Vaccine expert and chair of the Coalition for Epidemic Preparedness Jane Halton said Omicron would most likely replace Delta and become the dominant strain. “It’s arrived, and we’re now seeing it spreading not just in Sydney but elsewhere,” Halton told the Nine Network on Thursday. “I think the horse has bolted.” The news comes as Pfizer released a new study on Dec. 8, showing that the Pfizer vaccine booster was effective prevention against the Omicron variant. Halton said more work was being undertaken to determine how effective COVID-19 vaccines would be against the Omicron variant. “We all need to remember we don’t have a lot of data yet, but it certainly doesn’t look like [Omicron] is going to cause lots of severe disease and death,” she said. “That’s great if true, but it’s still early days, the WHO (World Health Organisation) is optimistic, so I think we all can be …