Who Cannot Have the Yellow Fever Vaccine?

The yellow fever vaccine protects almost everyone who needs it, for life, from a single dose. But it contains a live, weakened form of the virus, and it has real contraindications. If you have been told you might not be able to have it — or you are over 60, pregnant, or taking medicines that affect your immune system — this guide explains what the rules actually say and what your options are.

It forms part of our complete guide to the yellow fever vaccine in Hampshire.

Why this vaccine has stricter rules than most

Because the vaccine is live, the immune system has to control a weakened virus. For most people that is exactly why it works so well — one dose, immunity in 95 to 100 per cent of recipients, protection for decades. But in a small number of people whose immune systems cannot manage even a weakened virus, it can cause serious illness.

After the Commission on Human Medicines reviewed serious and fatal reactions to the vaccine, UK guidance began requiring a standardised pre-vaccination checklist for every patient. That checklist is how the small number of people at real risk get identified before they are vaccinated, which is why we go through your history in detail rather than taking it as read.

Who is never vaccinated

NaTHNaC guidance states the vaccine should not be given under any circumstances to:

• Infants under six months old.
• Anyone with a confirmed anaphylactic reaction to a previous dose, or to any component of the vaccine.
• Anyone with a thymus disorder — including myasthenia gravis and thymoma — or who has had the thymus gland removed for any reason, including incidentally during heart surgery. This is why we ask about cardiac operations that may seem unrelated.
• Anyone with a primary or acquired immunodeficiency, including symptomatic HIV infection, or asymptomatic HIV where there is evidence of impaired immune function.
• Anyone immunosuppressed by treatment — high-dose systemic steroids, immunosuppressive biologic therapy, radiotherapy or cytotoxic drugs.
• Anyone with a close blood relative — parent, full sibling or child — who had a serious neurological or organ reaction to the vaccine that was not explained by a known risk factor, in case of an unidentified genetic predisposition.
• Travellers aged 60 or over going only to areas classed as low potential for exposure.

If any of these applies to you, a designated centre should not vaccinate you. The conversation then turns to your route, whether it can be adjusted, and whether an exemption letter is appropriate.

Who needs individual assessment

These groups sit in the “precautions” category. Vaccination may still be appropriate where travel to a risk area is unavoidable, but only after a careful assessment weighing the real risk of the disease against the higher risk of a reaction.

Aged 60 and over

Serious reactions become more likely with age, which is why UK guidance says the vaccine should only be given to over-60s where there is a significant and unavoidable risk of catching yellow fever — a genuine risk destination, not a low-potential one.

In practice: a 64-year-old heading into Kenya’s risk areas is usually vaccinated after assessment. The same traveller visiting only Tanzania is not, because Tanzania is classed as low potential for exposure.

Pregnancy and breastfeeding

Live vaccines are avoided in pregnancy as a principle, but where travel to a risk area cannot be avoided, vaccination may be considered following individual risk assessment. Often the better answer is to change the timing or the destination, and we will say so if that is our honest view.

Infants aged six to eight months

Vaccinated only in exceptional circumstances, on specialist advice. From nine months the vaccine is routine where needed.

Living with HIV

Well-controlled HIV — a CD4 count above 200 with a suppressed viral load — is a precaution rather than an absolute bar, and vaccination may proceed after assessment, sometimes with specialist input. Symptomatic HIV, or evidence of impaired immune function, is an absolute contraindication.

Steroids and immune-modulating medicines

High-dose steroids and biologic therapies are contraindications. Low-dose steroids and non-biological oral immune-modulating drugs sit in the precaution group. Please bring a full list of everything you take — including creams, inhalers, injections and infusions, and the dates of any recent courses.

Currently unwell

If you have a fever or are acutely unwell, vaccination is postponed until you have fully recovered.

Egg allergy

The vaccine is produced using chick embryos, so a confirmed anaphylactic reaction to egg is a contraindication. Milder egg allergy is not automatically a bar — it needs assessing individually, so tell us the details of what happens when you eat egg rather than assuming either way.

The Medical Letter of Exemption

If vaccination is ruled out but your destination demands a certificate, a designated centre can issue a Medical Letter of Exemption after assessing you. It documents that vaccination is contraindicated on medical grounds, and receiving countries are asked to take it into consideration.

There is also a less obvious scenario: sometimes there is no absolute contraindication, but after assessment the risk of a vaccine reaction is judged greater than the risk of the disease. An exemption letter can be an option there too.

Be clear-eyed about what it is, though. Acceptance is at the destination country’s discretion, and the letter offers no protection against the disease itself. An exempt traveller in a risk area depends entirely on meticulous mosquito bite avoidance — repellent, covered skin, treated nets, and awareness that these mosquitoes bite during the day.

Frequently asked questions

Can I have the yellow fever vaccine if I’m over 60?
Often yes, where your destination carries genuine risk, after individual assessment. If you are travelling only to a low-potential area, it is not given.

I’m allergic to eggs — is it ruled out?
Confirmed anaphylaxis to egg is a contraindication. Milder allergy needs individual assessment, so tell us exactly what happens.

I had heart surgery years ago — why do you ask about my thymus?
Because the thymus is sometimes removed incidentally during cardiac surgery, and thymus removal for any reason is an absolute contraindication. Many people do not know it happened.

I’m on methotrexate, a biologic, or recent chemotherapy — can I be vaccinated?
Biologics, high-dose steroids, chemotherapy and radiotherapy are contraindications. Some non-biological oral immune modulators are precautions, assessed individually.

Can my baby have it?
Not under six months. Six to eight months only in exceptional circumstances on specialist advice. From nine months it is routine where needed.

I’m pregnant and my trip can’t move — what are my options?
Vaccination may be considered after risk assessment where travel is unavoidable, but changing timing or destination is often the better option. We will talk it through honestly.

Who decides for my trip?
A GPhC-registered pharmacist at our designated centre, using the required pre-vaccination checklist, your medical history and your specific itinerary.

General information for UK travellers, checked against NaTHNaC/TravelHealthPro guidance. Suitability for this vaccine is always an individual, face-to-face clinical decision. If you are unsure about your medicines or medical history, bring the details to your appointment.