The Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices voted to retain its current recommendations and patient populations for annual influenza vaccination Feb. 26 at its meeting.
The vote was unanimous, but it belies the desire by some for ACIP to call for vote on whether live-attenuated influenza vaccine (LAIV) should be recommended preferentially over inactivated influenza vaccine (IIV) for healthy children.
"Many of us feel it’s long overdue," said Dr. Jeff Duchin, a member of the ACIP influenza working group. "We have a vaccine that even the CDC has acknowledged on a public Web page is superior in young children. Yet we haven’t made that step to make that recommendation, which does influence a lot of health care providers."
LAIV is recommended preferentially for various age groups in the United Kingdom, Canada, Israel, and Germany, as well as in the states of Oregon and Washington.
Dr. Emmanuel "Chip" Walter
Several studies indicate that LAIV may have advantages over IIV in younger populations, but this is not clear in older populations, said influenza work group member Dr. Lisa Grohskopf of the influenza division in the CDC National Center for Immunization and Respiratory Diseases (NCIRD). The work group also struggled with the lower age limit for children when evaluating the efficacy and safety evidence because LAIV is not licensed for children under 2 years of age.
Based on review of the efficacy data, LAIV was associated with a decreased risk of lab-confirmed influenza among 2- to 8-year-olds based on high-quality randomized evidence, but it showed no difference over IIV among 9- to 18-year-olds based on very-low-quality observational data, Dr. Grohskopf said. Among 2- to 8-year-olds, LAIV also was associated with a decreased risk of otitis media, but there was no difference between vaccines with regard to hospitalization, medically attended acute respiratory illness, or influenzalike illness.
As ACIP goes forward, it will need to "harmonize" any possible changes to its recommendations with the American Academy of Pediatrics, which doesn’t meet on the issue until April, Dr. Grohskopf said. It also will have to consider the LAIV supply and the safety of quadrivalent vaccines since all of the studies in the evidence review were done when only trivalent vaccines were available.
Four new, recently licensed vaccines are now available for the 2013-1014 flu season, including FluMist Quadrivalent nasal LAIV (LAIV4) from MedImmune for persons aged 2-49 years; Fluarix Quadrivalent inactivated influenza vaccine (IIV4) from GlaxoSmithKline for those 3 years and older; Flucelvax, a cell culture–based inactivated influenza vaccine (ccIIV3) from Novartis for patients aged 18 years and older; and Flublok, a recombinant hemagglutinin vaccine (RIV3) from Protein Sciences for adults aged 18-49 years.
No new safety concerns have been detected for LAIV4, IIV4, or IIV3 vaccines during the 2013-14 influenza season in patients less than 18 years of age based on interim Vaccine Adverse Event Reporting System surveillance data and Vaccine Safety Datalink data, said Dr. Maria Cano of the CDC National Center for Emerging and Infectious Zoonotic Diseases. Uptake has been limited for the IIV4, cell culture–based IIV3, and recombinant IIV3 vaccines, compared with 194,080 LAIV4 doses and 3.1 million IIV3 doses.
The influenza work group also assessed influenza vaccine safety data in children aged 2-8 years and found no evidence for an increased risk of serious adverse events or medically attended wheezing after LAIV vs. trivalent influenza vaccine (TIV), reported Dr. Emmanuel Walter, director of the Duke Translational Medicine Institute’s clinical vaccine unit at Duke University Medical Center, Durham, N.C. There was evidence for a transient increased risk of mild fever after LAIV vs. TIV, but it was seen only in one study during a single influenza season.
In a pooled safety analysis of LAIV vs. IIV in healthy children, there was no difference between vaccines in medically attended wheezing, fever, or vaccine-related serious adverse events, Dr. Grohskopf said. Both she and Dr. Walter observed that the analyses were limited by several factors, including few studies directly comparing LAIV and IIV, lack of standardized outcome definitions across studies, and difficulty judging the risk of serious rare adverse events.
This led some in attendance to call for additional data on adverse events like seizures at the June meeting, while others tasked the work group with clarifying and separating contraindications from precautions before opening up use of the LAIV to a wider population.
Dr. Walter reported previously serving as a clinical investigator within the last 12 months for GlaxoSmithKline, Merck, and Pfizer and as a data monitoring board member and consultant for Novartis. No other presenters reported having financial disclosures.