Infection Prevention After a Bone Marrow Transplant

Hematopoietic Cell Transplantation (HCT), more commonly known as bone marrow transplantation, is a procedure used for some patients with cancer, immune disorders, or other genetic diseases. In short, we take stem cells from one person (donor) and give them to a patient (recipient). Those stem cells help repopulate all the blood cells of the body (white blood cells, red blood cells, platelets) and eventually become the patient’s new immune system.

During HCT, there are two major challenges that the patient may face – infection and graft-versus-host disease (GvHD), where the new immune system attacks parts of the patient’s body. Medications are often given to help prevent GvHD. A delicate balance exists after HCT to manage the prevention of both GvHD and infections.

A weak immune system makes a patient more vulnerable to infection and taking away medications early to boost the immune system may help prevent or treat infections, but may also raise the risk of GvHD.

This is why infection prevention is so important – it is one major factor that can be controlled. If we can minimize infections, we can do our best to minimize risks of GvHD; certain medications and vaccinations are important ways to stay healthy after HCT.

Antimicrobial Prophylaxis

Antimicrobial prophylaxis (or sometimes called antibiotic prophylaxis) is when certain medications are given to help prevent infections. Your doctor will consider a lot of factors into deciding which medications to give, including:

• Known prior infections
• Underlying reason for HCT
• Types of medications used during HCT
• Potential infection exposures before or after HCT
• Medication interactions
• Presence of GvHD

Types of antimicrobial prophylaxis include:

• Antibacterial medications – generally, these are not required after HCT to prevent infection. Some exceptions include if the patient has sickle cell disease or chronic GvHD.
• Antiviral medications – to prevent reactivation of either varicella zoster virus (VZV) and/or herpes simplex virus (HSV) and is given if the patient has had infection from these viruses before.
• Antifungal medications – almost all patients will receive an antifungal for infection prevention.
• Pneumocystis pneumonia prophylaxis.
• Passive immunity – a blood product that contains antibodies from blood donors is given frequently after HCT to help prevent bacterial infections.

These medications are continued after HCT for about 6-12 months. Several events that occur after transplant may require these medications to be given longer. Your child’s doctor will help determine how long they are needed after HCT.

Vaccinations

Vaccines are one of the most important ways to stay healthy. After HCT, the patient’s new immune system needs to be retrained to fight vaccine-preventable illnesses such as pertussis (whooping cough), varicella (chickenpox) and measles.

Several factors impact when vaccines can be given to the patient. Some of these include:

• The age of the patient after HCT
• Types of medications used during and after HCT
• The presence of GvHD

In general:

• Revaccination generally starts around four months after HCT, beginning with non-live vaccines
• Vaccines are given on an accelerated schedule
• Live vaccines are given approximately two years after completing HCT
• Vaccine responses are checked on completion, and additional vaccine doses may be necessary

All age-appropriate vaccines should be given as soon as possible; this includes seasonal influenza vaccinations.

Vaccinating the patient is very important, but it is also important for their close contacts (ex. household members) to be current on vaccines. All household members should receive all age-appropriate vaccinations, with the following exceptions:

• Oral polio virus vaccine, live-attenuated influenza vaccine (Flu Mist), and Smallpox vaccine
• Rotavirus vaccination is okay to be given to infants within the household, though the patient should not change diapers and avoid contact with the infant’s feces

As good as antimicrobial prophylaxis and vaccines are, they don’t prevent all illnesses. In addition to “Antimicrobial Prophylaxis and Vaccines,” we discuss ways of “Safe Living” to help prevent infection. To learn more about it, click here.

These steps for infection prevention are some of the most important things you can do to help keep your child safe and healthy after a bone marrow transplant. For more information about the Host Defense Program at Nationwide Children's Hospital, click here.