‘No biological reason’ to link blood clots to COVID vaccine

Norway, Denmark and Iceland have suspended their rollout of the Oxford University/AstraZeneca COVID vaccine following the death of a 60-year-old woman who developed a blood clot after being vaccinated.
 
But Professor Robert Booy, a vaccine expert at the University of Sydney says there is no cause for concern.
 
‘The issue of blood clots occurring is, first of all, one of coincidence. We expect people to have clots coincidentally with vaccination in the previous day or week,’ he told newsGP.
 
‘There’s no biological reason to think, from the information we already have via millions of people, that the vaccine is causing clots, but we do know that the disease does cause clots.
 
‘So the concern is that the increased risk of clotting seen with COVID-19 is the real factor at hand.’
 
Taken as a precautionary measure, the pause will allow for investigations to be carried out on the quality of the batch, containing one million doses which were delivered to 17 EU countries.
 
This is not the first time concerns over vaccine risks have been raised following deaths in Europe, but Australia’s vaccination program has not been affected.
 
Italy and Austria have also placed a temporary pause on Oxford University/AstraZeneca vaccines taken from a particular batch following three blood clot-related deaths and one illness after the patients received the shot. As of 9 March, two other reports of similar conditions were received for the same batch.
 
But the European Medicines Agency (EMA) claims there is no evidence linking two deaths from blood clots to the vaccine, echoing the reassurance from Professor Booy.
 
The EMA released a statement on a preliminary investigation showing that ‘there is currently no indication that vaccination has caused these conditions, which are not listed as side effects with this vaccine’ and a batch quality defect is at this stage is ‘considered unlikely’.
 
‘The vaccine’s benefits continue to outweigh its risks and the vaccine can continue to be administered while investigation of cases of thromboembolic events is ongoing,’ the EMA said.
 
There is a body of evidence that coronavirus is associated with blood clotting, supporting the EMA’s claim that information available so far indicates that the number of thromboembolic events in vaccinated people is no higher than that seen in the general population.
 
The UK’s Medicines and Healthcare Products Regulatory Agency has also indicated that there is a lack of evidence that the vaccine had caused the issues, recommending people still get vaccinated.
 
Blood clots can occur naturally and are not uncommon, and recent reports of blood clots did not exceed what would have occurred naturally in the vaccinated population, the agency said.
 
So should patients, GPs and other health professionals involved in Australia’s vaccine rollout be concerned? Professor Booy thinks not.
 
‘I think they’ll [GPs] have a watching brief and are likely to be reassured quite quickly,’ he said.
 
‘I imagine that extensive analysis [on blood clot risks] will be done, and its likely to show that the background rate of clotting has not increased with this vaccine.
 
‘But the countries involved in the suspension will make their deliberations based on careful checking of what the background rate of clotting will be by age.’
 
The Australian Government has announced the EU’s suspension on the Oxford University/AstraZeneca vaccine will not impact Australia’s rollout, with the Therapeutic Goods Administration’s advice on the vaccine unchanged.
 
Estonia, Lithuania, Luxembourg and Latvia have also suspended the vaccine, while France and Germany are continuing with their rollout.
 
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AstraZeneca blood clots COVID-19 vaccine vaccine safety