With the arrival of Omicron on Irish shores, public health experts and politicians have said the State is in a race between the booster and the latest Covid-19 variant.
The presence of Omicron increased 10-fold in a week, accounting for 11 per cent of cases, according to estimates from public health experts.
More than 1.2 million booster doses have been administered, including 97,000 third doses to people who are immunocompromised, latest figures show. However, hundreds of thousands more are waiting to receive their jab.
Why are we getting booster vaccines?
Immunologists have said waning immunity from the primary two-dose Pfizer, Moderna and AstraZeneca jabs, and the one-dose Janssen vaccine, starts within months.
This can be seen through the number of breakthrough infections in Ireland. Between October 17th and November 20th, 48 per cent of confirmed cases of Covid-19 were in vaccinated individuals, according to the most recent report by the Health Protection Surveillance Centre (HPSC).
Adding to this, the fact that Omicron is more transmissible, and evidence is not yet clear on the efficacy of the primary vaccine course against it, an additional dose will give added immunity to recipients.
Who is eligible for booster vaccines?
The HSE is currently offering boosters to people aged 50 and older, those living in a nursing home or a long-term healthcare facility, healthcare workers, and people aged 16 to 49 with an underlying condition.
It is expected over 40s will become eligible for the third jab before the end of the year.
The HSE is currently finalising a plan on this, which is expected to be published this week, on either Thursday or Friday.
All members of the public aged over 16 will gradually become eligible for the third jab as the programme moves down the age groups.
When should I get my booster?
Minister for Health Stephen Donnelly on Monday announced that the gap between the primary course and the booster dose will be reduced to three months, from six.
Up until now, only those who received the one-dose Janssen vaccine were due to get a booster after three months.
This is a move that has been recommended by the European Medicines Agency (EMA), in light of the Omicron variant.
Which vaccine should I get and where can I get it?
The administered boosters were, up until last week, primarily the Pfizer variety.
However, the HSE has a stock of Moderna vaccines, another mRNA jab, which is due to expire at various dates in the near future.
To maximise all Covid-19 vaccines, vaccination centres will primarily use Moderna for booster doses for people aged 30 and older in the coming weeks, with younger people receiving the Pfizer jab.
Eligible individuals can receive their booster vaccine at vaccination centres around the country, some of which are operating on a walk-in basis, or at participating GPs or pharmacies.
Are boosters working?
Israel suppressed a fourth wave of coronavirus infections last summer, driven by the more transmissible Delta variant, by giving a third booster dose to people aged 12 and older along with public-health measures.
In Ireland, the early evidence is also promising. The incidence of Covid-19 in the over 75s has decreased in recent weeks, a change which the National Public Health Emergency Team (Nphet) said may be attributable to the rollout of boosters.
Do we have capacity for a booster campaign?
Unlike the initial vaccine campaign, supply is not a constraining factor, according to the HSE. Instead, the issue is resources.
Many healthcare workers have resumed their primary roles, having previously been redeployed in the vaccination programme.
As the HSE finalises its latest plan, the focus is now on increasing capacity to the levels seen in the early phase of the programme, which will likely see these workers being seconded back to the vaccination programme.
Mr Donnelly has also said consideration is being given to extending opening hours of vaccination centres, increasing the role of pharmacists and GPs and re-opening pop-up vaccine clinics.
