AAP policy emphasizes importance of vaccination after high-severity flu season :

With the 2018-’19 influenza season imminent, the Academy has updated its policy statement Recommendations for Prevention and Control of Influenza in Children, 2018-2019. The policy is available at https://doi.org/10.1542/peds.2018-2367 and will be published in the October issue of Pediatrics.Key points are highlighted below.

The 2017-’18 influenza season was of high severity for all age groups and geographically widespread for an extended period. Influenza A (H3N2) viruses predominated overall for the season. There were high levels of outpatient clinic and emergency department visits for influenza-like illness and a record number of pediatric deaths. Excluding the 2009 pandemic, the number of pediatric deaths (179) was the highest reported since influenza-associated pediatric mortality became a nationally notifiable condition in 2004. Among the 154 children with known medical history, 49% of the deaths occurred in previously healthy children.

The annual influenza vaccine is recommended for everyone 6 months and older as soon as the seasonal influenza vaccine is available. The start of the influenza season is unpredictable, and vaccination remains the best preventive measure against influenza. Immunization should be completed preferably by the end of October. There is no evidence that administering the influenza vaccine early in the season increases the risk of infection for children.

Inactivated influenza vaccine (IIV3/IIV4) is the primary vaccine choice for all children. To vaccinate as many children as possible this influenza season, neither inactivated vaccine formulation (IIV3 or IIV4) is preferred over the other. Vaccination should not be delayed to obtain a specific vaccine product. The influenza A (H3N2) and B (Victoria lineage) strains in the 2018-’19 vaccine have changed from last season.

Quadrivalent live attenuated influenza vaccine (LAIV4) may be used for children who would not otherwise receive a vaccine (e.g., refusal of IIV) and for whom it is appropriate by age (2 years of age and older) and health status (healthy, without any underlying chronic medical condition). The effectiveness of LAIV4 was inferior against A/H1N1 during past seasons and is unknown against A/H1N1 for this upcoming season. Further details can be found at www.aappublications.org/news/2018/06/07/influenza060718. Families should receive counseling on the revised vaccine recommendations for the 2018-’19 season.

 The number of recommended doses of influenza vaccine depends on a child’s age at the time of the first administered dose and vaccine history. Influenza vaccines are not licensed for administration to infants younger than 6 months. Children 6 months through 8 years may need two doses given four weeks apart (see figure). A child who receives only one of the recommended two doses as a quadrivalent formulation is likely to have less protection against the additional B virus. Children 9 years and older need only one dose of influenza vaccine, regardless of which vaccine is used.

Pregnant women may receive IIV at any time during pregnancy. Pregnant women are a population of special concern because they are at increased risk for complications from influenza. Vaccination also provides protection for infants during their first 6 months of life, when they are too young to receive influenza vaccine themselves, through transplacental passage of antibodies. Influenza vaccination is safe during breastfeeding for mothers and their infants.

All health care personnel should receive an annual influenza vaccine to prevent influenza and reduce health care-associated influenza infections. This is a crucial step in preventing influenza because health care personnel often care for individuals at high risk for influenza-related complications.

 Antiviral medications are important in the control of influenza but are not a substitute for influenza vaccination. Pediatricians should promptly identify children suspected of having influenza infection for timely initiation of antiviral treatment, when indicated, to reduce influenza-associated morbidity and mortality. Clinical judgment (on the basis of underlying conditions, disease severity, time since symptom onset and local influenza activity) is an important factor in treatment decisions for pediatric patients who present with influenza-like illness. Antiviral treatment should be started as soon as possible after illness onset and should not be delayed while waiting for a definitive influenza test result, because early therapy provides the best outcomes. Efforts should be made to minimize treatment of patients who are not infected with influenza. Diagnostic tests vary by method, availability, processing time, sensitivity and cost, all of which should be considered in making the best clinical judgment.

Regardless of influenza vaccination status, antiviral treatment should be offered as early as possible to the following individuals:

• Any hospitalized child with suspected or confirmed influenza.
• Any hospitalized child with severe, complicated or progressive illness attributable to influenza regardless of duration of symptoms.
• Children with suspected influenza (of any severity) and at high risk of complications.

Treatment may be considered for the following individuals:

• Any otherwise healthy child suspected to have influenza. The greatest effect on outcome is expected to occur if treatment can be initiated within 48 hours of illness onset but still should be considered if later in the course of progressive, symptomatic illness.
• Children suspected to have influenza and whose siblings or household contacts either are younger than 6 months or have underlying medical conditions that predispose them to complications of influenza.

 Highlights for the 2018-’19 influenza season

• Vaccination remains the best available preventive measure against influenza illness.
• The annual influenza vaccine is recommended for everyone 6 months and older.
• Vaccination can begin as soon as the seasonal influenza vaccine is available and should be completed preferably by the end of October.
• Inactivated influenza vaccine (IIV3 or IIV4) is the primary vaccine choice for all children.
• Quadrivalent live attenuated influenza vaccine (LAIV4) may be used for children who would not otherwise receive a vaccine (e.g., refusal of IIV) and for whom it is appropriate by age (2 years of age and older) and health status (healthy, without any underlying chronic medical condition).
• Pregnant women may receive IIV at any time during pregnancy. Vaccination during pregnancy can protect infants in the first 6 months of life, when they are too young to be vaccinated, through transplacental transfer of antibodies.
• Vaccination is safe during breastfeeding for mothers and their infants.
• All health care personnel should receive an annual influenza vaccine, a crucial step in preventing influenza and reducing health care-associated influenza infections.
• Antiviral medications are important in the treatment of influenza but are not a substitute for influenza vaccination.

Dr. Bernstein is a member of the Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention, associate editor of Red Book Online and an ex officio member of the AAP Committee on Infectious Diseases (COID). Dr. Munoz is a member of COID. Y. Amanda Wang, B.A., and Caroline Braun, B.A., clinical research assistants at Cohen Children’s Medical Center, contributed to this article.