The Covid-19 Pfizer-BioNTech vaccine is safe for people with compromised immune systems or who have had reactions to vaccines in the past.
Any confusion about this may stem from the fact that live vaccines, such as those for measles, mumps, rubella (MMR), cannot be given to some people with weakened immune systems or people who are pregnant.
The Pfizer Covid-19 vaccine is not a live vaccine – meaning it does not contain any of the virus and is therefore safe for almost everyone.
This includes people who are pregnant or breastfeeding, have pre-existing health conditions, or are on treatments that weaken the immune system, such as medicines for cancer and HIV.
It also means people who have had severe reactions to other vaccines or multiple drugs can be safely protected.
Early advice in the United Kingdom Covid-19 vaccine rollout recommended that people with a past history of anaphylaxis should wait, but after careful monitoring it became clear a history of anaphylaxis was not a risk factor, and that position was revised.
Out of an abundance of caution, this group is still asked to wait 30 minutes after vaccination instead of the standard 15 minutes.
The strong safety profile means only a handful of eligible New Zealanders – fewer than 100 – cannot receive the Pfizer Covid-19 vaccine, Professor Nikki Turner, director of the Immunisation Advisory Centre says.
There are only two groups of people who would not be suitable for the vaccine for medical reasons.
The first is a history of anaphylaxis to an ingredient in the vaccine.
“The only major component of the Pfizer vaccine that incredibly rarely can cause anaphylaxis is a product called PEG,” Turner says.
PEG, or polyethylene glycol, also known as macrogol, is a common ingredient in medications, cosmetics, personal hygiene products and processed foods. Allergies to it are rare. It works as a stabiliser in the Pfizer Covid-19 vaccine.
Some people who have reacted to PEG in other things may not have a problem with having it in a vaccine, but should still be assessed by an immunology specialist before vaccination, IMAC says.
The second group is made up of those who have had a severe reaction to the first dose of their Pfizer Covid-19 vaccine. This rare event is why vaccine clinics have adrenaline on hand.
Again, this is confined to a small group – people who have had anaphylaxis immediately after being immunised, or who have had inflammation of the heart – known as myocarditis or pericarditis – as a direct result of the first dose.
IMAC says increasing data now shows many people who have had suspected anaphylaxis after the first dose can be revaccinated safely in a specialist immunology clinic.
For this handful of people who cannot receive Pfizer, the Covid-19 Janssen and AstraZeneca vaccines do not contain PEG. Both of these have been approved by Medsafe but so far no decisions have been made on their use in Aotearoa.
Reporting disclosure statement: Dr Nikki Turner, the medical director of the Immunisation Advisory Centre, provided expert advice for this post. It was reviewed by The Whole Truth: Covid-19 Vaccination expert panel member Dr Dianne Sika-Paotonu, an immunologist and senior lecturer in pathology and molecular medicine at Otago University.
