Written by the Caxton Pharmacy team · Checked against NaTHNaC guidance updated 18 February 2026, UKHSA Green Book chapter 35 and MHRA safety advice.
The yellow fever vaccine protects almost everyone who needs it, for life, from a single dose. But it is a live vaccine with real contraindications, and UK rules around it were deliberately strengthened in 2019. If you have been told you might not be able to have it, or you are over 60, pregnant, or on medicines that affect your immune system, this guide explains what the rules actually say and what your options are. It sits alongside our complete yellow fever vaccine guide for Bromley travellers, which covers the disease, countries and certificate in full.
Why this vaccine has stricter rules than most
The vaccine contains a live, weakened strain of the virus. For most people that is precisely 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 handle even a weakened virus, it can cause the very kinds of illness it exists to prevent.
Serious reactions are rare, around one case per 100,000 doses for the neurological form (YEL-AND) and around one per 300,000 for the organ form (YEL-AVD), but they are serious, and the risk rises with age. After two UK fatalities in 2018 and 2019, the MHRA and the Commission on Human Medicines strengthened the precautions, and every UK vaccination now requires a standardised pre-vaccination checklist. The full safety data sits in the side effects section of our main guide.
KEY POINT. The eligibility rules are not red tape. They are the mechanism that keeps serious vaccine reactions at the one-in-hundreds-of-thousands level. A centre that checks carefully is protecting you, not inconveniencing you.
Absolute contraindications: who is never vaccinated
| Group | Why |
|---|---|
| Babies under 6 months | Risk of vaccine-associated encephalitis in young infants |
| Anaphylaxis to a previous dose or any vaccine component (including severe egg allergy) | The vaccine is grown in chick embryos; severe allergic reaction risk |
| Thymus disorder or thymus removal for any reason (including incidentally during heart surgery) | Strongly associated with the most serious vaccine reactions |
| Significant immunosuppression: symptomatic HIV, immunodeficiency, high-dose steroids, biologics, chemotherapy, radiotherapy | A weakened immune system may not control the live vaccine virus |
| First-degree relative (parent, sibling, child) who had YEL-AND or YEL-AVD without a known risk factor | Possible unidentified genetic predisposition |
| Age 60+ travelling only to “low potential for exposure” areas | The vaccine risk outweighs the negligible disease risk |
If any row above applies to you, a designated centre should not vaccinate you, and any clinic that would without asking the questions is a clinic to walk out of. What you need instead is an honest conversation about your route and, where appropriate, an exemption letter, covered below.
Precaution groups: vaccinated only after careful assessment
Aged 60 and over. The risk of serious vaccine reactions roughly triples with age: about 2.2 YEL-AND and 1.2 YEL-AVD cases per 100,000 doses in over-60s, higher again over 70. UK guidance therefore allows vaccination only where there is a significant and unavoidable risk of catching yellow fever, a genuine risk destination rather than a low-potential one. In practice, for a 64-year-old heading into Kenya’s risk areas the vaccine is usually justified; for the same traveller visiting only Tanzania it is not given.
Pregnancy and breastfeeding. Live vaccines are avoided in pregnancy on principle, but where travel to a risk area is unavoidable, vaccination may be considered after a careful risk assessment. The same applies to breastfeeding mothers. Often the better answer is changing the timing or destination of the trip, and we will say so when it is.
Babies aged 6 to 8 months are vaccinated only in exceptional circumstances on specialist advice; from 9 months the vaccine is routine where needed.
Living with HIV. Well-controlled HIV (CD4 count above 200 with a suppressed viral load) is a precaution, not an absolute bar; vaccination may proceed after assessment, sometimes with specialist input. Symptomatic HIV or a low CD4 count is an absolute contraindication.
Steroids and immune-modulating medicines. High-dose steroids and biologic therapies are contraindications. Low-dose steroids and some non-biologic immune modulators sit in the precaution group. Bring a list of everything you take, including creams, inhalers, injections and infusions, and the dates of any recent courses.
KEY POINT — the assessment is the service. Two travellers with the same passport and the same destination can leave with different plans: one vaccinated, one carrying an exemption letter and a bite-avoidance kit. That judgement, made face to face with your medical history in front of us, is what a designated centre is for.
The Medical Letter of Exemption: your paperwork route
If vaccination is ruled out but your destination demands a certificate, a designated centre can issue a Medical Letter of Exemption (MLoE) after assessing you. It documents that vaccination is contraindicated on medical grounds, and border authorities are asked to take it into consideration.
Be clear-eyed about what it is: acceptance is at the destination country’s discretion, and the letter does nothing against the disease itself. An exempt traveller in a risk area relies entirely on rigorous mosquito-bite avoidance, repellent, covered skin, treated nets, day-biting awareness, and for some itineraries the honest advice is to re-route. How exemption letters interact with the certificate system is covered further in our full guide to the yellow fever vaccine and certificate.
Not sure which group you fall into? Book a consultation and bring your medication list; we will work through the checklist with you properly.
Frequently asked questions
Can I have the yellow fever vaccine if I’m over 60?
Often yes, when your destination carries genuine yellow fever risk and travel is unavoidable, after an individual assessment. It is not given to over-60s for low-potential areas such as Tanzania alone.
I’m allergic to eggs. Is the vaccine ruled out?
Only confirmed anaphylactic egg allergy is an absolute contraindication. Milder egg reactions need a careful assessment, and many childhood egg allergies are outgrown. Tell us the full history and we will assess it properly.
I had heart surgery years ago. Why do you ask about my thymus?
Some cardiac operations remove part of the thymus gland incidentally, and any thymus removal, however it happened, is an absolute contraindication to this vaccine. It is one of the most important questions on the checklist.
I’m on methotrexate / a biologic / recent chemotherapy. Can I be vaccinated?
Immunosuppressive biologics, chemotherapy and high-dose steroids are contraindications. Some lower-dose or non-biologic medicines sit in the precaution group instead. Bring the exact names, doses and dates and we will assess, with specialist input where needed.
Can my baby have the vaccine?
From 9 months, yes, where the trip needs it. Babies under 6 months are never vaccinated, and 6 to 8 months only exceptionally on specialist advice. For unavoidable travel with a young baby, bite avoidance and itinerary planning carry the load.
I’m pregnant and my trip can’t move. What are my options?
A careful assessment weighing the destination’s actual risk against the vaccine. Depending on your route, the answer may be vaccination, an exemption letter with strict bite avoidance, or adjusting the itinerary. We will talk it through honestly.
If I can’t be vaccinated, will the exemption letter definitely get me in?
No promise can be made: acceptance is at the destination’s discretion. Most countries respect a properly issued MLoE, but we will never pretend it is a guarantee, and it gives no protection against the disease itself.
Who decides all this for my trip?
A trained clinician at a designated Yellow Fever Vaccination Centre, using the UK’s standardised checklist and your full history. That is exactly what your appointment at Caxton Pharmacy in Bromley involves. Book here or call 020 8460 0377.
General information for UK travellers, checked against NaTHNaC/TravelHealthPro guidance (updated 18 February 2026), UKHSA Green Book chapter 35, and MHRA safety advice. Suitability for this vaccine is always an individual, face-to-face clinical decision.
Sources: NaTHNaC yellow fever factsheet · UKHSA Green Book chapter 35 · MHRA Drug Safety Update (Stamaril)
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