Omicron variant, study data: symptoms, third dose, reinfections

Oxford researchers report “possible increase in vaccinated or cured cases”

The Omicron variant does not appear capable of causing more severe symptoms in covid sufferers or causing more deaths. Infections could increase among those already cured or vaccinated. The third dose of the vaccine is absolutely essential. While the first death linked to the variant is reported in Great Britain, the conclusions of a study conducted by researchers at the University of Oxford arrive. The results were disseminated on the ‘MedRxiv’ pre-print platform.

The new Omicron variant of the coronavirus produces “a substantial drop in neutralizing titers, a measure of the level of neutralizing antibodies generated in response to anti-Covid vaccination or Covid-19 infection”. Therefore, “although there is no evidence of an increased potential for Omicron to cause severe disease or death, a growth in infections is likely in previously infected or immunized people. “

The authors analyzed the effect of an Omicron ‘version’ live virus isolate on blood samples from people who had received two doses of the Oxford / AstraZeneca or Pfizer / BioNTech vaccine as part of the Com-Cov study. They then observed “a substantial decrease in neutralizing titers”, suggesting that “Omicron has the potential to drive a further wave of infections even among vaccinated people, although there is currently no evidence of an increased potential to cause severe Covid. hospitalizations or deaths in immunized populations “.

“These results – explain the scientists – are in line with data recently published by the UK Health Security Agency, which show a reduced efficacy of two doses of the vaccine against the symptomatic disease associated with the Omicron variant compared to Delta”. However, scholars are keen to emphasize that “this efficacy was improved by a third dose of the vaccine”. For this reason, “increasing vaccination adherence among non-immunized and encouraging dose boosters remain the priority to reduce transmission levels and the potential burden of severe disease.”

“These data will help vaccine developers and vaccination strategies define approaches that best protect populations, and convey the message that those who are offered a booster dose should do so,” said Gavin Screaton, Head of Medical Sciences at Oxford. and lead author of the study. “Although there is no evidence of an increased risk of serious illness or death” due to Omicron “among vaccinated populations, we must remain cautious – he warns – as a greater number of cases will continue to represent a considerable burden on health systems “.

“These data are important, but they only describe part of the picture,” says Matthew Snape, professor of pediatrics and vaccinology at Oxford and co-author of the paper: “They look at the levels of neutralizing antibodies after the second dose of the vaccine, but not at immunity. This will also be evaluated once the tests are available, “he says. Furthermore, he adds, “It is important to highlight that we have not yet evaluated the impact of a third dose” of the vaccine, “that we know to significantly increase antibody concentrations. And it is likely that” the booster “will lead to greater potency against the variant. Omicron.

“Vaccination activates multiple arms of our immune system, including neutralizing antibodies and T cells – recalls Teresa Lambe, professor of vaccinology at Oxford and author of the research – The data on efficacy in the real world have shown us that vaccines continue to protect from serious illnesses “linked to” previous variants of concern “of SARS-CoV-2. “The best way to protect ourselves in this pandemic – he assures – is to get vaccinated”.