People who are vaccinated and then get infected with Omicron may be primed to overcome a broad range of coronavirus variants, early research, not yet peer-reviewed, suggests. A pair of studies showed that infection produced even better immune responses than a booster shot in vaccinated patients.
Teams from vaccine maker BioNTech SE and the University of Washington posted the results on preprint server bioRxix in recent weeks.
A Bloomberg report in BusinessTech says the findings offer a reassuring sign that the millions of vaccinated people who’ve caught Omicron probably won’t become seriously ill from another variant soon, even though the research needs to be confirmed, especially by real-world evidence.
Alexandra Walls, a principal scientist at the University of Washington who authored one of the studies, cautioned that people shouldn’t seek out infections in response to the findings.
Meanwhile, regulators are weighing whether COVID vaccines should be updated to target Omicron.
BioNTech’s team argued that the data indicate that offering people an Omicron-adapted booster shot may be more beneficial than multiple ones with the original vaccines.
The Washington research, conducted with Vir Biotechnology Inc, looked at blood samples from people who had been infected, then had two or three doses of vaccine, as well as those who’d caught the Delta and Omicron variants after two or three doses; others still had been vaccinated and boosted but never caught COVID.
A final group had only been infected with Omicron and never vaccinated.
Nose defences
One part of the study zeroed in on antibodies, the protective proteins tailored to recognise and neutralise invaders. It showed vaccinated people who’d caught omicron had antibodies that outperformed the others. They were even capable of recognising and attacking the very different delta variant.
“That indicates that we are at the point where we may want to consider having a different vaccine to boost people,” said David Veesler, an assistant professor at the University of Washington, who led the research.
The scientists were also able to identify antibodies in the nasal mucous of these patients, which could help them neutralise the virus as soon as it enters the body.
Both the Washington and BioNTech studies also looked at another piece of the immune system: B cells, a type of white blood cells that can kick in to produce a burst of fresh antibodies if they recognise a pathogen.
People who’d had an omicron breakthrough infection had a broader response from these useful cells than those who’d had a booster shot but no infection, the BioNTech team found.
Crucially, the Washington team also found that the broad response was missing in unvaccinated people who had caught omicron as their first exposure to the virus. This “would be a problem if a new variant that is significantly different emerged”, Veesler said.
Other researchers who reviewed the studies said the findings match up with the growing body of evidence for an immune boost from exposure to different virus variants via vaccination and infection. Scientists have also shown broad immune responses in people who caught delta after getting their shots.
Study 1 details
Distinct sensitivities to SARS-CoV-2 variants in vaccinated humans and mice
Alexandra Walls, Laura Van Blargan, Kai Wu , Angela Choi , Mary Jane Navarro, Diana Lee, Laura Avena, Daniela Montes Berrueta, Minh Pham, Sayda Elbashir, Marcos Miranda, Elizabeth Kepl, Max Johnson, Alyssa Blackstone, Kaitlin Sprouse, Brooke Fiala, Megan O’Connor, Natalie Brunette, Prabhu Arunachalam, Lisa Shirreff , Kenneth Rogers , Lauren Carter, Deborah Fuller, Francois Villinger, Bali Pulendran, Michael Diamond, Darin Edwards, Neil King, and David Veesler.
Post on bioRxiv on 9 February 2022
Abstract
The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019 has led to the development of a large number of vaccines, several of which are now approved for use in humans. Understanding vaccine-elicited antibody responses against emerging SARS-CoV-2 variants of concern (VOC) in real time is key to inform public health policies. Serum neutralising antibody titers are the current best correlate of protection from SARS-CoV-2 challenge in non-human primates and a key metric to understand immune evasion of VOC. We report that vaccinated BALB/c mice do not recapitulate faithfully the breadth and potency of neutralising antibody responses against VOC, as compared to non-human primates or humans, suggesting caution should be exercised when interpreting data for this animal model.
Study 2 details
Humoral immunity to SARS-CoV-2 elicited by combination COVID-19 vaccination regimens
Posted on bioRxiv on 13 May 2022
Abstract
The SARS-CoV-2 pandemic prompted a global vaccination effort and the development of numerous COVID-19 vaccines at an unprecedented scale and pace. As a result, current COVID- 19 vaccination regimens comprise diverse vaccine modalities, immunogen combinations and dosing intervals. Here, we compare vaccine-specific antibody and memory B cell responses following two-dose mRNA, single-dose Ad26.COV2.S and two-dose ChAdOx1 or combination ChAdOx1/mRNA vaccination. Plasma neutralising activity as well as the magnitude, clonal composition and antibody maturation of the RBD-specific memory B cell compartment showed substantial differences between the vaccination regimens. While individual monoclonal antibodies derived from memory B cells exhibited similar binding affinities and neutralising potency against Wuhan-Hu-1 SARS-CoV-2, there were significant differences in epitope specificity and neutralising breadth against viral variants of concern. Although the ChAdOx1 vaccine was inferior to mRNA and Ad26.COV2.S in several respects, biochemical and structural analyses revealed enrichment in a subgroup of memory B cell neutralising antibodies with distinct RBD-binding properties resulting in remarkable potency and breadth.