Wastewater detections of BA.4/BA.5 have more than tripled since late May, rising from 5 to 17 per cent on June 23. It is expected to overtake another variant known as ‘stealth Omicron’, BA.2, in the “coming weeks,” a health department spokesman said. “This is in line with similar patterns in NSW and Queensland,” he said.“The Department of Health anticipates the prevalence of BA.4/BA.5 in Victoria is likely to result in an increase in cases – including reinfections – and hospital admissions. “This is because the strain has a greater ability than BA.2 to evade immunity provided by vaccination and earlier COVID-19 infection.“There is no evidence at this stage that the BA.4/BA.5 sub-lineage causes more severe disease, but the Department is closely monitoring the situation.”Deakin University Epidemiology Chair Professor Catherine Bennett said hospitalisations will increase as case numbers climb, with the strain more likely to infect people with vaccine or infection induced immunity than previous variants. “The sub variants keep these sort of rolling waves of rising cases, as they replace previous sub variants,” she said. “(BA.4/BA.5) establishes a high viral load quickly, so that it’s very infectious. “Initially, it was you could have Omicron, if you had just got over Delta. “Now, it’s you can have Omicron, even if you’ve just had Omicron, because there’s enough variability in these variants that are replacing each other. “That undermines that protection you’d otherwise have.”While there is a drop in the vaccine’s protection against infection when compared to previous variants, she said immunisation still significantly reduces the risk of hospitalisation and death. “The vaccines are still protecting us from severe illness and that is improved further with the booster,” she said. “You’re more than 80 per cent protected from severe illness.”Prof Bennett said strain-specific vaccines (the current Covid vaccine is based on the index strain) would be the next step, pointing to Moderna’s experimental Omicron booster. “It looks promising,” she said. “We’re just hearing those initial results from the first human trials, but that’s exciting for us. “It would be a closer fit. “Down the track, that’s what might break the cycle of just constant waves of related but different sub-variants that might just keep this thing lasting forever. “If the vaccines can catch up again, and we can knock Omicron on its head, and at least have better control … it will just start to bring numbers down enough that hospitalisations will become less common.”She said, with the rising risk of reinfection, it was important vulnerable people who contract Covid knew they are eligible for antivirals. “You have to have them within the first three to five days of symptoms,” she said. “So really important people know that and get onto that early.”
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