The comments come as many European countries are seeing an increase in coronavirus cases and preparing to step up Covid restrictions.
At a glance: 5 key points
- PM said there was a wave of infection across Eastern Europe
- Johnson stressed the need to get booster jabs
- Spoke of his concerns about the Delta variant
- Covid deaths rose 10% in Europe
- Infection levels seem to be falling in UK
What did the Prime Minister say?
The Prime Minister was speaking on a visit to Sidcup on Friday, where voters will elect a new MP in December after the death of former minister James Brokenshire.
He said: “I am seeing the storm clouds gathering over parts of the European continent.
“We have been here before and we remember what happens when a wave starts rolling in.
“The UK has built in a huge amount of protection thanks to the vaccine rollout and people’s willingness to come forward and get jabbed.
“The urgency of getting the booster jab is more evident than ever.”
He said there was no question that a wave of infection was coming across Eastern Europe.
Mr Johnson added: “We are seeing numbers rise in Germany very steeply.
“I am concerned about the Delta variant being passed between those who are vaccinated and indeed those who are double vaccinated.
“It is absolutely vital, if we are going to continue in the way that we are, that people get their boosters when they are called forward.”
What is the situation across Europe?
Analysis of data published by the European Centre for Disease Prevention and Control (ECDC) looked at the seven-day rate of new reported cases, as of 11 November.
It found that while the UK is still above most countries, it is not following the trend of other nations where rates are up week-on-week.
In Austria there are 766.2 cases per 100,000 people (up from 484.8 a week earlier), in the Netherlands there are 496.0, up from 334.7, and in the UK there are 362.6 cases per 100,000 people (down from 412.1).
In Germany there are 280.6 cases per 100,000 people, up from 180.8, and in France 98.5, up from 64.7.
Portugal has 81.5 cases per 100,000 people (up from 57.5), Italy 78.4 (up from 52.8), and Spain 42.8 (up from 28.9).
The World Health Organisation said coronavirus deaths rose by 10% in Europe in the past week, and last week an official declared that the continent was back at the epicentre of the pandemic.
What are levels like in the UK?
Austria is considering imposing a lockdown on unvaccinated people, the Dutch government is reportedly considering a limited two-week lockdown and German lawmakers are considering legislation that would pave the way for new measures.
New data from the Office for National Statistics also suggests infection levels are continuing to fall across the UK.
The figures show that about one in 60 people in private households in England had Covid-19 in the week to 6 November, down from one in 50 the previous week.
In Wales, about one in 45 people is estimated to have had Covid-19 in the week to 6 November, down from one in 40 the previous week.
In Northern Ireland, the figure is about one in 75 people, down from one in 65 the previous week.
In Scotland it is one in 85, down from one in 80 the previous week.
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