Vaccine Schedule: Special Populations

Vaccine Schedule: Special Populations

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Cancer patients

People being treated for cancer often have weakened immunity. The changes to the experienced immune system can result from either the cancer itself or the therapy used to treat it, such as chemotherapy or radiation. As a result, people with cancer may be at increased risk of developing infectious diseases or complications if infected. Vaccine needs are also unique for some of these patients.

Get more info about infectious diseases and vaccines for people with cancer.

Pregnant women

When a woman is pregnant her body changes in ways that change her susceptibility to disease. This happens for a couple of reasons:

  • Suppressed immune system function – Since the fetus is not an immunologic match, immune system responses are somewhat suppressed to protect the fetus.
  • Physical changes – Throughout pregnancy, a woman’s body fluid volume increases, putting extra stress on her heart and lungs. This increases her risk for some infections, like influenza and COVID-19, as compared to non-pregnant women of the same age.

Pregnant women are recommended to get vaccines during pregnancy for two reasons — to protect themselves or to protect their babies. 

Because influenza and COVID-19 infections during pregnancy can be more severe compared with those experienced by non-pregnant people of the same age, these two vaccines should be received during pregnancy:

  • Influenza vaccine — Pregnant people are more likely to be hospitalized if infected with influenza. Therefore, the influenza vaccine protects both mom and baby. The shot version should be used.
  • COVID-19 vaccine — Pregnant women should receive the COVID-19 vaccine if they have not already had it since pregnancy increases the risk of experiencing severe COVID-19 disease. Evidence suggests that babies of immunized individuals are also better protected in the months after birth before they can get vaccinated themselves.

Because babies are at greater risk for a few diseases before they can become immune from their own vaccinations, these two vaccines may be recommended during pregnancy: 

  • Tdap vaccine — The Tdap vaccine is recommended during every pregnancy, between 27 and 36 weeks of gestation, to protect the baby from pertussis in the first few months of life before vaccination.
  • Respiratory syncytial virus (RSV) vaccine — The RSV vaccine may be recommended between 32 and 36 weeks of gestation during RSV season to prevent lower respiratory tract infection in infants who will be born during the season. Two points are important. First, an alternative to this vaccination during pregnancy is available for babies. They can get an immunization right after birth if they are born during RSV season. Second, this vaccine is currently only given once, so previously vaccinated women shouldn’t get it during future pregnancies. In this case, their babies can be protected with the immunization given right after birth, depending on when they are born compared with RSV season.

Pregnant women should also avoid certain vaccines during pregnancy:

Resources

Preterm infants

A baby born before 37 weeks is considered preterm. Vaccines are particularly important for preterm babies for a couple of reasons:

  1. Less time for their own immune system to develop — Early immune system cells, called hematopoietic progenitor cells, specialize later during pregnancy. Babies born early tend to have more progenitor cells that have not had the chance to specialize before the early birth.
  2. Less protection provided by maternal antibodies — While antibodies begin to cross the placenta around 13 weeks of gestation, most cross during the third trimester. As a result, a baby born early may have lower levels of maternal antibodies.

Find info about vaccine considerations for preterm babies.

Travelers

  • If you are traveling abroad, it is important to take into consideration any potential health risks at your destination. We recommend consulting a travel clinic.
  • Reasons to consult a travel clinic:
    • They will have the most up-to-date information about the current situation in different areas of the world.
    • Some vaccinations are only needed when participating in specific activities or visiting certain areas of a country or region.
    • In addition to vaccine needs, travel experts can provide other information, such as ways to stay healthy before and during travel as well as what to watch for during and after travel should you be exposed to a potential infection.
  • Considerations when scheduling a visit:
    • Some vaccines require multiple doses and need time to be effective, so plan your trip to the clinic as early as possible.
    • Some areas of the U.S. do not have travel clinics in close proximity.  Keep this in mind when looking for a clinic.
  • Find more information about these common travel-related diseases:

Get more info about infectious diseases and travel.

Weakened immunity

Weakened immunity can result from diseases or treatment of diseases. Generally, people with weakened immunity rely even more on vaccines to protect them from diseases, but in some cases, they are not able to receive vaccines. Then, they have to rely on those around them for protection.

Reviewed by Paul A. Offit, MD, on Nov. 10, 2025