Ireland needs to prioritise the elderly and vulnerable in the upcoming COVID-19 vaccine booster campaign, according to leading immunologist Kingston Mills.
Professor Mills says it "might make more sense" to wait for updated vaccines that protect against the Delta variant before rolling out a booster campaign to the wider population.
With the initial vaccine programmes nearing completion, Ireland and other countries are preparing to start giving some people a third vaccine shot in the autumn and winter.
The WHO has urged rich countries to hold off on booster campaigns until at least the end of September, in a bid to get more of the developing world vaccinated.
However, some countries such as Israel have already begun administering third shots to older and vulnerable people - with more countries set to follow in the coming weeks and months.
It comes as new studies looking at the Delta variant show the vaccines are effective at preventing severe disease but less effective at preventing transmission.
Prof Mills - Professor of Experimental Immunology at Trinity College Dublin - told On The Record there is now some evidence of "waning immunity" from COVID-19 vaccines, as is the case with all vaccines.
He said: “We do know there is some waning of immunity after the COVID-19 vaccines - it’s maybe not that dramatic against the original strain of the virus. But things have changed a lot since then.
“Each time there’s a variation in the virus, it makes it more difficult for the vaccine to prevent the infection.”
While there is some conflicting data so far about how much vaccine effectiveness drops over time, Professor Mills said “we can assume” there’s some drop-off.
However, he said this isn't surprising.
He explained: "If you look at the immunity against the Alpha variant, the waning immunity wouldn’t have been significant enough to warrant another booster at this stage.
"But with the Delta variant and possibly other ones… there’s a good case for boosting, especially those that would have weak immune responses… sooner rather than later.
“But I don’t there’s a need at this stage to boost everyone in the country.”
Updated vaccines
Companies such as Pfizer are currently developing and testing 'updated' versions of their vaccines aimed specifically at protecting against the Delta variant.
Prof Mills said: “They will need further testing before regulatory agencies will give approval… but it’s expected they’ll be ready before the end of the year.
"It might make more sense to actually wait for the majority of the population until those vaccines are ready.
“Then not only are you boosting the response, but you’re actually boosting it specifically against the Delta variant - so that would make some scientific sense.”
He says we'll see data from Israel soon about how effective third doses are proving.
Meanwhile, Prof Mills stressed that vaccines still offer strong protection against severe disease and hospitalisation.
He said the number of younger people currently in hospital - as well as the risk of long COVID- remains a "real, strong incentive" for young people to get vaccinated.
