As the current wave of Covid-19 continues to cause disruption, focus has begun to shift to whether more people should be eligible to receive a second Covid-19 booster vaccine.
Taoiseach Micheál Martin has said the second booster, for most a fourth dose, would be a “key weapon” against the virus in the autumn period. So who can currently get a second booster, how effective are they, and what approach have other countries taken?
Who can currently get a second booster?
Anyone aged over 64 or who is immunocompromised can currently receive a second booster vaccine. There must be at least four months between someone receiving their first and second booster, or between a Covid-19 infection and a second booster.
The National Immunisation Advisory Committee (Niac), which provides expert advice to the Government on vaccines, recommended that mRNA vaccines, such as Pfizer-BioNTech and Moderna, should be used for the booster shots.
Any further expansion of the second booster rollout to younger age cohorts will depend on a recommendation from Niac, which is currently considering the issue.
Three-quarters of adults have received at least one booster dose, according to figures from the Health Protection Surveillance Centre. A little more than half of the people eligible for a second booster have received the additional doses. Take-up among the immunocompromised to date is lower than a third of those eligible, which has been a point of concern for health service officials.
What are other countries doing?
Many other countries are offering a second booster vaccine to older generations and the immunocompromised, given both face greater health risks from the virus.
In the United States, the Centers for Disease Control and Prevention recommends a second booster for adults aged 50 and older, as well as anyone who is immunocompromised. Britain is offering a second booster dose to adults aged 75 or older, residents in nursing homes and those with weaker immune systems.
What do the studies say?
Israel was the first to offer a second booster to those aged over 60 and healthcare workers at the start of this year. Initial academic studies of the extra booster there show it provides more protection against severe illness compared with those who had only received one booster shot.
The latest Niac paper examining data around healthcare workers in Israel suggested younger, healthy people may get less benefits from the extra shot, where there is a shorter gap between the dose and an initial booster. The paper said younger age groups who got a second booster four months after their first one saw only “marginal benefits”, compared with those in at-risk groups such as older generations.
When will Niac issue advice?
As an expert group at arm’s length from the Department of Health, there is no set timeline for Niac to issue a recommendation around second booster shots. After Niac makes a recommendation the Government will decide whether to adopt the advice. The Health Service Executive would then be responsible for incorporating any changes into the vaccination programme.
At present, people can get vaccinated through some General Practitioners and pharmacists, as well as at vaccination centres. However, the centres are operating on a much smaller scale than at the height of the initial vaccine rollout.
