In a national address, the prime minister invited everyone over the age of 18 who has been double vaccinated for more than three months to book their booster jab.
It marks a change to the previous advice, which stated that people would be eligible for a booster jab six months after their second vaccine.
The news comes after the UK’s Covid-19 alert level was increased from 3 to 4 and 48,854 new positive cases were recorded on Sunday.
In his announcement, Mr Johnson said everyone over the age of 18 will be able to book their booster jab through the NHS website from Wednesday 15 December.
To support this, new vaccination sites will be set up and opening hours at existing sites will be extended.
But what exactly is a booster jab and why might we need them?
What is a booster jab?
A booster jab is an additional dose of a vaccine that was administered before, and gives the immune system a top up to ensure a good level of antibodies are present.
Dr Ashish Srivastava, GP and Medical Director at Gogodoc told the PA news agency: “Vaccines contain a weakened form of the disease-causing virus or bacteria, and work by triggering your immune system to attack the foreign organism, like it would if you actually had the disease.
“As a result, your immune system is able to ‘remember’ the disease-causing bacteria or virus, and if you’re exposed to it again, your body’s defence cells (antibodies) can recognise and kill the germ before it causes harm.
“Boosters are the same vaccine which can be given, weeks, months or even years after the first vaccine in order to boost your immune system with a further weakened form of the virus.”
Who will need a booster?
During the early planning stages of the booster programme, the NHS aimed to administer the jabs to more than 30 million of the most vulnerable people in the UK, including all adults aged 50 and above, and anyone over 16 who qualifies for a flu jab.
However, this guidance has changed due to the omicron variant “spreading much faster than Delta”, according to the UK’s chief medical officer.
The new guidance advises that all adults over the age of 18 who have been double vaccinated for more than three months should get a booster jab.
In his address on Sunday, Mr Johnson said the UK is “facing an emergency battle” against the spread of omicron, which is doubling “every two to three days”.
“No-one should be in any doubt: there is a tidal wave of omicron coming, and I’m afraid it is now clear that two doses of vaccine are simply not enough to give the level of protection we all need,” he said.
How can I book a vaccine booster jab?
If you are eligible for a vaccine booster jab, you can book an appointment through the NHS website here.
If you’ve had a positive Covid test, wait four weeks (28 days) before booking your booster, starting from the date you had the test.
Are booster jabs needed for holidays?
Maybe. It has been reported that booster jabs might be needed for quarantine-free travel abroad in future.
A government source previously told the Mail on Sunday: “The assumption is that you will be required to have the most up-to-date health passport.
“So if the advice is to have a booster six months after your second jab, then that is what you’ll need.”
Currently, Britons who have received both doses of a Covid vaccine are exempt from quarantine when they return from most countries, except for those on the UK government’s “red” list. Those who have not yet been vaccinated must isolate for 10 days when they return.
But at least five countries have set an “expiry date” on vaccination statuses, with varying lengths of time for when tourists are considered immune to Covid-19 after a second jab.
Austria and Croatia were the first to set such a deadline, which was initially 270 days after a second jab but both countries have now extended it to a year. They are joined by Switzerland.
Vietnam will only allow fully-vaccinated travellers to enter the country in a phased approach, but tourists must have had their second dose of the vaccine between 14 days and one year before travel.
Under policies set by Israel’s Health Ministry, vaccine booster jabs are required six months after the second jab of a Covid vaccine. In line with this, the Israeli government has added an expiry date of six months to vaccine passports (Covid Green Pass) currently needed to get into the country’s indoor venues.
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