Frequently Asked Questions for vaccinators and health professionals

Extended COVID-19 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 aged 12 years and older 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 it 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 additonal primary dose regardless of the vaccine recived 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 the 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 profile 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 additional primary dose in immunocompromised people who have had laboratory-conformed breakthrough infection since they completed their COVID-19 vaccination course?

The additional primary dose should be delayed for at least six months after the laboratory-conformed COVID-19 infection was diagnosed. Serological testing prior to giving a dose is not recommended. If it I not possible to establish if breakthrough COVID-19 infection occurred within this timeframe, the individual 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. Prior to vaccination, they should have been counselled by their obstetric care giver about their individual risk for infection and severe disease and the benefits and risks of vaccination.

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 have not yet made a recommendation that those with immunocompromise will require a further booster dose of COVID-19 vaccine.

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.

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

Yes. The additional primary 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.

Additional Resouces

This page was added on 2 December 2021