How long does it take to build immunity after the Covid vaccine?

History was made this morning as the first approved coronavirus vaccine doses in the world were given out.

Grandma Maggie, 90, was the first recipient of the Pfizer/BioNTech injection, which was approved in the UK last week.

It has been hailed ‘V-Day’ by health secretary Matt Hancock as the NHS launches its biggest mass vaccination programme in history.

But when will Maggie – and the other people to have received a Covid-19 jab today – actually be protected from the deadly disease?

According to experts, the ‘best immunity’ from the Pfizer vaccine comes seven days after the second dose onwards.

People who receive the injection will have two doses three weeks apart.

The best protection comes a week after the second dose is delivered, but there will be some level of protection around 12 days after the first jab.

So that would mean Maggie, and those injected today, should be properly protected in 28 days’ time, provided they get their second jab in exactly three weeks.

Professor Sir Munir Pirmohamed, chair of Commission on Human Medicine expert working group, told a Downing Street press conference last week: ‘From the data that has been presented to us, people will be immune seven days after the second dose.

‘Partial immunity does occur after the first dose. And we can see some protection occurring after day 12 of the first dose, but the best immunity is seven days after the second dose.’

Sir Munir said approval of the vaccine was a ‘historic moment’.

‘We are in the midst of a once-in-a-century pandemic and I think this is a historic moment,’ he added.

‘The UK is now one step closer to providing a safe and effective vaccine to help in the fight against Covid-19, a virus that has affected each and every one of us in some way. This will help to save lives.’

He said regulators had been given ‘unprecedented access’ to the raw data, including clinical trials and manufacturing processes.

‘The data showed that this vaccine is 95% effective,’ he added.

‘It is effective within all the groups who were given the vaccine in the trial irrespective of age, sex, race or country they lived in.’

On the safety of the vaccine, he said: ‘The trials had about 40,000 individuals and half of those received the vaccine and half received the placebo.

‘From the data that has been provided most of the adverse effects were mild and short-lasting. Usually lasted for a day or two – similar to the kind of effects you get after any other vaccine.

‘So that is really important to note that we haven’t identified any serious adverse reactions throughout the trials.’

The UK is set to get 4 million doses of the Pfizer jab by the end of the year – with vaccinated Brits being given cards to prove they’ve had the injection.

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