(Alliance News) - The World Health Organization's vaccine advisors called Thursday for more data on the incidence of blood clots in people who received the AstraZeneca PLC Covid-19 vaccine outside Europe.
The WHO's strategic advisory group of experts on Immunisation updated their guidance on the use of AstraZeneca's coronavirus jab, rewriting the section on precautions in light of data from Europe on clotting.
"WHO continues to support the conclusion that the benefits of these vaccines outweigh the risks," the UN agency stressed in a statement.
On April 7, strategic advisory group of experts said a link between AstraZeneca's Covid-19 jabs and blood clots was plausible but unconfirmed, underlining that reported occurrences were "very rare".
In light of evidence emerging from ongoing vaccination programmes, they have updated their recommendations on the AstraZeneca jab, which is being deployed in 157 territories according to an AFP count.
Strategic advisory group of experts said most clotting cases were reported in Britain and the EU, with very few cases noted in other countries.
They said it was unknown whether there was a risk of clotting from the second dose of the vaccine, while recommending that those who suffered blood clots after their first injection should not be given the second dose of the two-shot vaccine.
"A very rare syndrome of blood clotting combined with low platelet counts, described as thrombosis with thrombocytopenia syndrome, has been reported around four to 20 days following vaccination," the new guidance says.
"A causal relationship between the vaccine and thrombocytopenia syndrome is considered plausible although the biological mechanism for this syndrome is still being investigated.
"Most of these cases were reported from the UK and the EU. There is considerable geographic variation with regards to the reported incidence, with very few cases reported from non-European countries, despite extensive use of the vaccine.
"An estimation of the risk outside Europe needs further data collection and analysis."
The vaccine currently forms the backbone of the Covax scheme, which ensures that poorer countries can access doses, with donors covering the cost.
Covax has so far shipped more than 40.5 million Covid-19 vaccine doses to 118 participating territories.
The strategic advisory group of experts guidance said that data from Britain, dated March 31, suggested the risk of thrombocytopenia syndrome was approximately one case per 250,000 vaccinated adults, while the rate in the EU was estimated at one in 100,000.
It said current data from Europe suggested that the risk might be higher in younger adults compared with older adults.
"No specific risk factors have yet been identified," it said.
By Robin Millard
source: AFP
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