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Explainer: What we know so far about the Oxford/AstraZeneca vaccine pause in Ireland

The pause followed an alert from Norwegian authorities about four serious blood clotting cases.

Image: PA

HEALTH AUTHORITIES in a number of countries – now including Ireland – have temporarily paused the use of the Oxford/AstraZeneca vaccine.

The move follows reports of a small number of serious blood clotting events in adults after they had received this vaccine.

A definitive link between the blood clotting events and the vaccine has not been established, but Irish authorities have decided to suspend the use of the jab until a review has been completed by the European regulator.

Here’s what we know so far.

What type of vaccine is this one?

The Oxford/AstraZeneca jab is a viral vector vaccine.

It uses a harmless, weakened version of a common virus which causes a cold in chimpanzees. The virus has been genetically modified so it is impossible for it to grow in humans – people who get the vaccine will not become ill with a chimpanzee cold.

The modified ‘vector’ virus enters a cell in your body and teaches the cell how to produce the Covid-19 spike protein. Your immune system is then ready to fight off the coronavirus if it ever comes in contact with it.

This is a two-dose vaccine that can be stored at normal fridge temperatures. Ireland received the first deliveries of the Oxford/Astrazeneca vaccine in early February.

When did the current issue first emerge?

Earlier last week it was reported that one person in Austria was diagnosed with blood clots and died ten days after vaccination. 

Another person in Austria was admitted to hospital with pulmonary embolism (blockage in arteries in the lungs) after being vaccinated, while one death involving a blood clot was reported in Denmark.

A 50-year-old man is also believed to have died in Italy from deep vein thrombosis (DVT) after being given the Oxford/AstraZeneca jab, while there has been an unconfirmed report of another death in Italy.

Italy and Austria both suspended the use of shots from specific batches of the vaccine last week.

Regulators have stressed that with each of these incidents, there is currently no indication that the vaccine caused the condition.

On Friday, Ireland’s National Immunisation Advisory Committee (NIAC) said no change was warranted in relation to recommendations on the use of this vaccine. This was based on guidance from the World Health Organization (WHO) that there was no reason to stop using it. 

The WHO’s vaccine advisory committee was examining the safety data coming in, and said that no causal link had been established between the vaccine and clotting. 

The European Medicines Agency also said there had been 30 cases of so-called thromboembolic events among five million people who had received the jab in Europe. 

European countries could still keep using the vaccine, the EU’s drug regulator said on Thursday last. 

What happened over the weekend?

On Saturday, Ireland’s medicines regulator, the Health Products Regulatory Authority (HPRA), received a new safety alert from the Norwegian Medicines Agency.

This followed four new and serious rare blood clotting events, including some complicated by very low levels of platelets in the blood of younger adults after vaccination. 

Reuters reported three health workers were among these cases.

Chair of NIAC, Professor Karina Butler told RTÉ’s Brendan O’Connor yesterday that this new alert changed the state of play.

She said these events were “not the sort of usual clots in the legs, but actually clots involving the brain or vessels that wouldn’t normally be involved – and in younger people”. 

“So looking overall it was a number of these small but very are, serious events in people that you might not otherwise expect it in. That raised a safety signal.”

She said the question now is whether these are “totally coincidental random events” that happened to have occurred around the same time because the vaccine is being rolled out to lots of people, or whether there is a causal relationship with the vaccine that may have triggered clots.

Following notification from the HPRA of this new safety alert, NIAC recommended the administration of the vaccine be deferred pending the outcome of an investigation at an EU level. 

The World Health Organization and the European Medicines Agency have both said there is no evidence to support the use of the jab being suspended.

The EMA’s  Pharmacovigilance Risk Assessment Committee (PRAC), is reviewing all cases of thromboembolic events, and other conditions related to blood clots, reported post-vaccination with COVID-19 Vaccine AstraZeneca.

Which countries have suspended it?

Denmark, Norway, Iceland and the Netherlands have also paused their rollout of the jab. Thailand and Bulgaria have delayed the beginning of their roll-outs of the vaccine.

What have the developers said?

The director of the Oxford Vaccine Group today said there is no link between the jab it developed with AstraZeneca and blood clotting.

Andrew Pollard said there was “very reassuring evidence that there is no increase in a blood clot phenomenon here in the UK, where most of the doses in Europe been given so far”.

“It’s absolutely critical that we don’t have a problem of not vaccinating people and have the balance of a huge risk, a known risk of Covid, against what appears so far from the data that we’ve got from the regulators — no signal of a problem,” he told BBC radio.

Yesterday AstraZeneca said among 17 million doses analysed, there was no evidence of increased blood clots from the jab.

The pharmaceutical company said the 15 incidences of deep vein thrombosis (DVT) and 22 events of pulmonary embolism reported among those given the vaccine was “much lower than would be expected to occur naturally in a general population”.

“The nature of the pandemic has led to increased attention in individual cases and we are going beyond the standard practices for safety monitoring of licensed medicines in reporting vaccine events, to ensure public safety,” chief medical officer Ann Taylor said.

“In terms of quality, there are also no confirmed issues related to any batch of our vaccine used across Europe, or the rest of the world.”

How worried should we be about this?

Concern about potential serious side effects are to be expected following news of developments over recent days.

Health officials have been trying to reassure people, stressing that a definitive link has not been established and that this is a precautionary measure.

The HPRA has said it has received a small number of reports associated with blood clots following vaccination with the AstraZeneca vaccine. However, it has not received any reports of the nature of those described by the Norwegian Medicines Agency.

“There is currently no indication that vaccination was the cause of these events, and there may be alternative explanations for their occurrence that are unrelated to the vaccine,” the agency said yesterday.

“However, the safety of the public is of the utmost importance, and it is essential that reports of potential safety concerns, even if very rare, are rigorously and swiftly investigated so that the public can be reassured and if required, appropriate action can be taken.”

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NIAC’s Professor Karina Butler said this precautionary a pause should give people more confidence in the vaccination programme, because it shows how cautious health authorities are being.

“What you want is you want us to deliver safe programmes, we are taking every measure to make sure that that is what we’re doing,” she said.

“So in fact, confidence would be lost if it was felt that there were safety signals that we were ignoring.”

Dr Ray Walley, GP and member of the National Covid-19 GP Liaison Committee told TheJournal.ie that he believes this move shows NIAC is an independent organisation that is willing to “make tough decisions” when data comes through that requires analysis.

“Personally I think it shows it is a healthy, proactive organisation, ignoring nothing and understanding that all populations have a heightened interest in health. It also shows there is a robust programme with adult decisions being made.

They could have waited for the report [from the EMA] at the end of the week, but in the meantime you’d have different media outlets reporting these negative stories, with no answers. To me this is evidence that we are professionally and appropriately reviewing all this and listening to people. When they say ‘are you sure?’, we’re making sure.

Dr Walley said there is a long list of potential causes of thromboembolic disease, including long haul flights, operations around the pelvic area and a genetic pre-disposition:

He also pointed out that the UK, which has a large pool of data now on the AstraZeneca vaccine, has not reported any link between blood clots and the jab.

“The UK has vaccinated 11 million people. I was an NHS GP many years ago for seven years and the UK healthcare system in relation to reporting reactions is a very robust system.”

He said he would be surprised if the pause is not lifted by next week. 

Who’s missing out on vaccines this week because of the pause?

Around 30,000 fewer doses of Oxford/AstraZeneca Covid-19 vaccines will be administered this week due to the pause. This means just 50,000 jabs will be given this week – made up of doses from Pfizer and Moderna only.

The Oxford/AstraZeneca vaccine has been used for the immunisation of frontline healthcare workers since the first delivery in February. Health staff who had a vaccination planned for this week will now see it delayed.

It was also used last week for at least 3,000 people (according to figures up to 12 March) who are in Cohort 4 – those considered at very high risk of severe Covid-19. Up to 20,000 people in this cohort were expected to receive their first dose of the AztraZeneca vaccine this week. These appointments will be delayed.

Health Minister Stephen Donnelly told RTÉ’s Morning Ireland today that he hopes the 30,000 people impacted this week will have their vaccinations rescheduled quickly. However he acknowledged that there may be “a bit of spill over into April”. 

“We should be able to reschedule then and in so doing not have to delay other people,” he said.

“So in other words, do the 30,000 at the same time as people who we were planning on doing in the coming weeks as well.”

If I had a first dose of the AstraZeneca vaccine, what does it mean for me?

Deputy Chief Medical Officer Ronan Glynn has said anyone who feels unwell more than three days after their vaccination or anyone who notices blue spots on their skin should contact a doctor immediately.

You don’t need to take any action if you are feeling well and have not noticed any blue spots on your skin.

Officials are expecting the situation to be clarified by next week and with the 12-week schedule of the AstraZeneca vaccine, this should not result in a delay to second doses, if adequate supplies are delivered. 

- With reporting from AFP and PA.

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