How does the Oxford-AstraZeneca vaccine work?

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AstraZeneca vaccine

What is the latest advice?

The Joint Committee on Vaccination and Immunisation (JCVI) – the government’s advisory body – has now suggested that “adults aged 18-39 years with no underlying health issues be provided an alternative to the Oxford-AstraZeneca vaccine, if available and does not create vaccination delays.”

According to the MHRA, there is a very modest – but slightly higher than usual – incidence of a rare form of clot in younger adult age groups, especially when the risk of infection with coronavirus is extremely low, as it is now.

For persons in their 40s, the chance of developing a clot is around one in 100,000; for those in their 30s, the risk is around one in 60,000.

On the basis of current evidence, the following is recommended:

  • Anyone who develops clotting after receiving the vaccination should avoid receiving a second dose.
  • Individuals with a history of blood problems (who are at risk of clotting) should use AstraZeneca only when the benefits outweigh the dangers.
  • Pregnant women should discuss the advantages and dangers with their physicians.

What’s known about the risk?

The MHRA investigated unusual blood clots in persons who had recently received the Oxford-AstraZeneca vaccination in the United Kingdom.

It discovered 242 cases of clotting and 49 fatalities following the administration of an estimated 28.5 million AstraZeneca vaccination doses across the UK from January to April.

According to the MHRA, around four persons in a million should be expected to acquire this type of blood clot, yet the average incidence is difficult to quantify due to their rarity.

Additionally, the regulator stated that it had not been established that the jab caused the clots.

Dr June Raine, the institute’s director, stated that while the relationship was “firming up,” further proof will be required.

For the great majority of people, the benefits of the AstraZeneca vaccine outweigh the virus’s dangers of hospitalization and death, she added. However, it was more “finely balanced” for younger age groups.

What are these rare blood clots?

The MHRA research examined individuals who experienced clots linked with a low platelet count following vaccination with the Oxford-AstraZeneca vaccine.

Platelets are little blood cells that aid in the formation of clots in order to halt bleeding.

There is a subtype of these clots known as Cerebral Venous Sinus Thrombosis (CSVT).

CVST occurs when a blood clot develops in one of the head’s major veins, preventing blood from draining from the brain.

As a result, blood cells may rupture and enter brain tissue, eventually resulting in a stroke.

Clots can form spontaneously and are more prevalent in younger women, but remain extremely rare.

What symptoms should I watch out for?

According to the MHRA, anyone experiencing these symptoms four days or more after receiving the Oxford-AstraZeneca vaccination should seek immediate medical attention:

  • An excruciating or persistent headache
  • Perplexed vision
  • Pain in the chest
  • Breathlessness
  • Legs swollen
  • Abdominal discomfort that persists
  • Unusual bruising of the skin
  • Points of reference (not including the injection site)

The MHRA emphasizes that covid infection can increase the likelihood of clots.

What have other countries said about the AstraZeneca vaccine?

Clotting should be classified as an extremely unusual vaccination adverse effect, according to the European Medicines Agency (EMA).

Following a review of 86 similar cases in the EU, the EMA found that the vaccine’s benefits outweighed the risks and that there was no conclusive causal relationship.

Nonetheless, Denmark has halted its AstraZeneca rollout entirely – while Germany, Spain, Italy, and Ireland have all postponed vaccinations for those under the age of 60.

France recommends that it be administered solely to individuals aged 55 or older, whereas Australia recommends that individuals under the age of 50 receive the Pfizer vaccine instead.

How does the Oxford-AstraZeneca vaccine work?

It is derived from a weakened strain of the common cold virus (adenovirus) found in chimps. It has been engineered to incorporate genetic information shared by the coronavirus – despite the fact that it is incapable of causing disease.

Once injected, it instructs the body’s immune system on how to combat a genuine virus.

Source : BBC News

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