Photo by Bill Branson
Child with leukemia
Vaccination may fail to protect young leukemia patients from developing influenza during cancer treatment, according to research published in the Journal of Pediatrics.
Researchers found that young patients with acute leukemia who received flu shots were just as likely as their unvaccinated peers to develop the flu.
The team said these results are preliminary, but they suggest a need for more research and additional efforts to prevent flu in young patients with leukemia.
“The annual flu shot, whose side effects are generally mild and short-lived, is still recommended for patients with acute leukemia who are being treated for their disease,” said study author Elisabeth Adderson, MD, of St. Jude Children’s Research Hospital in Memphis, Tennessee.
“However, the results do highlight the need for additional research in this area and for us to redouble our efforts to protect our patients through other means.”
In this retrospective study, Dr Adderson and her colleagues looked at rates of flu infection during 3 successive flu seasons (2010-2013) in 498 patients treated for acute leukemia at St. Jude.
The patients’ median age was 6 years (range, 1-21). Most patients had acute lymphoblastic leukemia (ALL, 94%), though some had acute myeloid leukemia (4.8%) or mixed-lineage leukemia (1.2%).
Most patients (n=354) received flu shots, including 98 patients who received booster doses. The remaining 144 patients were not vaccinated.
The vaccinated patients received the trivalent vaccine, which is designed to protect against 3 flu strains predicted to be in wide circulation during a particular flu season. The vaccine was a fairly good match for circulating flu viruses during the flu seasons included in this analysis.
Demographic characteristic were largely similar between vaccinated and unvaccinated patients. The exceptions were that more vaccinated patients had ALL (95.5% vs 90.3%; P=0.034) and vaccinated patients were more likely to be in a low-intensity phase of cancer therapy (90.7% vs 73.6%, P<0.0001).
Results
There were no significant differences between vaccinated and unvaccinated patients when it came to flu rates or rates of flu-like illnesses.
There were 37 episodes of flu in vaccinated patients and 16 episodes in unvaccinated patients. The rates (per 1000 patient days) were 0.73 and 0.70, respectively (P=0.874).
There were 123 cases of flu-like illnesses in vaccinated patients and 55 cases in unvaccinated patients. The rates were 2.44 and 2.41, respectively (P=0.932).
Likewise, there was no significant difference in the rates of flu or flu-like illnesses between patients who received 1 dose of flu vaccine and those who received 2 doses.
The flu rates were 0.60 and 1.02, respectively (P=0.107). And the rates of flu-like illnesses were 2.42 and 2.73, respectively (P=0.529).
Dr Adderson said additional research is needed to determine if a subset of young leukemia patients may benefit from vaccination.
She added that patients at risk of flu should practice good hand hygiene and avoid crowds during the flu season. Patients may also benefit from “cocooning,” a process that focuses on getting family members, healthcare providers, and others in close contact with at-risk patients vaccinated.
