Alternative measures necessary to protect children with cancer against influenza

Additional steps are necessary to protect children with leukemia against influenza, as these patients were found to be just as likely as unvaccinated children to develop the virus.

“The results reinforce the importance of hand washing and other measures to help protect vulnerable patients from influenza infections,” Elisabeth E. Adderson, MD, associate member of the department of infectious diseases at St. Jude Children’s Research Hospital and University of Tennessee Health Sciences Center, and colleagues wrote.

Adderson and colleagues performed a retrospective review of demographic and clinical characteristics data for 498 patients (median age, 6 years) with acute leukemia who received treatment at a pediatric cancer center during the 2010-2011, 2011-2012 and 2012-2013 influenza seasons.

Overall, 71.1% of patients received the trivalent inactivated inuenza vaccine; of those children, 19.7% received a booster dose of the vaccine.

Researchers observed no differences in the overall rates of influenza or influenza-like illness between vaccinated and unvaccinated patients for any influenza season.

Moreover, no differences were observed in the rates of influenza or influenza-like illness among those who received one dose of trivalent inactivated inuenza vaccine vs. those who received two doses of the vaccine.

“This is a preliminary finding. 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,” Adderson said in a press release. “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.”

HemOnc Today spoke with Adderson about the study and the implications of the findings.

Question: What prompted this research?

Answer: We have known from studies about vaccines in children with cancer that a reasonable number of them appear to have good responses to the vaccine. However, there is very little research into how well it translates practically into protection against infection. When we began noticing numbers of our vaccinated patients that developed influenza, this led us to examine how well the vaccine was working in the population.

Q: How did you conduct the study?

A: We looked at children with acute leukemia and we followed them over three influenza seasons. It was a retrospective study, so we looked back at whether the patients developed influenza or whether they developed an influenza-like illness. Then we compared the number of patients who had the same seasonal influenza vaccine during those years with those who had not been vaccinated.

Q: What were the key results?

A: We found there was really no difference in the number of patients who developed influenza or influenza-like illness based upon their vaccination status. Those who had been vaccinated were just as likely to develop influenza or influenza-like illness as those who were not vaccinated.

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Q: Did your findings surprise you?

A: Yes, a little. Based upon the immunogenicity data and how well it appeared as though the vaccine was working, I would have expected more protection, as in otherwise healthy children. We did not expect to see very little benefit.

Q: What are the clinical implications of the findings?

A: First, this was a single, small, retrospective study, and the findings show we need to conduct further research. We need to perform these studies in a more rigorous way, in higher-risk populations, so that we can be sure our observations are correct. The most important implication is we should not assume that, because a patient has been vaccinated, they are protected against influenza. Instead, we should redouble our efforts to protect them against influenza in other ways and, of course, other respiratory viruses. These efforts can include good handwashing, avoiding crowds during influenza season and cocooning — or vaccinating family members and health care providers to whom the patient is exposed the most.

Q: Do you plan additional research?

A: Yes, we are working on trying to identify what specific immunologic characteristics make it difficult for these children to develop responses to vaccination. We also plan additional clinical studies to confirm our findings.

Q: What is the overall take-home message for oncologists who care for children with leukemia and other cancers?

A: The major take-home message is that we should not rely fully on the influenza vaccine to protect these high-risk patients. We should be sure to use other strategies in combination with the influenza vaccine. – by Jennifer Southall

Reference:

Sykes A, et al. J Pediatr. 2017;doi:10.1016/j.peds.2017.08.071.

For more information:

Elisabeth E. Adderson, MD, can be reached at University of Tennessee Health Sciences Center, 920 Madison Ave., Memphis, TN 38103; email: elisabeth.adderson@stjude.org.

Disclosure: Adderson reports no relevant financial disclosures.