‘NOVIDs’ may benefit more from a booster due to their lack of hybrid immunity

COVID numbers are rising after a bit of a lull, says University of Melbourne clinical epidemiologist Professor Nancy Baxter, and “things are about to take off.”

Evidence of a new wave includes a 13.5% rise in COVID cases across the country this past week, and a 6.1% increase in hospitalisations last week, she says.

Recent research has shown that the longer it has been since someone had their last COVID vaccine, the higher their risk of developing severe disease if they contract COVID.

But the vast majority of Australians are not up to date with recommended boosters.

According to Professor Baxter there are still a lot of people in the community who are eligible for another booster, who would likely benefit from one, and for whom it is recommended by ATAGI, who have gone more than six months without a vaccine—and that includes people over 65 and those living in aged care facilities.

“Importantly this extends to residential aged care, which frankly I find very concerning,” Professor Baxter says. “When you look at individuals in residential aged care, only 30.6% are up to date with ATAGI recommendations.”

Put another way, almost 70% of residents in aged care are still at particularly increased risk without having had a vaccine dose or infection in the last six months.

Alarmingly, only 9.1% of eligible aged care residents have had a 2023 booster dose of a COVID-19 vaccine, according to Department of Health data.

This is particularly worrying given a new wave is on the horizon.

Professor Baxter says that while the ‘major bang for your buck is in that older population,’ it’s important to think of different age segments separately.

“Risk increases after age 50—so your 50-year-old will be more at risk than your 18-year-old and your 64-year-old will be at even higher risk, so we should be talking about risk differently in that group,” she says, adding that 18 to 29-year-olds also have a different risk to benefit ratio due to higher risk of side effects from the booster in that group.

Another segment of the 18-64 age group who might particularly benefit from a booster are the NOVIDS; those who’ve never had COVID.

That’s because hybrid immunity plays a big part in the risk component underpinning ATAGI’s recommendations, with meta-analyses showing added protection of vaccine plus past infection.

“Vaccination is more important in people who have never had COVID, if it’s been 6 months from their last dose,” Professor Baxter says.

She also notes that there are also many people in the younger, lower risk age groups who have not ‘been boosted at all.’

“There are a lot of people who are still at just two doses, and it’s a game changer, that third dose. They do need that third dose,” she says.

To that end, Professor Baxter highlights the importance of being honest with patients that recommendations will continue to change.

To hear the latest COVID update from Professor Nancy Baxter, listen to the latest Going Viral episode.