London: Two doses of Pfizer and AstraZeneca COVID-19 vaccines generate lower levels of antibodies against the Omicron variant of the coronavirus, according to a study which suggests that people previously infected or vaccinated may be at increased risk of infection.
Researchers at the University of Oxford in the UK analyzed the impact of the omicron variant of concern on one of the immune responses generated by vaccination.
The still-to-peer-reviewed study, published Monday on the MedRxiv preprint repository, used blood samples from individuals who had previously received two doses of AstraZeneca or Pfizer vaccines, and a live virus isolate.
Researchers demonstrate a substantial decrease in neutralizing titers – a measure of the level of neutralizing antibodies generated in response to vaccination against or infection with COVID-19.
The results indicate that the Omicron variant has the potential to cause a new wave of infections, including those already vaccinated, the researchers said.
They noted, however, that there is currently no evidence of an increased potential to cause serious illness, hospitalizations or death in vaccinated populations.
These results are consistent with data recently released by the UK Health Security Agency, showing reduced efficacy of two doses of these vaccines against symptomatic illnesses due to the Omicron variant compared to Delta.
This efficacy was improved by the third dose of the vaccine, however, the researchers said.
“These data will help those who develop vaccines and vaccination strategies to determine the pathways to best protect their populations, and to convey the message that those who are offered a booster vaccination should take it,” said the professor. Gavin Screaton, Director of Medical Sciences at Oxford. Division and main author of the article.
“Although there is no evidence of an increased risk of serious illness or death from the virus among vaccinated populations, we must remain cautious, as a greater number of cases will always place a considerable burden on the systems. health, ”said Screaton.
The researchers noted that this data is important but is only part of the picture.
They only look at the neutralizing antibodies after the second dose, but don’t tell us about cellular immunity, and that will also be tested using stored samples once the tests are available, they said.
“It is important to note that we have not yet assessed the impact of a ‘third dose’ booster, which we know dramatically increases antibody concentrations, and it is likely that this will lead to a improved potency against the Omicron variant, ”said Matthew Snape, professor at the University of Oxford and co-author of the study.
“Vaccination induces many arms of our immune system, including neutralizing antibodies and T cells,” said Teresa Lambe, professor at the University of Oxford and author of the article.
“Real-world efficacy data has shown us that vaccines continue to protect against serious illnesses with previous variants of concern. The best way to protect ourselves in the future in this pandemic is to get vaccines from anywhere in the world. arms, ”Lambe added.
This story was posted from an agency feed with no text editing. Only the title has been changed.
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