Antibodies from Pfizer vaccine may be up to 40 times less effective against Omicron, first lab tests suggest

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Antibodies from the Pfizer vaccine may be up to 40 times less effective against Omicron than the original COVID strain, the first lab tests on the new variant in South Africa have shown.

But while its ability to escape vaccine antibodies is significant, it’s not complete, and that’s good news, says Professor Alex Sigal, virologist at the Africa Health Research Institute, who led the research.

The study found antibodies from people who had been vaccinated as well as naturally infected with COVID were significantly more effective against Omicron – suggesting boosters may bring a significant benefit.

Its ability to escape the vaccine was between five and 10 times better than the Beta variant, which was also first reported in South Africa and previously had the best ability to evade the jab.

Professor Sigal, who heads up the team conducting the tests, believes it’s likely Omicron has both an immune escape and a transmission advantage over other variants.

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The study is very limited, having looked at live Omicron virus grown in the laboratory tested against blood samples from just 12 vaccinated people.

As such, it can’t tell us much about how effective vaccines will be against preventing infection, or onward transmission of Omicron in the real world.

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It’s valuable in showing that the impact of the variant is significant – but also that vaccines will still give us some protection. And boosters could give us significant protection.

Analysis by Tom Clarke, science and technology editor

This is what the data scientists have been waiting for ever since the Omicron variant was first discovered. It is very preliminary, and the numbers are subject to change. But those numbers are significant.

In people vaccinated against COVID-19 with two jabs of the Pfizer vaccine, the ability of their antibodies to neutralise Omicron was reduced by between 20 and 40 times compared to the original COVID variant against which all our vaccines are made.

It’s a huge reduction compared to variants that we have seen before. The Beta variant (previously known as the South Africa variant) was one of the strongest variants showing this “immune escape” but based on this analysis the Omicron variant is five to ten times better at evading antibodies.

While the effect observed in this study is significant, it’s a lot better than some immunologists had feared. Some were privately worrying that vaccines may have no impact against Omicron at all.

“We saw a lot of escape,” said Alex Sigal at the Africa Health Research Institute in Durban, who led the study. “But I think the news is pretty good.”

The fact antibodies from vaccines still recognise Omicron is significant. Especially as there are other parts to the immune system like T-Cells which could work against it too.

But the most promising finding is the fact that people who had been infected with COVID-19 previously, as well as being vaccinated, had much improved protection against Omicron.

This would indicate that in places like South Africa, where infection rates have been high in the past, the impact of Omicron could be reduced. It also bodes well for booster vaccination programmes like the one in the UK.

More studies, on larger numbers of people, will be needed to confirm these results. But they are the first direct evidence we have of how much of a challenge Omicron might turn out to be.

It comes after an earlier warning that the Omicron variant may be more transmissible than Delta, with a spokesman for Boris Johnson saying: “The prime minister said it was too early to draw conclusions on the characteristics of Omicron but early indications were that it is more transmissible than Delta.”

A total of 437 cases of Omicron have been identified as of Tuesday – 333 in England, 99 in Scotland, five in Wales and none so far in Northern Ireland – an increase of 101 in 24 hours.

Health Secretary Sajid Javid told MPs that cases of Omicron in people without any travel history have been confirmed in the UK, meaning it is now being transmitted within the community.

Omicron’s ability to cause severe disease is not yet clear.

Dr Anthony Fauci, the top US infectious diseases expert, has said initial evidence suggests the variant could be less severe, with fewer hospital admissions and less need for ventilators.

But he also warned that scientists will only have enough data to make more definitive conclusions in a few weeks.