Vaccination During Chemotherapy: — What Is Safe?

The injected flu vaccine is safe to have during chemotherapy because it is inactivated. When in your cycle you have it matters: white cell counts are at their lowest in the days immediately after treatment, so your team will usually suggest a point when counts are more stable. Raise it at your next appointment so they can plan the timing. Do not use the nasal spray flu vaccine — that version is live and is not safe.

MMR is a live vaccine, and a recently vaccinated child can shed small amounts of the live virus for a short period afterwards. Most international guidance does not recommend withholding childhood MMR vaccination because a parent is on chemotherapy, and the household risk is generally low. Your oncologist can advise on any precautions specific to your situation. This is worth discussing before the child's appointment rather than after.

The inactivated and mRNA COVID-19 vaccines are not live vaccines, and guidance from bodies including ESMO has generally supported their use during cancer treatment. Your immune response may be reduced — meaning the vaccine may protect less well — but it will not cause infection. Confirm the formulation and timing with your oncologist, as advice can vary depending on your specific treatment.

Tell your oncologist as soon as possible. The concern is whether the live organism from the vaccine is still active in your body at the point when your immunity becomes suppressed. Your team will decide whether the treatment schedule needs to be adjusted and what to watch for. Do not assume it does not matter — this is exactly the kind of information your oncologist needs before your first dose.

Tell the travel clinic you are on chemotherapy before any vaccine is discussed. Some travel vaccines are live — yellow fever in particular is mandatory for entry to several countries and is contraindicated during chemotherapy. The travel clinic and your oncologist need to communicate so that your vaccination plan is safe. Some destinations also carry infection risks during active treatment that are worth discussing with your oncologist before booking.

There is no single answer that applies to everyone. Immune recovery after chemotherapy depends on the drugs used, the length of treatment, and individual factors. Most guidance recommends waiting for a defined period after treatment ends and until markers of immune recovery are confirmed — but the timeline is specific to your regimen. Do not assume your immunity has recovered simply because you feel well. Ask your oncologist directly at your follow-up review.

It may work less well than in someone with a healthy immune system, but even a reduced response offers some protection against serious infections like influenza and pneumococcal disease. Timing within your treatment cycle can improve the response, which is why your team may recommend a specific point for certain vaccines. Keeping household members up to date with their own vaccines also reduces the chance of infections reaching you.

The pneumococcal vaccine is inactivated and safe during chemotherapy. People with cancer are at higher risk of serious infection from Streptococcus pneumoniae, which is why it is often recommended proactively. If you were advised to have it before a procedure or before treatment begins, mention it to your oncology team — they will confirm the timing and which formulation is right for you.