Infection with Omicron variants of COVID does not increase our immunity against further infection, even in people who have been stabbed three times, according to a new analysis.
The finding could explain why so many people have been infected a second time in time Omicron waves, even with Omicron itself.
Professor Rosemary Boyton, an infectious disease immunologist at Imperial College in London, who leads research on COVID in healthcare workers in the UK, said: “Being infected with Omicron does not provide an increased likelihood strengthens immunity against future re-infection with Omicron.
The results suggest that Omicron contamination will not necessarily increase protection against sub-variants BA.4 and BA.4 of COVID is currently on the rise in the UK.
However, the study only looked at the risk of infection COVID – continue vaccination to provide good protection against severe illness and death.
The study took blood samples from more than 700 medical staff in London, who have been monitored since March 2020. All had received three doses of the COVID vaccine but had different infection histories.
It allows researchers to investigate the “boosting” effect of different COVID infections, while also looking at the roles of different parts of the immune system: antibodies, B cells, and cells T.
The emerging picture is that the ability to protect against infection with further variants of COVID varies depending on a person’s infection status and vaccination history – a process described as “a hallmark of COVID-19″. Immunostimulation”.
They found people who had never had COVID but were infected with Omicron after three doses of the vaccine had good B and T cell immunity in laboratory tests against earlier variants such as Alpha and Delta – but less protective against Omicron.
But previous infection with other variants also had little effect on immunity to Omicron.
People infected with Alpha earlier in the pandemic had less antibody responses against Omicron. And their Omicron infection then didn’t boost their overall immune response.
Co-investigator Professor Danny Altmann, also at Imperial, said: “We found that Omicron is not a benign natural vaccine immune booster as we might have thought, but it is one particularly stealthy immunosuppressants”.
Omicron “flys under the radar, so the immune system can’t remember it,” he added.
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Lessons learned from COVID-19
This finding blows away the idea of ”herd immunity” building in populations over subsequent pandemic waves.
Even so, the pattern globally – at least for now – is that subsequent waves of COVID variants are causing fewer hospitalizations, fewer illnesses and deaths.
This suggests that despite people’s history of infection or vaccination, there is generally increasing immunity against severe COVID.
But the power of Omicron’s immune evasion, and the fact that new sub-variants are evolving, do not guarantee that trend will hold, the Imperial University team argues.
“One concern is that Omicron may be able to mutate deeper into a more pathogenic strain, or become better able to bypass vaccine protection,” said Professor Boyton.
“In this case, people who already have an Omicron infection will be less able to fight off future infections depending on their immune markers.”
