THE EUROPEAN CENTRE for Disease Control (ECDC) and the European Medicines Agency (EMA) have said that it is “too early” to consider using a fourth dose of mRNA Covid-19 vaccines in the general population.

It comes after the National Immunisation Advisory Committee (NIAC) today recommended that people aged 65 and older and those who are immunocompromised should receive a second mRNA booster dose.

In a joint statement, both agencies said that for adults “below 60 years of age with normal immune systems, there is currently no conclusive evidence that vaccine protection against severe disease is waning or that there is an added value of a fourth dose”.

However, the ECDC and EMA agreed that a fourth dose (or second booster) can be given to adults 80 years of age and above, after reviewing data on the higher risk of severe Covid-19 in this age group and the protection provided by a fourth dose.

“There is currently no clear evidence in the EU that vaccine protection against severe disease is waning substantially in adults with normal immune systems aged 60 to 79 years and thus no clear evidence to support the immediate use of a fourth dose,” the agencies said.

The ECDC and EMA warned that it may become necessary to consider a fourth dose in this age group, however, if the epidemiological situation changes.

Evidence on the effects of a fourth dose comes largely from Israel, the agencies said, where data indicate that a second booster given at least four months after the first booster “restores antibody levels without raising any new safety concerns”. 

Data also suggests that a second booster provides additional protection against severe disease, although the duration of the benefits is not yet known and the evidence is still limited.

Second booster

Health Minister Stephen Donnelly said he has accepted the recommendation made by the National Immunisation Advisory Committee (NIAC) last night to the Chief Medical Officer Dr Tony Holohan.

Dr Holohan has endorsed the recommendations. The booster campaign will not begin straight away, however, as the Department of Health and the HSE now need to put the advice into action. 

Donnelly said: “I welcome today’s update to Ireland’s vaccination programme. Covid-19 vaccines have achieved extraordinary success in preventing severe disease, hospitalisation and death.

“These vaccines continue to have a very good safety profile with hundreds of millions of doses administrated globally.”

In a statement to The Journal, a spokesperson for the HSE said: “As with all phases of the vaccination programme to date the HSE implements the recommendations from the National Immunisation Advisory Committee (NIAC) and guidance from the Chief Medical Officer.”

“The HSE is working to put plans in place to enable the extension of the programme in a safe and timely manner,” the spokesperson said.

Ireland uses two mRNA Covid vaccines – Pfizer and Moderna. 

NIAC recommended a second mRNA booster dose for people aged 65 and older, meaning this would be their fourth dose if they received a two-dose mRNA vaccine initially. 

Anyone aged 12 and older who is immunocompromised is also recommended to receive a second booster dose, making this their fifth dose overall.

Most vaccinated people who are immunocompromised would have received their initial booster doses, an additional jab to offer better protection and then a booster dose on top of that. NIAC has now recommended a further booster dose. 

The group also recommended that people aged 5-11 who are immunocompromised should receive a total of three vaccine doses.

Period between doses

Speaking on RTÉ radio’s Morning Ireland, Donnelly said the advice is that there should be a six-month period between this additional booster dose and the previous booster dose, but that a four-month time gap might be suitable in some cases. 

NIAC reiterated its previous recommendations for pregnant people to be offered mRNA vaccines at any stage of pregnancy if they have not yet been fully vaccinated.

The committee said it will “continue to recommend that people get and complete their primary vaccine course and booster shot if they haven’t already done so”.

“This is irrespective of a history of a previous COVID-19 infection.”

Minister Donnelly said unvaccinated or not fully vaccinated people continue to be “disproportionately affected” by illness, accounting for around one-third of Covid hospitalisations despite comprising a small percentage of the population.

He has asked NIAC to continue examining the evidence around the benefits of a second booster dose for other cohorts of the population. 

With reporting from Jane Moore