Immunity on Immunotherapy — Is It High, Low or Both?

Call the CION helpline now, or go to the nearest emergency room, if there is a fever of 100.4°F (38°C) or higher, new breathlessness, chest pain, confusion, a collapse, or loose motions that keep increasing. On immunotherapy these are assessed the same hour — whether the cause turns out to be infection or an immune reaction.

No. Checkpoint-inhibitor immunotherapy does not suppress your immune system the way chemotherapy does. It releases a brake on immune cells so they can recognise cancer cells. Your white blood cell count is not expected to fall because of it. The risk with this treatment runs the other way — an immune system that becomes over-active.

This is the single biggest source of confusion for families, and it comes from chemotherapy. Chemotherapy kills fast-dividing cells. Bone marrow, where white blood cells are made, divides fast. That is why chemotherapy drops the counts and why everyone has heard the infection precautions that go with it. Immunotherapy does not act on the bone marrow at all.

So both of the things you have been told can be true at once. Your immunity is not low. And you can still become seriously unwell — because an activated immune system can inflame healthy organs such as the bowel, the lungs, the thyroid or the liver. NCCN and ASCO guidance on immune-related adverse events is built around that second risk, not around low counts.

There is one genuine exception, and it changes everything for as long as it lasts: steroids. That is covered in full further down this page.

Chemotherapy lowers your white blood cell count, and with it your resistance to infection. Immunotherapy does not. The table below sets the two side by side and adds the third column most families actually need — what changes once steroids are started for a side effect.

These are the typical patterns described in NCCN and ASCO guidance, not a rule for your case. Note the overlap: many patients receive immunotherapy together with chemotherapy in the same regimen. If that is you, the chemotherapy column applies to you as well — ask your team which columns you are living in.

Usually not from the immunotherapy itself. Given alone, it does not raise infection risk in most patients. What does raise it is everything sitting alongside it — chemotherapy in the same regimen, steroids for a side effect, a port or central line, the cancer itself, and poor nutrition. Your risk is the sum of those.

• Chemotherapy given with the immunotherapy — many regimens combine the two. The low-count window, and the precautions around it, come from the chemotherapy part.
• Steroids started for an immune side effect — the single most important reason immunity actually drops during this treatment.
• Other immune-damping medicines — occasionally added when steroids alone do not control a reaction. These lower defences further.
• The cancer itself — some cancers, and disease in certain sites, reduce resistance regardless of what treatment is being given.
• A port or central line — any line into a vein is a route for bacteria. Redness, pain or discharge at the site is reported the same day, never watched.
• Poor nutrition and uncontrolled diabetes — both reduce resistance independently, and steroids push blood sugar higher while they are being taken.

Ask your oncology team directly which of these apply to you today. The list changes over the course of treatment, and so does the answer to how careful you need to be.

Steroids do lower immunity — that is exactly what they are for. They are the standard treatment for a significant immune-related side effect, and they work by damping down the same immune activity immunotherapy switched on. A short low-dose course changes little. A moderate-to-high dose continued for several weeks genuinely suppresses immunity.

This is the honest answer to "is my immunity high or low". On immunotherapy alone it is neither low nor fragile. On a steroid course for a side effect it is lower, sometimes considerably, and it stays lower until the dose has been reduced and stopped. Ask your team plainly which of those two situations you are in this week — the answer changes what you do at home.

The dose and duration that count as genuinely suppressive are a clinical judgement made by your treating team, following NCCN and ASCO irAE guidance — not a number you can look up and apply yourself. Ask at every visit whether your current dose still counts, because the answer changes as the dose comes down.

Keep it simple. Ordinary sensible hygiene on immunotherapy alone, tighter precautions while on a steroid course, and a thermometer at home either way. Check your temperature whenever you feel unwell. Clear every vaccine with your oncology team before taking it. Tell every doctor you meet that you are on immunotherapy.

1. 1

   Keep a thermometer and record the number

   Write down the reading and the time. "He felt hot last night" and "38.2°C at 9 pm, again at 1 am" lead to two completely different phone calls.

2. 2

   Clear every vaccine with your oncology team first

   Live vaccines — the ones made from a weakened but still living organism — are avoided during immunotherapy and during steroid treatment. Non-live vaccines are usually acceptable, but the timing is decided by your team. Do not accept one at a camp, a pharmacy, a school drive or a travel clinic without asking.

3. 3

   Carry something that says you are on immunotherapy

   A card in the wallet or a note on the phone lock screen. If you reach a casualty at 2 am, that one line changes how quickly the team there acts.

4. 4

   Handle food and water sensibly, and more strictly on steroids

   Freshly cooked hot food, boiled or sealed water, fruit you peel yourself. On immunotherapy alone this is ordinary caution. During a steroid course it matters considerably more.

5. 5

   Do not shrink your life more than the treatment requires

   On immunotherapy alone there is no medical reason to stop working, refuse all visitors or isolate at home. Crowds, travel and gatherings need real thought during a steroid course — not during every cycle of every month.

6. 6

   Tell every doctor, dentist and casualty officer

   Including for something unrelated. Immunotherapy changes how a fever, a rash or breathlessness is interpreted, and it can change which medicines are safe to give you.

Nothing on this list replaces a call to your treating team. If a symptom on the red-flag list at the top of this page appears, act on that list first.

Immunity is the question sitting underneath almost every everyday decision on this treatment — vaccines, crowds, travel, outside food. Each of those has its own answer, and in most cases it is far less restrictive than families expect.

• Can You Take Vaccines During Immunotherapy? — which vaccines are avoided, which are usually fine, and how the timing is decided around your cycles.
• Crowds, Travel and Public Places on Immunotherapy — what genuinely needs avoiding, and what has become a habit for no medical reason.
• Food Safety on Immunotherapy: Is Outside Food Allowed? — the practical version of the food rules, including how they tighten on steroids.
• Immunotherapy at CION Cancer Clinics — how immunotherapy is given as day care, and how patients are monitored for immune-related reactions from the first infusion onward.

Knowing What Your Immunity Is Actually Doing Makes the Precautions Simpler

Patients on immunotherapy at CION are counselled on infection risk and vaccination before the first infusion.