- Children with leukemia who were vaccinated against influenza developed flu or flu-like illness
- Flu and flu related complications continue to be the leading cause of death and hospitalization in the U.S
- The overall effectiveness of the vaccine can be reduced due to variance between the vaccine and circulating flu viruses
Children with leukemia who were vaccinated against influenza were found to develop flu during cancer treatment, and further steps need to be taken to protect high-risk individuals, reveals a new study.
The findings from the St. Jude Children's Research Hospital study appears in the Journal of Pediatrics.
The rates of flu infection have been observed in this retrospective study during three successive flu seasons in about 498 St. Jude patients who were being treated for acute leukemia at the hospital.
About 354 patients who received flu shots, including 98 patients who received booster doses, and 144 patients who were not vaccinated were found to have identical rates of confirmed flu and flu-like illness, revealed the research team.
Elisabeth Adderson, M.D., an associate member of the St. Jude Department of Infectious Diseases, lead author of the study said, "This is preliminary data. The annual flu shot, whose side effects are mild and short-lived, is still recommended for patients with acute leukemia who are being treated for their disease."
However, there is a need for further research and to double the efforts of scientists to protect their patients through various means.
Along with good hand hygiene, it is necessary for patients who are at risk to avoid crowds during the flu season, said Adderson.
Patients can also benefit from "cocooning," which is a process of vaccinating family members, health care providers and others who come in close contact with at-risk patients.
In the U.S, flu and other related complications continue to be the leading cause of death and hospitalization.
Children with chronic illness or weakened immune systems are at higher risk for flu complications when compared to healthy children.
High-risk Groups Vaccinated
The American Academy of Pediatrics and the federal Centers for Diseases Control and Prevention Advisory Committee on Immunization recommend an annual vaccination with inactivated flu viruses for those above six months and older.
Extraordinary efforts were taken by the advisory groups to ensure that high-risk groups like pediatric cancer patients, children with chronic illnesses or those with weakened immune responses were all vaccinated.
Children who were being treated for cancer were found to have a weaker immune response to the flu vaccine than those children who were healthy.
In previous studies, about 28 to 100 percent of pediatric cancer patients were found to develop levels of antibodies following vaccination, which provided adequate protection to patients.
When Adderson noticed that flu and flu-like illnesses in patients she knew had been vaccinated, she decided to have a closer look at the effectiveness of the vaccine.
The medical records of St. Jude patients were reviewed by the research team, especially of those who were being treated for acute leukemia during 2011 and 2012, 2012 and 2013 and 2013 and 2014 flu seasons.
Findings of the study
The research team found that there was no significant difference seen in the overall rates of confirmed flu or flu-like illness either in vaccinated or unvaccinated patients during flu seasons or throughout this study.
A booster vaccine dose, which was given to almost 98 (or 19.7 percent of) patients did not reduce the flu or flu-like illness and also it was found that the vaccination did not delay the onset of confirmed flu or flu-like illness.
In this study, patients received the trivalent vaccine, which was designed to protect against three flu strains. These flu strains are predicted to be in full circulation during a particular flu season.
The overall effectiveness of the vaccine can be reduced due to a discrepancy between the vaccine and circulating flu viruses. However, in this study, the flu vaccines were a good match during the flu seasons for circulating flu viruses.
Treating childhood leukemia takes several years and could even leave patients with temporarily weakened immune responses.
The combination can help explain the reduced effectiveness of the vaccine. Further research is required to determine if a subset of pediatric leukemia patients or patients with solid tumors can benefit from this vaccination, said Adderson.