Frequently Asked Questions for vaccinators and health professionals

Extended COVID-19 vaccination and booster vaccination course for people who are immunocompromised

Frequently asked questions for vaccinators and health professionals.

Who is recommended to get an extended primary course?

The National Immunisation Advisory Committee have advised that people who are immunocompromised at the time of vaccination, due to disease or treatment, should receive one additional dose of a COVID-19 vaccine. The vaccine recommended is an mRNA vaccine.

This is not a booster dose.

An additional dose is recommended for these groups as an extended primary vaccination course, because they may not mount an adequate immune response to vaccination.

Who is considered to be immunocompromised?

The National Immunisation Advisory Committee (NIAC) have published guidance on which groups should be considered immunocompromised and offered the additional dose. Individuals in these groups at the time of vaccination should be offered the additional dose.

Please refer to their recommendations for a full list of those considered immunocompromised.

Why is an additional primary dose recommended for these groups?

There is evidence of an inadequate response to the COVID-19 vaccination course for these groups who are immunocompromised due to disease or treatment.

Those with immunocompromise with a suboptimal response to vaccines are particularly vulnerable to SARS-CoV-2 infections. They are more likely to get severely ill from COVID-19 and they are at risk of prolonged viral shedding.

While overall vaccine effectiveness against hospitalisation for COVID-19 was 86% in a US study, it was 90% among the immunocompetent compared with 63% in the immunocompromised. Forty to 44% of hospitalised breakthrough infections were in the immunocompromised.

A report from the European Centre for Disease Prevention and Control (ECDC) advises that additional doses should be considered for people with severely weakened immune systems as part of their primary vaccination.

Which COVID-19 vaccine is recommended as an additional primary dose?

One dose of an mRNA vaccine is recommended to complete the primary COVID-19 vaccine course. This advice is the same regardless of the vaccine(s) that was previously administered. In the HSE programme a dose of Comirnaty (Pfizer/BioNTech or Spikevax (Moderna) will be offered.

What is the vaccine dosage for the additional dose for the immunocompromised?

The recommended vaccine dosage should be administered. Read more about the dosage in the COVID-19 Clinical Guidelines

How soon after completing a course should the additional dose be given?

The mRNA vaccine should be given after a minimum interval of two months following the last vaccine administered.

Has the EMA authorised additional doses of COVID-19 vaccines?

The European Medicines Agency has authorised an additional primary dose of the same mRNA vaccine that the person received previously. However, the National Immunisation Advisory Committee recommends that an mRNA should be given as an additional primary dose regardless of the vaccine received previously.

Is there scientific evidence of benefit and safety?

Pfizer/BioNTech reported that data in individuals who received a third dose of Comirnaty® show a favourable safety profile and robust immune responses. The additional dose elicited significantly higher neutralising antibody titres against the initial SARS-CoV-2 virus (wild type), and the Beta and Delta variants, compared to the levels observed after the two-dose primary series.

Two reports of successful enhancement of immune response in solid organ transplant recipients have been reported. In a randomised controlled trial with 120 organ transplant recipients, median age 66 years, an additional dose of Spikevax® (Moderna) was given two months after the second dose and resulted in significant increases in antibody levels and neutralising antibody activity.

There is also preliminary evidence of the safety of giving a 3rd mRNA vaccine dose from Israel where a population-based booster programme of Comirnaty® administered to approximately one million people has already taken place. Data shared by the Israeli Health Ministry reported that no safety concerns were identified with similar safety profiles but lower rates of systemic and local reactions were reported than following the first or second doses.

Is it recommended to check serology before administering an additional primary dose?

No. This is not recommended. There is no agreed or recommended correlate of protection (there is no agreed or recommended antibody level above which you would not vaccinate, or below which you would vaccinate).

What is the recommended timing of the booster dose who have had laboratory-conformed breakthrough infection since they completed their COVID-19 vaccination course?

The National Immunisation Advisory Committee continue to advise the booster dose should be delayed for at least 3 months after the laboratory-confirmed COVID-19 infection was diagnosed. This is because a laboratory-confirmed COVID-19 infection is known to be highly immunogenic.

Serological testing prior to giving a booster dose is not recommended as mentioned above. If it cannot be established if an individual had COVID-19 infection in the time frame they may be vaccinated.

Should immunocompromised pregnant women receive an additional dose of an mRNA vaccine?

Yes. Immunocompromised pregnant women should be vaccinated. The additional dose can be given at any stage of pregnancy. 

What vaccine is recommended if someone has a contraindication to an mRNA vaccine?

For people aged 18 years and older, an additional adenoviral vector vaccine (COVID-19 Vaccine Janssen®) can be considered for those with a contraindication or precaution to an mRNA vaccine. For those aged 12-17 years of age, discuss with an allergist/immunologist.

Will those with immunocompromise need a booster dose of COVID-19 vaccine?

The National Immunisation Advisory Committee now recommend that those with immunocompromise will require a further booster dose of COVID-19 vaccine.

The booster dose should be given after an interval of at least three months following the 3rd dose of an authorised COVID-19 vaccine schedule which is recommended for those with immunocompromised.

What age group is being offered the booster dose?

People aged 12 and older with an immunocompomise are being offered the booster dose.

Why aren’t other people with underlying conditions recommended to get an additional primary dose of COVID-19 vaccine?

A third primary dose of an mRNA vaccine is only recommended for those with immunocompromise in order for them to complete primary immunisation. This is not a booster dose, but an additional dose to allow them to mount an adequate primary immune response to vaccination.

Other groups do not have a suboptimal response to vaccines and therefore do not require an additional to complete primary immunisation.

What if a person becomes immunocompromised after receiving their booster dose. Do they then need an additional dose as well?

No. Individuals with immune-compromise at the time of primary COVID-19 vaccination may have a sub-optimal response to the vaccine. They are recommended an additional dose to enhance their response to the primary vaccination course. It is person’s condition at the time that they receive the primary vaccination course that determines whether or not they need an additional dose.

The immunocompromising conditions associated with a suboptimal response to the primary vaccination course are shaded in blue in Table 5a.2 of the Immunisation Guidelines

Can the additional primary dose be given at the same time as the seasonal flu vaccine or other vaccines?

Yes. The additional dose may be given at the same time or at any interval before or after seasonal influenza vaccine (or any other vaccines). If the additional primary dose is given at the same time, the vaccines should be administered in different arms.

For children aged 5 to 11 years

The National Immunisation Advisory Committee says that a gap is needed between getting COVID-19 vaccines and other vaccines. They recommend a 14 day gap. This recommendation is in place until there is more evidence about co-administration

What if an additional dose of an mRNA vaccine for immunocompromised people is given before the minimum interval? Is there a need to repeat the dose?

If the vaccine is given before the recommended interval (2 months), there is no evidence as to the safety and efficacy of giving a further dose under these circumstances to complete the primary course. The dose should not be repeated. However, a booster vaccine should still be given at the recommended interval (at least 6 months if aged 12-15, and at least 3 months if aged 16 years and older).

The person (and their parents/guardians if less than 16 years old) should be advised regarding the error and the incident reported. The error should be reported to the HPRA.

NIAC recommendation in relation to the waiting time after booster COVID-19 vaccination

The National Immunisation Advisory Committee (NIAC) has suspended the 15-minute wait time after vaccination for those who are receiving a booster covid vaccine only.  This is because the risk of anaphylaxis is extremely rare (1-10 per million) after an mRNA vaccine.

However, those attending for Primary Covid vaccination should continue to wait for 15 minutes.

Those with a history of anaphylaxis from any cause will still need to wait 30 minutes after vaccination.


Additional Resouces

This page was added on 16 March 2022