Everything you need to know about AstraZeneca jab and blood clot fears

THE VACCINE programme in the UK has changed course due to blood clot fears.

Like many other European countries, including Germany and France, the UK will no longer offer younger people the AstraZeneca vaccine.

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Concerns have been raised due to a small number of blood clots that have occurred in patients who have had the AstraZeneca vaccine[/caption]

Medicine regulators today said that those under 30 will be offered vaccines from Pfizer or Moderna instead.

The move came after investigations into a spate of rare blood clotting events, mostly in younger people.

But for the “vast majority” of the population, the benefits of the vaccine, created by Oxford University, still outweigh any risks or side effects.

Meanwhile, in a separate update on its investigations on Wednesday, the European medicines watchdog ruled that unusual blood clots were “very rare side effects” of the jab.

Prime Minister Boris Johnson said in response: “These vaccines are safe, they’ve saved many thousands of lives and people should come forward to get their jabs and we’ll make sure that they get the right jabs.”

Health Secretary Matt Hancock said today’s findings confirm the jab is “safe, effective and the benefits far outweigh the risks for the vast majority of adults”.

Here is everything you need to know:

What blood clots have been found and how many?

The MHRA have been looking at two types of blood clotting events that unusually occur with low blood platelets – called thrombocytopenia:

  • Up until 31 March, there have been 79 cases of rare blood clot events.
  • Of these, 44 were CVST – which prevents the brain from properly draining blood.
  • The remaining 35 were thrombosis in other major veins, such as in the stomach.
  • Sadly, 19 people have died, 11 of whom were under the age of 50.

The cases are out of 20 million doses of the AstraZeneca vaccine, making it extremely rare.

Speaking at a briefing today, Dr June Raine, chief executive of the MHRA, said the odds were four in a million.

She said: “Based on the current evidence, the benefits of the Covid-19 vaccine AstraZeneca against Covid-19 and its associated risks – hospitalisation and death – continues to outweigh the risks for the vast majority of people.

“Our review has reinforced that the risk of this rare suspected side effect remains extremely small.”


Dr June Raine, chief executive of the MHRA, said the odds of a blood clot after the AstraZeneca vaccine were four in a million[/caption]


Experts gave the conclusions of their investigations so far at a press briefing today[/caption]

England’s deputy chief medical officer Professor Jonathan Van-Tam described the blood clots as “vanishingly rare” but “quite serious”.

The same kind of blood clotting cases have been seen in Europe; regulators said today it had investigated a total of 86 rare blood clotting events in Europe, in which 18 people died.

Of these, 62 cases were CVST and 24 were splanchnic vein thrombosis (abdominal).

No rare blood clotting cases with low blood platelets have been reported in those given the Pfizer/BioNTech vaccine. However at least two people have had CVST alone.

Does the AstraZeneca Covid vaccine cause blood clots?

After intense scientific work, the link between the AZ vaccine and blood clots has gotten stronger, but is still not conclusive.

Therefore precautionary measures have been taken while investigations carry on.

Dr Raine said: “The evidence is firming up and our review has concluded that while it’s a strong possibility, more work is needed to establish beyond all doubt that the vaccine has caused these side effects.”


Medicine regulators today said that those under 30 will be offered vaccines from Pfizer or Moderna (pictured) instead[/caption]


Sir Munir Pirmohamed, chairman of the Committee on Human Medicines, said at the MHRA briefing that an immune response to the AstraZeneca vaccine may be behind the blood clots[/caption]

Know the signs

The EMA said people who experience symptoms of clotting within a fortnight of taking the jab should seek immediate medical attention.

They are:

  • shortness of breath
  • chest pain
  • swelling in your leg
  • persistent abdominal (belly) pain
  • neurological symptoms, including severe and persistent headaches or blurred vision
  • tiny blood spots under the skin beyond the site of injection

European regulators were more concrete in their findings.

Speaking at the EMA briefing on Wednesday, Dr Sabine Straus, EMA safety committee chairwoman, said: “Our conclusion is that these clotting disorders are very rare side effects of the vaccine.”

The “unusual” blood clotting should be listed as a “possible side effect of the vaccine”, the EMA’s safety committee decided.

Experts said it was plausible that an immune response to the vaccine could explain the blood clotting events.

Sir Munir Pirmohamed, chairman of the Committee on Human Medicines, said at the MHRA briefing: “The early evidence suggests that this constellation of symptoms is caused by an immune response against platelets which allows the platelets to then lead to clotting in different parts of the body.

The evidence is firming up

Dr June Rainechief executive of the MHRA

“But what we don’t have clearly is the link between the vaccine and how the immune response becomes activated against the platelets.”

Dr Straus said this was similar to a condition suffered by patients treated with a blood-thinning medicine.

The idea had already been floated by scientists who studied cases in Europe, saying the shot may cause the body to activate its own platelets – blood cells which form clots to stop bleeding.

The EMA and the MHRA have previously said there is not an “overall increased risk” in blood clotting conditions, such as deep vein thrombosis.

Who is at risk?

Dr Straus told the Brussels press briefing that “most of the cases [in Europe] occurred in individuals below the age of 60 and in women”.

However, the differences in the type of people being invited to get their vaccine between countries has made it difficult to tease out who is truly at risk.

Therefore, Dr Straus said it could not determine age and gender as risk factors for “very rare” side effects.

The MHRA said in a statement that “the data suggest there is a slightly higher incidence reported in the younger adult age groups”.

But it did not say how many cases occurred in younger people, only that they spanned an age bracket of 18 to 79 years.

Of the 19 deaths in the UK, 11 were under the age of 50, three of whom were under 30.

The MHRA said although most cases were in women (51 of 79), “more women have been vaccinated with Covid-19 Vaccine AstraZeneca than men”.


Dr Straus told the Brussels press briefing that “most of the cases [in Europe] occurred in individuals below the age of 60 and in women”[/caption]

Getty Images – Getty

The MHRA said it would be keeping an eye on the situation and that Brits should still take their jab[/caption]

Should we be worried?

Prof Van-Tam used a nautical analogy to describe the “course correction” in the vaccination programme.

He said it was “quite normal” and “business as usual” for medics to alter their preferences on how to treat patients.

“This is a massive beast that we are driving along at enormous pace with enormous success, this vaccine programme,” he said.

“If you sail a massive liner across the Atlantic then it’s not really reasonable that you aren’t going to have to make at least one course correction during that voyage.”

Knowing that millions of people who have already had their first shot will be wondering if it is safe to get their second one, Prof Van Tam added: “It remains vitally important that people who are called back for their second dose come for it, and all adults in the UK come forward for vaccination when they are offered it.”

One official compared the risk of blood clots after the AZ vaccine to the contraceptive pill – which has been used for decades.

Dr Peter Arlett, head of data analytics at the European Medicines Agency (EMA), told a Brussels briefing: “These are given to women who are normally otherwise healthy, although obviously in a big population some of those women will have other risk factors and other conditions.


“And if we treat 10,000 women with a combined hormonal contraceptive for a year, we will see four excess blood clots in that year.

“So that just gives a benchmark of another medicine given to a healthy population which causes a side effect which occurs rarely but that we need to take into consideration.”

Sir Munir put into context the risk of blood clotting after a vaccine compared with Covid.

He said around 30 per cent of people with Covid suffer low blood platelet counts, while Covid also “causes clotting”.

Some 7.8 per cent of people with Covid suffer blood clots on the lungs, while 11.2 per cent will suffer deep vein thrombosis (DVT), he added.

Dr Michael Head, senior research fellow in Global Health, University of Southampton, said: “It’s important to emphasise that adverse events happen with all medicines, and vaccines are no exceptions.

“Safety surveillance is vital in picking up and assessing signals that emerge from the data.”

Could it just be a coincidence?

Experts have said the cases of blood clotting could just be a coincidence – but the evidence is increasingly strong that it is more than this.

Dr Peter English, immediate past chairman of the British Medical Association’s public health medicine committee, explained that the number of cases is so small that experts say it is very difficult to say with certainty if the vaccines were the cause.

He added that CVST is likely underreported in the general population because it is hard to diagnose.

Therefore, given the recent publicity around CVST and vaccines, doctors may be diagnosing the condition at a higher rate than previously, causing a bias.

There are several risk factors for blood clots in general, including sitting for long periods of time, smoking and drinking alcohol.

They affect people of all ages, and can go unnoticed if the patient doesn’t know the signs. 

Experts have said it could even be that the patients who had blood clotting actually caught Covid-19 before their jab had time to kick in.

Causes of blood clots

There are a variety of things that can cause deep vein thrombosis (DVT) – when you get a blood clot (a sticky mass of blood cells) in a vein that is deep below the skin.

These include:

  • Inactivity- when you are inactive your blood tends to collect in your lower body, your calfs for example. If you are inactive for a substantial length of time your blood can slow down significantly increasing your risk of DVT
  • Hospital- Long surgical procedures to the leg, hips or abdomen, and long recovery time where you are largely inactive
  • Blood vessel damage- Injuries such as broken bones or severe muscle damage can damage blood vessels, narrowing them and making a clot more likely. Vasculitis (inflammation of the blood vessels) can also put you at risk
  • Pregnancy – During pregnancy blood clots more easily to prevent too much blood loss while giving birth. Clots can also appear up to six weeks after giving birth.
  • Contraceptive pill (combined) and Hormone Replacement Therapy- The contraceptive pill and HRT both contain the female hormone oestrogen which can cause blood to clot more easily than normal.
  • Others – You are at a higher risk if you: smoke, are overweight, don’t drink enough or are aged 60 plus (particular if you have a condition that restricts your mobility)

Source: thesun
Everything you need to know about AstraZeneca jab and blood clot fears