AN IMMUNOLOGIST HAS said the HSE missed an opportunity to get more people in the habit of receiving winter vaccinations.

This is because the current advice does not encourage millions to get a Covid booster, despite being eligible.

The autumn-winter booster is currently only being offered to select groups: people age 50 or older, age 5 or older with a weak immune system, age 5 to 49 with a condition that puts them at high risk of serious illness, and healthcare workers.

People age 18 to 49 are excluded from this advice, but can still request a vaccine by speaking to their GP or pharmacist about their “reasons for wanting a booster”.

However, The Journal has spoken to several people in this age bracket who were turned down after requesting the vaccine, being told they were ineligible, despite not having had a recent booster or infection.

DCU’s Professor Christine Loscher said:

I know [this age bracket's exclusion from the advice] is to do with the fact that the risk over a certain age is higher in terms of the severity of a Covid infection, and we know Covid hospitalisations are usually higher over a certain age.

“I can understand the rationale for it, but I still think that it’s very early days in terms of trying to get people on board with Covid boosters and that limiting it is not the best approach.”

Loscher’s advice for people aged 18 to 49 is to request the booster, especially those who have yet to receive an updated vaccine or who have not had a recent infection.

Last year’s booster contained the original strain of the virus responsible for Covid as well as either the Omicron BA.1 strain or BA.4-5 strains, meaning it offered increased protection against more recent variants and their offshoots.

This year both the Pfizer/BioNTech BA.4-5 booster and one targeting the newer XBB.1.5 variants are on offer, as well as two non-mRNA vaccines (Novavax and VidPrevtyn Beta).

“The [Pfizer] booster is more specific to the circulating strains – even if it’s not specifically for this strain, it’s nearer to it than the original vaccine,” Loscher explained.

Antibodies waning

She added that we know that antibody levels will wane over time and that it is clear that the vaccines boost this, offering durable protection against severe disease.

Scientific opinion is often split on the topic of repeated Covid boosters for the entire population.

Preventing severe illness is the primary aim of vaccines, but in younger age groups with no risk factors, the chance of severe disease is low. This means that for people who have received their primary course of vaccines, a previous – ideally updated – booster, as well as a Covid infection, this ‘hybrid’ immunity is expected to protect well against severe illness. Some argue that how much a booster would improve this could be marginal.

However, a booster will also – for a limited time, dependent on factors such as a person’s own immune response and the variants in circulation - protect against infection and, if an infection does occur, reduce the chance of onward transmission by decreasing the viral load an infected person carries.

Advocates say that this is an important factor during the winter months when the virus is in high circulation, in addition to the fact that the risk of severe illness or developing Long Covid is not zero.

Also, as Covid continues to evolve, annual boosters just like the flu booster are set to become the norm.

Loscher also questioned why similar criteria to the influenza vaccine were not applied to the Covid booster.

The recommended groups for the Covid booster are more narrow than the scope of the flu jab. For example, household contacts of people at higher risk of serious illness can avail of a free flu vaccine.

Those not in the groups eligible for a free shot can pay for it, generally costing in the region of €35.

The differences in criteria can be partly explained by how the two viruses behave differently.

There is a chance that people of all ages will become seriously ill due to a Covid infection, but influenza is often considered the riskier of the two for younger children, which is why children age 2 to 12 are eligible for a free flu shot.

“I have a problem with the flu vaccine not being free for everybody,” Loscher said.

I think by only making this available for certain cohorts you don’t get the kind of engagement that you could get – in the same vein as the Covid vaccine only being made available for certain cohorts.

When asked about the rationale for not offering this winter’s Covid booster to people age 18 to 49, the HSE referred to National Immunisation Advisory Committee (NIAC) advice.

This states that “those healthy aged 18-49 years who have availed of the offer of a second booster dose additional booster vaccines are not routinely recommended” but does not offer more detail.

“Meanwhile, the HSE is urging every eligible person to get vaccinated against flu and Covid-19 urgently amid concern over an expected imminent rise in winter viruses. This is particularly important for people with long-term health conditions and healthcare workers,” the statement added.

The HSE expressed concern in recent weeks that uptake of both flu and Covid vaccines remains low, in particular healthcare workers.

As of 1 November, the HSE said just 11.5% of HSE-employed healthcare workers had availed of the Covid booster and 24.3% of the flu vaccine.

This is far short of the 50% target for Covid and 75% for flu.