeneca in November, suggesting it could increase the effectiveness of the British vaccine. AstraZeneca announced a study to test the combination in December.

In May, however, the ethical committee of Russia’s Health Ministry suspended the process of giving the trial a green light and requested additional documents for review.

Russia gave Spuntik V regulatory approval in August 2020. The vaccine initially faced skepticism at home and abroad because it had only been tested on a few dozen people at the time.

A report in the British medical journal The Lancet this year blunted the criticism, saying large-scale testing showed the vaccine to be safe and having a 91% efficacy rate.

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