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Children 6 months of age or older, who have never received a flu vaccine before, are recommended to receive a priming vaccine and a booster – one month apart – the first time.
For children over the age of 6 months, the TIV flu shot may be used, and for healthy children 24 months or older, the LAIV nasal spray may be substituted.
Until now, a lack of clinical studies have left some doubts as to whether a combination of the TIV flu shot and LAIV nasal vaccine would perform equally as well.
From the NIH today, we’ve a report on clinical trials conducted at Saint Louis University, along with investigators at Vanderbilt University in Nashville, and the Cincinnati Children's Hospital – funded by NIAID -that looks at the immune responses in toddlers who received one of four different flu shot combinations:
- two injections of a TIV vaccine
- two LAIV nasal spray vaccines
- A LAIV nasal spray followed by a TIV shot
- a TIV shot followed by the LAIV nasal spray
The good news . . . particularly for children at least 2 years of age with an aversion to needles . . . is that two sprays of the LAIV vaccine appear to produce the same level of antibody response as two flu shots.
And when a child receives at least one of their vaccines via the LAIV nasal spray, they produced a wider array of immune T cells, which may help protect against other flu strains.
This from NIH News.
Any Prime-Boost Mix of Injected or Spray Flu Vaccine Shields Toddlers
Broadest Immune Response from Nasal Spray Vaccine, NIH-Funded Study Finds
Children younger than 3 years old receive the same protective antibody response from the recommended two doses of licensed seasonal influenza vaccines regardless of whether the two doses are injected by needle, inhaled through a nasal spray or provided through one dose of each in any order, according to researchers funded by the National Institutes of Health. Doctors usually give young children two matching vaccines, and one goal of the study was to determine whether giving two different types of vaccines works just as well.
Daniel Hoft, M.D., Ph.D., conducted a trial of influenza vaccines in young children.
Credit: Saint Louis University
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The researchers found that all four dosing patterns were safe and induced similar levels of protective antibodies. However, when the investigators looked at responses from the T-cell arm of the immune system, a striking difference emerged. They could not detect influenza-specific T cells in children who received only TIV, according to Dr. Hoft. But, he added, “The kids who received at least one dose of LAIV nasal spray vaccine produced significant amounts of three important T-cell subtypes that are likely to confer additional protection beyond that afforded by antibodies alone.”
Previous studies have demonstrated that children are better protected against influenza infection and disease by LAIV than by TIV, Dr. Hoft noted. However, few studies have examined the T-cell responses elicited by LAIV when given to very young children who have little prior natural exposure to seasonal influenza viruses. Distinguishing T-cell responses due to vaccination from those arising after natural exposure to influenza virus becomes more difficult as a child ages, he explained. Because the children in the trial were all younger than 3 years old, the researchers could be confident that spikes in levels of the three T-cell subtypes they detected were likely due to the vaccinations.
Children who received only one dose of LAIV had T-cell responses similar to those who received two, and the order of vaccine types did not make a significant difference in the size of the T-cell response. However, because LAIV has sometimes been associated with increased incidence of wheezing in the youngest recipients, the results of this trial suggest that the best regimen for kids younger than 24 months may be TIV followed by LAIV, Dr. Hoft said. Larger clinical trials are required to confirm the safety and efficacy of such an approach, he added.
The results are published today in the Journal of Infectious Diseases, and the abstract may be read at:
Live and Inactivated Influenza Vaccines Induce Similar Humoral Responses, but Only Live Vaccines Induce Diverse T-Cell Responses in Young Children
Daniel F. Hoft, Elizabeth Babusis, Shewangizaw Worku, Charles T. Spencer, Kathleen Lottenbach, Steven M. Truscott, Getahun Abate, Isaac G. Sakala, Kathryn M. Edwards, C. Buddy Creech, Michael A. Gerber, David I. Bernstein, Frances Newman, Irene Graham, Edwin L. Anderson and Robert B. Belshe
