Can Cancer Patients Receive Flu or Pneumonia Vaccines?

One of the questions we hear most often in our clinic every autumn is: “Doctor, I am receiving chemotherapy; can I have a flu vaccine?” The short answer: Yes, most cancer patients can and should receive a flu vaccine. Current guidelines also recommend vaccination against pneumococcus, the bacterium causing pneumonia, for cancer patients receiving immunosuppressive treatment, regardless of age. What matters is receiving the right vaccine at the right time. In this article, before the 2026-2027 flu season, we discuss which vaccines should be given, when and how, in light of current guidelines.

Why does infection risk increase in cancer patients?

The immune system protects us against viruses and bacteria through antibodies and defense cells. In cancer, this defense may weaken for two reasons:

• The disease itself: Blood cancers, particularly leukemia, lymphoma and multiple myeloma, directly affect immune cells. Solid tumors may also send immunosuppressive signals into their surroundings.
• Treatments: Chemotherapy, some targeted treatments, drugs targeting B cells (such as rituximab), high-dose cortisone, stem cell transplantation and CAR-T cell therapy may suppress immunity temporarily or for a long period. We discussed chemotherapy-related low white blood cell counts in our article on neutropenia in detail.

According to the CDC, cancer, particularly leukemia and lymphoma, increases the risk of flu complications. In a large analysis comparing cancer patients hospitalized with flu in the United States with cancer patients hospitalized without flu, pneumonia (18,4% versus 13,2%) and blood poisoning (sepsis; 19,5% versus 9,3%) were more common in patients with flu, and the risk of death in hospital was also higher (5,4% versus 4,2%). We described signs of infection during chemotherapy in this article .

Does the flu vaccine work in cancer patients?

The thought “My immunity is weak, so the vaccine will not work” is common; however, the evidence shows otherwise. Published in 2019 in Journal of Clinical Oncology, a study examined cancer patients in Ontario, Canada, over 2010-2016, covering 6 flu seasons and 26.463 cancer patients. Its results were as follows:

These rates are lower than effectiveness in healthy young people; however, when a risk affects thousands of patients during flu season, a simple and safe vaccine reducing flu and hospitalizations by one-fifth is an important gain. Moreover, vaccination may help make the illness milder even if flu occurs.

Can people receiving immunotherapy be vaccinated?

Yes. There were concerns that vaccination would increase immune-related side effects in patients receiving immunotherapy (immune checkpoint drugs). In an analysis covering 19 studies and 4.705 patients, these side effects did not increase in vaccinated patients (32% versus 41%). Another Canadian study also found no increase in the risk of emergency attendance or hospitalization during the 42 days after vaccination. Vaccine responses are also generally good in patients receiving immunotherapy.

Which flu vaccine?

• Injectable (inactivated) vaccine: This is the correct choice for cancer patients. The vaccine virus is not live, so it does not cause flu.
• Nasal spray vaccine (live): It is not given during cancer treatment.
• Vaccines for the 2026-2027 season: In line with World Health Organization recommendations, all three of the three virus strains in this season’s vaccines have been updated. Because the B/Yamagata lineage has not been detected since 2020, vaccines now have three components (trivalent). In Türkiye, vaccines began reaching pharmacies from mid-September.
• High-dose vaccine: The high-dose flu vaccine is licensed in Türkiye for people aged 60 and over. ASCO recommends the high-dose vaccine for stem cell transplant recipients regardless of age. In a small study of patients receiving chemotherapy who were under 65, the high-dose vaccine produced a stronger antibody response; however, it has not yet been shown that this translates into less flu and fewer hospitalizations. Decide with your oncologist which vaccine is appropriate for you.

When should the vaccine be given?

Timing is one of the most important factors determining vaccine effectiveness. According to ASCO’s 2024 guideline, the general principles are as follows:

• Before treatment if possible: Vaccines produce their best response when the immune system has not yet been suppressed. Therefore, ideally, vaccination should take place 2-4 weeks before cancer treatment starts.
• Also possible during treatment: Nonlive vaccines can be given during or after chemotherapy, immunotherapy, hormone therapy, radiotherapy or surgery. If you are receiving chemotherapy, your oncologist will plan which day in your treatment cycle the vaccine will be given.
• B cell-targeted treatments: Because the vaccine response is very weak after drugs such as rituximab, nonlive vaccines are given at least 6 months after the last dose; subsequent repeat vaccination is recommended in these patients.
• Stem cell transplantation and CAR-T: Vaccination is restarted after transplantation; flu, pneumococcal and COVID-19 vaccines can begin from month 3 at the earliest. For live vaccines, wait at least 2 years.

Because the flu season is generally active between October and March, vaccination in September-October is appropriate; however, vaccination later in the season also provides benefit. For drugs and other measures to prevent infections in cancer patients, you can consult our article on preventive treatments .

Pneumonia (pneumococcal) vaccine

Pneumococcus is one of the most common bacterial causes of pneumonia; it may also cause severe conditions such as bloodstream infection (bacteremia) and meningitis. Because flu may predispose to pneumococcal pneumonia, the two vaccines complement each other.

For whom? Older guidelines recommended pneumococcal vaccination mainly for people over 65. Current recommendations are broader:

• The ASCO 2024 guideline recommends pneumococcal vaccination for adult cancer patients receiving immunosuppressive treatment.
• The CDC recommends pneumococcal vaccination for all adults aged 50 and over and for people aged 19-49 with conditions such as cancer, leukemia and lymphoma or receiving immunosuppressive drugs or radiotherapy.
• The EKMUD 2025 Adult Immunization Guide also recommends vaccination for people aged 50 and over and for risk groups, including immunocompromised people, with a single dose of PCV20.

Which vaccine? There are currently two options: a single dose of PCV20 (20-valent conjugate vaccine), or PCV15 first, followed at least 8 weeks later by PPSV23. For those previously given PCV13 or PPSV23, at least 1 year later a single dose of PCV20 is recommended. Another 21-valent vaccine (PCV21) is approved abroad, but we could not find information about its licensing in Türkiye.

Other important vaccines

Family members and close contacts should also be vaccinated

One of the most effective ways to protect a cancer patient is to vaccinate the people living with and caring for them. ASCO strongly recommends keeping household members’ vaccinations up to date. Family members can generally also receive live vaccines; the sole exception is that those living with stem cell transplant recipients should choose the injectable flu vaccine rather than the nasal spray.

What should you do if flu symptoms occur?

You may get flu even if vaccinated. Do not wait if symptoms such as fever, cough, sore throat, runny nose, headache, chills, weakness and widespread muscle pain occur. Particularly if you are receiving chemotherapy, fever requiring emergency assessment may be a sign of neutropenic fever.

The CDC recommends starting antiviral treatment as soon as possible when flu is suspected in high-risk people such as cancer patients. Treatment is most effective within the first 48 hours after symptoms begin, but also provides benefit after 48 hours in hospitalized or severely ill patients. Treatment may need to last longer in immunocompromised patients.

What to do in practice?

• Ask your oncologist: “What is the best time for me to have flu and pneumonia vaccines this autumn?”
• If treatment is about to start, complete your vaccinations 2-4 weeks beforehand if possible.
• Choose the injectable flu vaccine rather than the nasal spray vaccine.
• Your pneumococcal vaccine should be planned by stating which vaccine you previously received and when.
• Ensure your household members receive a flu vaccine.
• Pay attention to hand hygiene, and consider wearing a mask in crowded, indoor environments during flu season. We explained precautions in cold weather in this article .
• For fever and flu symptoms, call your oncology team without delay.

Frequently asked questions

Can I have a flu vaccine while receiving chemotherapy?

Yes. The injectable, nonlive flu vaccine can also be given during chemotherapy. Your oncologist plans which day of your treatment cycle the vaccine will be given. Ideally, if possible, vaccination should take place 2-4 weeks before treatment begins.

Will the vaccine give me flu?

No. The injectable flu vaccine contains no live virus and does not cause flu. Pain at the injection site, brief weakness or mild fever may occur; these generally resolve within 1-2 days.

My immunity is weak; will the vaccine still work?

Yes, it works, although less effectively than in healthy people. In 26 thousand cancer patients, vaccination reduced laboratory-confirmed flu by 21% and hospitalization due to flu by 20%. In those receiving B cell-targeted drugs such as rituximab, the response may be very weak, so timing is planned separately.

Do I need the pneumonia vaccine every year?

No. The current recommendation is a single dose of PCV20 or PCV15 followed by PPSV23; it is not repeated every year like the flu vaccine. Tell your physician which pneumococcal vaccines you previously received.

I receive immunotherapy; will vaccination increase side effects?

Studies show that the flu vaccine does not increase immune-related side effects in patients receiving immunotherapy. Vaccination is recommended.

My treatment has ended; do I still need vaccination?

Yes. After treatment ends, annual flu vaccination and completion of your other vaccinations are still recommended. You can find all vaccines recommended for adult cancer patients in our article on vaccination recommendations .

Glossary

Influenza

The flu virus. Because its strains change each year, vaccination needs to be repeated annually.

Inactivated vaccine

A nonlive vaccine containing killed virus or virus fragments; it does not cause the disease.

Live vaccine

A vaccine containing a weakened live microorganism. It is not given during cancer treatment because it may cause disease in immunocompromised people.

Pneumococcus

A bacterium that can cause pneumonia, bloodstream infection and meningitis (Streptococcus pneumoniae).

Conjugate vaccine (PCV)

A vaccine type in which the bacterium’s sugar structure is linked to a protein, producing stronger and longer-lasting immunity. PCV20 provides protection against 20 different pneumococcal types.

Neutropenia

A decrease in the white blood cells called neutrophils that fight infections; it is a common effect of chemotherapy.

Vaccine effectiveness

A measure showing the percentage reduction in disease risk in vaccinated people compared with unvaccinated people.