The UK is facing a “tidal wave of Omicron” which is likely to cause “very many deaths”, according to Prime Minister Boris Johnson.

In a pre-recorded address to the nation on Sunday evening, said Britain “must urgently reinforce our wall of vaccine protection” as he set a new deadline of jabbing everyone over 18 by the new year.

Mr Johnson said scientists had discovered that being fully vaccinated is “simply not enough” to prevent the spread of the coronavirus mutation and that, without a lightning speed mass booster campaign, the NHS could be overwhelmed.

The announcement comes as the UK Covid alert level was raised to Level 4, up from Level 3, following a rapid increase in the number of Omicron cases being recorded.

The recommendation was made to ministers by the country’s four chief medical officers and NHS England’s national medical director following advice from the UK Health Security Agency (UKHSA).

The UK, as of Sunday, recorded a further 1,239 confirmed cases of the Omicron mutation, bringing the total number of cases to 3,137 – a 65% increase from Saturday’s total of 1,898.

The Oldham Times: Prime Minister Boris Johnson urged people to get their jabs (Kirsty O’Connor/PA)Prime Minister Boris Johnson urged people to get their jabs (Kirsty O’Connor/PA)

Boris Johnson issues booster warning to UK

Speaking from Downing Street on Sunday, the Prime Minister said: “Do not make the mistake of thinking Omicron can’t hurt you, can’t make you and your loved ones seriously ill.

“We’ve already seen hospitalisations doubling in a week in South Africa and we have patients with Omicron here in the UK right now.

“At this point our scientists cannot say that Omicron is less severe.

“And even if that proved to be true we already know it is so much more transmissible that a wave of Omicron through a population that was not boosted would risk a level of hospitalisation that could overwhelm our NHS and lead sadly to very many deaths.

“So we must act now. Today we are launching the Omicron emergency booster national mission, unlike anything we’ve done before in the vaccination programme, to get boosted now.

“A fortnight ago I said we would offer every eligible adult a booster by the end of January.

“Today in light of this Omicron emergency I’m bringing that target forward by a whole month.

“Everyone eligible aged 18 and over in England will have the chance to get their booster before the new year.”

Professor Tim Spector, from King's College London is the Principal Investigator of the PREDICT studies and the ZOE Covid Symptom Study app.

He has previously warned Brits that they need to be aware of additional symptoms not listed by the NHS.

The NHS currently lists three key symptoms of the deadly bug responsible for the global health crisis.

They are a persistent, newly developed cough, a fever or a high temperature, and a sudden loss of taste or smell.

But now Prof Spector has said: "People urgently need to know there are more than just the three classic symptoms.”

21 Covid symptoms to look out for as Omicron cases rise

Here is the full list of 21 symptoms to look out for according Prof Spector:

  1. High temperature (fever)
  2. Chills or shivers
  3. Persistent cough
  4. Loss or change of smell
  5. Loss or change in taste
  6. Headache
  7. Unusual tiredness
  8. Sore throat
  9. Sudden confusion
  10. Skin rash
  11. Changes in the mouth or tongue
  12. Covid fingers or toes
  13. Shortness of breath
  14. Chest pains
  15. Muscle pains
  16. Horse voice
  17. Diarrhoea
  18. Skipping meals
  19. Abdominal pains
  20. Runny nose
  21. Sneezing