How do we know Covid vaccines are safe?

By Michelle Roberts
Health editor, BBC News on-line

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Several European international locations not too long ago paused use of the Oxford-AstraZeneca vaccine after stories {that a} small variety of folks given the shot additionally developed blood clots.

Regulators say there is no evidence that the vaccine is linked to or liable for these occasions.

What occurred?

Some not too long ago immunised folks suffered an especially uncommon type of blood clot – cerebral sinus vein thrombosis (CSVT) – within the mind.

In the UK, 5 circumstances of CSVT – one among them deadly – were recorded among 11 million people who received the vaccine.

The European Medicines Agency (EMA) obtained a further 13 stories of CSVT. It can happen naturally and no hyperlink to the vaccine has been established.

Both the UK regulator and the EMA concluded that the vaccine is secure.

As a precaution, regulators will proceed to watch the state of affairs and advise signs, such as unusual bruising or persistent headache after vaccination, ought to immediate a medical test.

Covid an infection might be severe and in addition make clots extra probably.

How do we know a vaccine is secure?

Safety trials start within the lab, with exams and analysis on cells and animals, earlier than shifting on to human research.

The precept is to begin small and solely transfer to the subsequent stage of testing if there are no excellent security issues.

What function do trials have?

If the protection information from the labs is nice, scientists can test the vaccine or therapy is efficient.

That means exams on massive numbers of volunteers – about 40,000 within the case of Pfizer-BioNTech, the first to be approved in the UK.

Half are given the vaccine and the opposite half a placebo jab. The researchers and members are not advised which group is which, till after the outcomes, to keep away from bias.

media captionBBC’s Laura Foster explains the order during which the Covid vaccine might be given

All of the work and findings are checked and verified independently.

The Covid vaccine trials occurred at breakneck velocity, however they did not skip any steps.

What is the fast-track approval for vaccines in opposition to new variants?

Scientists hope to tweak coronavirus vaccines to make sure they proceed to supply excessive safety as new variants of the illness emerge.

The UK’s drug regulator says new vaccines might be fast-tracked for approval if wanted.

No corners might be lower, with security paramount.

But prolonged scientific trials with 1000’s of volunteers won’t be wanted.

Instead, information from present research and ongoing real-world use might be used.

Will the vaccine give me negative effects?

Vaccines do not provide you with a illness. Instead, they train your physique’s immune system to recognise and struggle the an infection they’ve been designed to guard in opposition to.

Some folks do expertise gentle signs after being vaccinated. This isn’t the illness itself, however the physique’s response to the vaccine.

Common reactions which will have an effect on multiple in 10 folks and sometimes get higher inside days embody chills, tiredness and aching muscle tissues.

Who approves vaccines or therapies?

Approval is barely given within the UK if the regulator is completely satisfied {that a} vaccine is secure and efficient.

Checks proceed after approval to ensure there are no additional negative effects or long-term dangers.

Independent consultants on the Joint Committee on Vaccination and Immunisation resolve how greatest to make use of a vaccine and who ought to get it.

What’s within the Covid vaccines?

Pfizer-BioNTech’s vaccine (and Moderna’s) makes use of bits of genetic code to trigger an immune response. These are known as mRNA vaccines.

They do not alter human cells, however merely current the physique with directions to construct immunity to Covid.

The Oxford-AstraZeneca vaccine makes use of a innocent virus altered to look much more just like the pandemic virus.

Vaccines typically comprise different elements, like aluminium, that make the vaccine secure or more practical.

What about allergy symptoms?

Allergic reactions to vaccines are uncommon. For any permitted vaccine, the elements are listed.

There have been severe however treatable allergic reactions in a really small variety of folks given the Pfizer-BioNTech vaccine.

As a precaution, the MHRA says folks with a historical past of serious allergic reactions to any of the elements on this vaccine shouldn’t presently have this jab.

Be conscious that anti-vaccine tales are unfold on-line by way of social media. These posts are not based mostly on scientific recommendation (or mix info with misinformation).

How the vaccines compare?

What if I’ve already had Covid?

People will nonetheless be provided the jab even when they’ve had Covid-19 up to now.

That’s as a result of pure immunity might not be long-lived and immunisation may provide extra safety.

Guidance says there are no security issues about giving jabs to folks with “long” Covid both. But individuals who are presently unwell with Covid-19 shouldn’t obtain the vaccine till they’ve recovered.

How animal-friendly are vaccines and do they comprise alcohol?

Some vaccines, such because the shingles vaccine and the youngsters’s nasal flu vaccine, can comprise pork gelatine.

The Covid vaccines from Pfizer, Moderna and AstraZeneca do not comprise this, or every other animal merchandise.

The British Islamic Medical Association says there may be negligible alcohol in it – not more than in bread, for instance.

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