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People who are unjabbed but previously had the Delta Covid variant may have very little protection against Omicron infection, a lab study suggests.  

Austrian scientists tested the blood of those who had beat the older strain of the virus against the new super-variant to measure their antibody response.

They found only one out of seven samples produced enough of the infection-fighting proteins to neutralise Omicron.

It suggests that prior infection from Delta alone offers virtually no protection against catching Omicron — but the jury’s still out on severe illness.

Antibody studies look at one very specific part of the immune response to Covid and do not take into account T cell and B cell immunity, which are vital for protection against severe disease but more difficult to measure.

Most scientists believe people who have had Covid still enjoy some protection against serious outcomes, but immunity is known to wane significantly after six months. 

The latest study, by the Medical University of Innsbruck, found that if Delta survivors go on to get a vaccine they become ‘super-immune’, even against infection.

British experts reacting to the study said it highlighted the importance of getting a booster jab. The findings appear at odds with the low severity of cases in South Africa, which first alerted the world to Omicron.

South Africa’s epidemic already seems to have peaked with just 370 daily hospital admissions on average despite only a quarter of the population being vaccinated.

England’s chief medical officer Chris Whitty has attributed the country’s success to an antibody boost from a relatively recent Delta wave. 

The study comes as Nicola Sturgeon today cancelled large scale New Year celebrations in Scotland as she unveiled additional coronavirus restrictions to slow the spread of the Omicron variant — amid growing fears that England could be next.

The Scottish First Minister said the advice for Christmas Day remains unchanged, with people allowed to meet with family but urged to be cautious. But from December 26 for three weeks there will be attendance limits placed on live public events which will torpedo Hogmanay festivities.

The limits will not apply to private life events like weddings, but Ms Sturgeon said for indoor standing events the limit will be 100 people, for indoor seated events it will be 200 and for outdoor events 500 seated or standing. 

This chart shows how the blood samples of people who had received vaccines and and survived a previous Delta infection performed when exposed to Omicron in terms of producing neutralising antibodies, measured here as 'IC50', a measures of effectiveness. Any combination that failed to get higher than IC50 16 failed to produce enough antibodies to significantly fight off Omicron. These bars are averages based on all the samples of their respective combinations. It shows a previous Delta infection fails to provide any significant protection in terms of antibody production, but a combination of previous Covid infection and a vaccine provoked the best response

This chart shows how the blood samples of people who had received vaccines and and survived a previous Delta infection performed when exposed to Omicron in terms of producing neutralising antibodies, measured here as 'IC50', a measures of effectiveness. Any combination that failed to get higher than IC50 16 failed to produce enough antibodies to significantly fight off Omicron. These bars are averages based on all the samples of their respective combinations. It shows a previous Delta infection fails to provide any significant protection in terms of antibody production, but a combination of previous Covid infection and a vaccine provoked the best response

This chart shows how the blood samples of people who had received vaccines and and survived a previous Delta infection performed when exposed to Omicron in terms of producing neutralising antibodies, measured here as ‘IC50’, a measures of effectiveness. Any combination that failed to get higher than IC50 16 failed to produce enough antibodies to significantly fight off Omicron. These bars are averages based on all the samples of their respective combinations. It shows a previous Delta infection fails to provide any significant protection in terms of antibody production, but a combination of previous Covid infection and a vaccine provoked the best response

This chart on the right shows how antibodies from Delta (variant designation B.1.617.2) performed against  different Covid variants, from left to right Alpha (B.1.1.7) Beta (B.1.351), Delta, and Omicron (B.1.1.529). A IC50 level above 16 meant the antibodies were sufficient enough to significantly fight off the virus. The chart on the right shows the results for 'super-immune individuals, the bars on the left show the results for individuals infected than jabbed, against Delta and Omicron, and the bars on the right show persons vaccinated and then infected

This chart on the right shows how antibodies from Delta (variant designation B.1.617.2) performed against  different Covid variants, from left to right Alpha (B.1.1.7) Beta (B.1.351), Delta, and Omicron (B.1.1.529). A IC50 level above 16 meant the antibodies were sufficient enough to significantly fight off the virus. The chart on the right shows the results for 'super-immune individuals, the bars on the left show the results for individuals infected than jabbed, against Delta and Omicron, and the bars on the right show persons vaccinated and then infected

This chart on the right shows how antibodies from Delta (variant designation B.1.617.2) performed against  different Covid variants, from left to right Alpha (B.1.1.7) Beta (B.1.351), Delta, and Omicron (B.1.1.529). A IC50 level above 16 meant the antibodies were sufficient enough to significantly fight off the virus. The chart on the right shows the results for ‘super-immune individuals, the bars on the left show the results for individuals infected than jabbed, against Delta and Omicron, and the bars on the right show persons vaccinated and then infected

These charts show how two doses of Moderna's vaccine performed and the right shows the same for two doses of AstraZeneca, the numbers in the top right of each graph indicate how many samples maned to exceed the IC50 threshold

These charts show how two doses of Moderna's vaccine performed and the right shows the same for two doses of AstraZeneca, the numbers in the top right of each graph indicate how many samples maned to exceed the IC50 threshold

These charts show how two doses of Moderna’s vaccine performed and the right shows the same for two doses of AstraZeneca, the numbers in the top right of each graph indicate how many samples maned to exceed the IC50 threshold

The chart on the right shows how one dose of AstraZeneca and Pfizer performed  and the right two doses of the Pfizer jab

The chart on the right shows how one dose of AstraZeneca and Pfizer performed  and the right two doses of the Pfizer jab

The chart on the right shows how one dose of AstraZeneca and Pfizer performed  and the right two doses of the Pfizer jab

In the samples of the blood of Delta survivors, which contained antibodies from the prior infection, Austrian researchers found only one out of seven samples tested managed to inhibit Omicron.

WHAT DOES THE EVIDENCE SHOW ABOUT VACCINE EFFECTIVENESS AGAINST OMICRON? 

1. South Africa

Real-world evidence from 78,000 Omicron cases in South Africa suggests just two doses of Pfizer’s vaccine still provides 70 per cent protection from hospitalisation and death six months later.

But immunity against infection could be below 30 per cent, according to the analysis by the South African Medical Research Council.

South Africa is not yet rolling out boosters widely so the real-world evidence on their effectiveness will likely come from Britain.

Experts in the UK say they need to wait until there are 250 Omicron patients in hospital before they can give accurate estimates – currently there are 104. 

2. Sweden

A separate study by researchers in Sweden found that while there is a drop in the body’s ability to neutralise Omicron it is not seen in everyone and is a smaller drop than feared.

Scientists at the Karolinska Institute in Stockholm found there was an average seven-fold drop in neutralisation potency against Omicron.

But it varied between a 1-fold and 23-fold reduction among patients. 

Researchers said almost all blood samples evaluated had some form of neutralising antibody response against Omicron.

Their findings were based on recent blood samples from 17 people in Stockholm, compared to 17 hospital workers who were previously infected with the original Wuhan strain. 

Benjamin Murrell, an assistant professor in computational biology, virology and immunology and one of the researchers behind the study, said this is ‘certainly worse than Delta’ but is not ‘as extreme as we expected’. 

He said the AHRI study reported a ‘much more substantial average reduction’ but noted ‘what is common is that neutralisation is not completely lost for all samples, which is positive’. 

3. Germany

A third set of results shared by researchers in Germany found neutralising antibodies from two doses of the vaccines used in the UK are ineffective against the strain. 

Dr Sandra Ciesek, a virologist at the German Center for Infection Research, tweeted laboratory findings, which have not yet been published, show that six months after two doses of Pfizer or Moderna, or a first dose of AstraZeneca and second dose of Pfizer, there was no neutralising antibodies present that could protect against Omicron. 

And even three months after being boosted with the Pfizer jab, people had just 25 per cent protection from neutralising antibodies against Omicron, compared to 95 per cent protection at the same point against Delta. 

Dr Ciesek said this translates into a 37-fold reduction against Omicron compared to the Delta strain. 

The findings confirm that developing new vaccines that target Omicron ‘makes sense’, she said.

But Dr Ciesek noted that the results ‘cannot say anything’ about whether people are still protected from severe illness, which other parts of the immune system play a key part in warding off. 

4. Pfizer

Pfizer’s results are based on a laboratory study using the blood of 20 people, who were either double-jabbed three weeks earlier or triple-jabbed one month earlier with its vaccine.

The results showed the third dose may provide a ‘more robust protection’, triggering a 25-fold jump in antibody levels. 

Pfizer, which manufactured the jab with German partner firm BioNTech, said the levels equated to a ‘high efficacy’ based on data against other variants. 

A booster jab offered a boost in antibody levels that are ‘comparable to those observed’ for the original Wuhan virus after two doses, the company said.

The level of neutralising antibodies against Omicron after three jabs was 154, compared to 155 against the Wuhan strain after two jabs.

But the figure was 60 per cent lower than levels seen for three doses against Delta. 

5. Moderna 

A booster Moderna Covid vaccine should offer high protection against Omicron, according to lab results released by the company today.

Scientists tested the new variant against the blood of people vaccinated with three doses of its vaccine and measured their antibody levels.

The scientists found a third dose increased the level of neutralising antibodies against Omicron by around 37-fold compared to waning immunity from two doses.

Moderna said this preliminary data was ‘reassuring’, though it added that it will continue to develop a jab specific to the variant.

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This essentially means the antibodies did not recognise Omicron as a threat due to its heavily mutated nature compared to the Delta variant. 

And the same was true for those who received two doses of the Oxford AstraZeneca jab, with zero out of the 20 sample generating sufficient antibodies to beat Omicron.

Two does of the Pfizer jabbed fared better, with nine out of 20 samples producing enough antibodies to fight off the new Covid variant before it causes infection.

A test for two doses of the Moderna jab showed only one out of 10 was successful in generating antibodies against Omicron. 

But the best result overall was seen in five samples taken from those who had both survived a previous Covid infection and then later got a vaccine, a group of people the researchers dubbed the ‘super-immune’.

These individuals’ antibody response against Omicron was roughly four times greater than even the Pfizer and AstraZeneca vaccine combination.

Samples taken from five people with opposite combination, getting a vaccine, then a Covid infection, also produced an antibody result roughly twice as better than a jabs alone.

However all the findings for Covid vaccines, prior Delta infection, and the ‘super-immune’, showed an incredible reduction in effectiveness against Omicron compared to other Covid variants. 

Professor Lawrence Young a microbiologist from the  University of Warwick said although the study has small numbers it added to research demonstrating Omicron’s ability to dodge immunity. 

‘This paper with small numbers of samples confirms data from previous studies and further emphasises the immune-evasive properties of the Omicron variant,’ he said.

He added that while it was ‘dangerous’ to infer any findings from the study, he said it reinforced the importance of getting a booster, and those that do would likely enjoy similar Omicron protection as the study’s ‘super-immune. 

‘It’s dangerous to extrapolate what this data means for immune protection in vaccinated individuals other than reinforcing the value of booster vaccination – which is likely to be similar to the super immune individuals in this study,’ he said.

The microbiologist also commented on the seeming disparity between the study’s findings and the South African experience of Omicron. 

At a glance the findings appear at odds with the with the low severity of cases in South Africa, which first alerted the world to the new Covid variant, which has ben partly attributed to an antibody boost from a relatively recent Delta wave. 

Professor Young  this could be due other non-antibody parts of the immune system, such as T-cells, which are vital for protection against severe disease but more difficult to measure, though he added demographic factors could also be at play. 

‘Perhaps this T cell response explains the situation in South Africa, although I think other factors like the younger average age of the population is also playing a part,’ he said. 

 Professor Ian Jones a virologist from the University of Reading also discussed the limitations of the study. 

He said that since the study measured Omicron’s ability to infect but not how severely ill those infected might become, several questions about how seriously to deal with the new Covid variant remained unanswered. 

‘They only measure virus entry into cells, not disease so the current dilemma of planning for a serious outcome to the current wave remains in place,’ he said. 

‘The assays measure neutralising antibodies, which are only one part of the overall protective response.

‘Add in the data that Omicron appears not to infect lung tissue to the same degree and the, mostly anecdotal, reports that it is milder overall and the infection equals hospitalization argument remains unanswerable at the moment.’   

The UK has pinned its hopes on warding off Omicron on the rollout of Covid booster doses. 

While just under 29million Britons have now received a third Covid jab this still leaves 25million adults needing one to offer them the best protection from Omicron. 

The booster campaign, which was already underway before Omicron arrived in the UK in response to waning protection against Delta, has floundered since Boris Johnson pledged to turbocharge the programme. 

On December 13 the Prime Minister pledged to increase the number of boosters being administered to 1million-jabs-a-day in response to the threat posed by the Omicron variant. 

However the booster campaign has continually failed to reach this target in the week since its announcement, only getting close on December 18 when 940,606 third Covid vaccine doses were administered. 

The PM declared last night that there will be no more pandemic restrictions introduced yet despite massive pressure from experts who warn the NHS is at risk of being overwhelmed by Omicron.

Mr Johnson has admitted the decision was ‘finely balanced’ – with speculation that the Government could still need to act with a ‘circuit breaker’ before New Year if new crucial evidence due today and tomorrow show the situation deteriorating quickly.

This evidence include an assessment from an Imperial College team on the severity of Omicron.

However, it now looks too late to bring in any legal restrictions before December 25, with the Prime Minister having vowed to give MPs a say in advance on any new restrictions. 

There has been heavy criticism of the claim from SAGE modellers that deaths could reach 6,000 a day in the worst scenario, and although daily cases have been rising sharply and topped 100,000 on December 15 they are still short of the levels feared.

Commons Leader Jacob Rees-Mogg is understood to have urged the government to ‘trust people’ to respond to the alarm about the rapid spread of the new strain, rather than bringing back draconian laws.

But the move in Scotland to tighten curbs ahead of New Year will pile the pressure on Boris Johnson to do the same. 

Mr Johnson is under pressure from his scientific experts to act now but there has been heavy criticism of the claim from SAGE modellers that deaths could reach 6,000 a day in a worst case scenario, and although daily cases have been rising sharply and topped 100,000 on December 15 they are still short of the levels feared.

Ms Sturgeon appeared to fire a shot at the Prime Minister as she said ‘we know from experience that if we wait until the data tells us conclusively that we have a problem… it will already be too late to act to avoid that problem’.

Her announcements came after Rishi Sunak unveiled a £1billion bailout for stricken businesses as Mr Johnson sits on the fence over Covid curbs amid infighting among ministers and top scientists.

The Chancellor has announced grants of up to £6,000 for hospitality and leisure firms being crippled by a wave of cancellations following the emergence of the Omicron strain.

The taxpayer will also cover the cost of statutory sick pay for Covid-related absences for companies with fewer than 250 employees.

The move – which was given a broad welcome by industry – comes despite the PM declaring last night that there will be no more restrictions in England yet, defying massive pressure from experts who warn the NHS is at risk of being overwhelmed by the mutant strain.

Mr Johnson admitted the decision was ‘finely balanced’ – with speculation that the government could still need to act with a ‘circuit breaker’ before New Year if new crucial evidence due today and tomorrow show the situation deteriorating quickly. They include an assessment from an Imperial College team on the severity of Omicron.

However, it now looks too late to bring in any legal restrictions before December 25, with the premier having vowed to give restive MPs a say in advance.

Mr Johnson said the latest Omicron data will be kept under ‘hour by hour’ review, with the holding line coming after a long and ‘fractious’ Cabinet meeting, where ministers including Mr Sunak demanded more solid proof on the threat from the Omicron variant before signing off on further measures.

The PM is expected to be handed more data on the impact of Omicron today amid questions over the accuracy of SAGE modelling. 

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