LAIV Safe in Children With Underlying Medical Conditions

The live attenuated influenza vaccine (LAIV) given in the United States appears to be safe in children older than age 2 years who may not currently receive the vaccine due to underlying medical conditions, according to a hospitalization study recently reported online in Vaccine.¹

Alexander Millman, MD, and his colleagues at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, reported that precautions and warnings against the use of the LAIV in children age 2 to 18 years with underlying medical conditions were the result of inadequate safety data and not any specific findings in this population.

The initial safely evaluations were conducted for the approval of the LAIV in healthy children and adults age 5 to 49 years in 2003, with approval extended to include healthy children from 2 to 4 years of age in 2007.^2-6 Since that time, however, no additional safety studies have been conducted to examine the risks in children with underlying medical conditions at the time of vaccination.

The CDC investigation explored this knowledge gap by evaluating cases from claims databases from 2010 to 2012 of hospitalizations among children aged 2 to 18 years who had received the LAIV within 14 days of admission. From a total claims cohort of 1,216,123 children inoculated, 99,208 (8.2%) were documented with an underlying medical condition that did not involve asthma or immunocompromising illnesses. Of these, 642 hospitalizations were recorded in 634 eligible children.

The investigators found no real differences in all-cause hospitalizations in children with nonasthmatic, nonimmunocompromising conditions compared with healthy children in the first window of 1 to 7 days post-vaccination incidence ratio rates (IRRs) 1.1 (95% CI; 0.6 to 2.0, P =.83) vs 0.9 (95% CI; 0.8 to 1.2, P =.60), respectively, or the second window of 8 to 14 days IRRs 0.9 (95% CI; 0.4 to 1.7, P =.67) vs 1.1 (95% CI; 0.9 to 1.3, P =.53), respectively.

Analyses of secondary outcomes specific to respiratory, neurologic, gastrointestinal, constitutional, and head-and-neck events also showed no significant differences in IRRs in children with underlying medical conditions compared with healthy children given LAIV.

Dr Millman reported that this study supports “growing evidence for a favorable safety profile of LAIV in children with non-asthma, non-immunocompromising underlying medical conditions,” although, he said, “We are unable to predict if physicians will change practice behaviors based on these results.  We know that influenza vaccination is safe and that the best way to prevent influenza-associated morbidity and mortality is to ensure that all children aged ≥6 months without contraindications receive an annual influenza vaccination.”

Dr Millman did not comment on whether or not deliberations regarding new Advisory Committee on Immunization Practices (ACIP) guidelines are underway, referring instead to current recommendations by the ACIP available at: https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html.⁶

References

1. Millman AJ, Reynolds S, Duffy J, et al. Hospitalizations within 14 days of vaccination among pediatric recipients of the live attenuated influenza vaccine, United States 2010–2012. Vaccine. 2017;35:529-535. doi: 10.1016/j.vaccine.2016.12.033
2. Bergen R, Black S, Shinefield H, et al. Safety of cold-adapted live attenuated influenza vaccine in a large cohort of children and adolescents. Pediatr Infect Dis J. 2004;23:138-44.
3. Belshe RB, Edwards KM, Vesikari T, et al; CAIV-T Comparative Efficacy Study Group. Live attenuated versus inactivated influenza vaccine in infants and young children. N Engl J Med. 2007;356:685-696. doi: 10.1056/NEJMoa065368
4. Belshe RB, Mendelman PM, Treanor J, et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children. N Engl J Med. 1998;338:1405-1412. doi: 10.1056/NEJM199805143382002
5. Piedra PA, Gaglani MJ, Riggs M, et al. Live attenuated influenza vaccine, trivalent, is safe in healthy children 18 months to4 years, 5 to 9 years, and 10 to 18 years of age in a community-based, nonrandomized, open-label trial. Pediatrics. 2005;116:e397-e407. doi: 10.1542/peds.2004-2258
6. Grohskopf LA, Sokolow LZ, Olsen SJ, et al. Prevention and Control of Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices, United States, 2015–16 Influenza Season. MMWR Morb Mortal Wkly Rep. 2015;64:818-825.