- Researchers used blood samples collected from Com-COV2 study participants who had received two doses of standard COVID-19 vaccination schedules to perform neutralisation assays using Omicron virus isolate
- Substantial fall in neutralising titres suggest that while there is no evidence of increased potential to cause severe disease, or death, increased infections in previously infected, or vaccinated individuals may be likely
- Increasing vaccine uptake among unvaccinated, and encouraging third doses, remain priority to reduce transmission levels and potential for severe disease
Using blood samples from individuals who had previously received two doses of the Oxford-AstraZeneca or Pfizer-BioNTech vaccines as part of the Com-COV study, and a live virus isolate, they demonstrate substantial decrease in neutralising titres – a measure of the level of neutralising antibodies generated in responses to vaccination against, or infection from, COVID-19.
The results, published on the pre-print server MedRxiv, indicate that the Omicron variant has the potential to drive a further wave of infections, including among those already vaccinated, although the researchers highlight that there is currently no evidence of increased potential to cause severe disease, hospitalisations or deaths in vaccinated populations.