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By contactus@priority-pediatrics.com
September 08, 2017
Category: Immunizations
Tags: Influenza   Flu   Vaccines   flu shot   flu vaccine   Tamiflu   guidelines   recommendations   the flu  

The American Academy of Pediatrics (AAP) recommends annual seasonal influenza vaccination for everyone 6 months and older, including children and adolescents, during the 2017–2018 influenza season.

 

Special effort should be made to vaccinate individuals in the following groups:

  • All children, including infants born preterm, 6 months and older (on the basis of chronologic age) with conditions that increase the risk of complications from influenza (eg, children with chronic medical conditions such as pulmonary diseases like asthma, metabolic diseases like diabetes mellitus, hemoglobinopathies like sickle cell disease, hemodynamically significant cardiac disease, immunosuppression, or neurologic and neurodevelopmental disorders);

  • All household contacts and out-of-home care providers of children with high-risk conditions or younger than 5 years, especially infants younger than 6 months;

  • Children and adolescents (6 months through 18 years of age) receiving an aspirin- or salicylate-containing medication, which places them at risk for Reye syndrome after influenza virus infection;

  • American Indian/Alaskan native children;

  • All health care personnel (HCP);

  • All child care providers and staff; and

  • All women who are pregnant, are considering pregnancy, are in the postpartum period, or are breastfeeding during the influenza season.

Current Recommendations

Seasonal influenza vaccination with a flu shot is recommended for all children 6 months and older. Nasal spray vaccine should not be used. Children and adolescents with certain underlying medical conditions, listed below, have an elevated risk of complications from influenza:

  • asthma or other chronic pulmonary diseases, including cystic fibrosis;

  • hemodynamically significant cardiac disease;

  • immunosuppressive disorders or therapy;

  • HIV infection;

  • sickle cell anemia and other hemoglobinopathies;

  • diseases that necessitate long-term aspirin therapy or salicylate-containing medication, including juvenile idiopathic arthritis or Kawasaki disease, that may place a child at increased risk of Reye syndrome if infected with influenza;

  • chronic renal dysfunction;

  • chronic metabolic disease, including diabetes mellitus;

  • any condition that can compromise respiratory function or handling of secretions or can increase the risk of aspiration, such as neurodevelopmental disorders, spinal cord injuries, seizure disorders, or neuromuscular abnormalities; and

  • pregnancy.

Additional vaccination efforts should be made for the following groups to prevent transmission of influenza to those at risk, unless contraindicated:

  • Household contacts and out-of-home care providers of children younger than 5 years and of at-risk children of all ages;

  • Any woman who is pregnant or considering pregnancy, is in the postpartum period, or is breastfeeding during the influenza season. It is safe to administer the influenza vaccine to pregnant women during any trimester. Any licensed, recommended, and age-appropriate flu vaccine may be used. Studies have revealed that infants born to immunized women have better influenza-related health outcomes than infants of unimmunized women. However, according to Internet-based panel surveys conducted by the CDC, only ∼50% of pregnant women during the 2015–2016 influenza season and 47% of women during the 2016–2017 season (according to preliminary data) reported receiving an influenza vaccine, even though both pregnant women and their newborn infants are at higher risk of complications from the flu. More data on the safety of influenza vaccination in the early first trimester are becoming available. First trimester flu vaccine was not associated with an increase in the rates of major congenital malformations. Similarly, no association between congenital defects and influenza vaccination in any trimester, including the first trimester’s gestation, were seen in a large study. Assessments of any association with influenza vaccination and preterm birth and small-for-gestational-age infants have revealed inconsistent results, with the authors of most studies reporting a protective effect or no association against these outcomes. Breastfeeding is also recommended to protect against influenza viruses by activating innate antiviral mechanisms in the baby, specifically type 1 interferons. In addition, human milk from mothers vaccinated during the third trimester contains higher levels of influenza-specific immunoglobulin A. Greater exclusivity of breastfeeding in the first 6 months of life decreases the episodes of respiratory illness with fever in infants of vaccinated mothers. 

  • American Indian/Alaskan native children and adolescents;

  • Close contacts of immunosuppressed people.

Key Points Relevant for the 2017–2018 Influenza Season

 1. The annual seasonal influenza vaccine is recommended for everyone 6 months and older, including children and adolescents, during the 2017–2018 influenza season.   It is important that household contacts and out-of-home care providers of children younger than 5 years, especially infants younger than 6 months, and children of any age at high risk for complications from influenza (eg, children with chronic medical conditions such as pulmonary diseases like asthma, metabolic diseases like diabetes mellitus, hemoglobinopathies like sickle cell disease, hemodynamically significant cardiac disease, immunosuppression, or neurologic and neurodevelopmental disorders) receive the annual influenza vaccine. In the United States, more than two-thirds of children younger than 6 years and almost all children 6 years and older spend significant time in child care or school settings outside the home. Exposure to groups of children increases the risk of contracting infectious diseases. Children younger than 2 years are at increased risk of hospitalization and complications attributable to influenza. School-aged children bear a large influenza disease burden and have a significantly higher chance of seeking influenza-related medical care compared with healthy adults. Reducing influenza virus transmission (eg, by using appropriate hand hygiene and respiratory hygiene and/or cough etiquette) among children who attend out-of-home child care or school has been shown to decrease the burden of childhood influenza and transmission of influenza virus to household contacts and community members of all ages.

2. The 2016–2017 influenza season was moderate overall, and influenza A (H3N2) viruses predominated.   Severity indicators were within the range of what has been observed during previous H3N2-predominant seasons, which have been associated with more severe illness and mortality, especially in older individuals and younger children, compared with seasons during which H1N1 or B viruses predominated. The start of the season was typical in the United States, with increasing activity noted in mid-December 2016 and peak activity in late February. The majority of circulating strains matched vaccine strains well. Pediatric hospitalizations and deaths caused by influenza vary by the predominant circulating strain and from one season to the next. Historically, 80% to 85% of pediatric deaths have occurred in unvaccinated children 6 months and older. Influenza vaccination is associated with reduced risk of laboratory-confirmed influenza-related pediatric death. In the past 10 seasons, the rates of influenza-associated hospitalization for children younger than 5 years have always exceeded the rates for children 5 through 17 years of age. However, among healthy children hospitalized with influenza B, those 10 to 16 years of age were found to be at the highest risk for admission to the ICU. As of August 19, 2017, the following data were reported by the Centers for Disease Control and Prevention (CDC) during the 2016–2017 influenza season:

  • •104 laboratory-confirmed influenza-associated pediatric deaths occurred:

    • ∘ 66 of these were associated with influenza A viruses;

    • ∘ 37 of these were associated with influenza B viruses; and

    • ∘ 1 of these was associated with an undetermined type of influenza virus.

  1. Although children with certain conditions are at a higher risk of complications, 53.7% of the deaths during the 2016–2017 influenza season occurred in children with no high-risk underlying medical condition. Among children hospitalized with influenza and for whom medical record data were available, ∼41% had no recorded underlying condition, whereas ∼29% had underlying asthma or reactive airway disease. In a recent study of hospitalizations for influenza A versus B, the odds of mortality were significantly greater with influenza B than with A and were not entirely explained by underlying health conditions.

3. Vaccination remains the best available preventive measure against influenza.  Given the unpredictable nature of influenza each season, any licensed and age-appropriate influenza vaccine available should be used. The vaccine strains are predicted to match the circulating strains with the intent of providing optimal protection. Vaccination is effective in reducing outpatient medical visits for illness caused by circulating influenza viruses by 50% to 75%. The universal administration of the seasonal vaccine to everyone 6 months and older is the best strategy available for preventing illness from influenza. There is notable room for improvement in influenza vaccination, because overall influenza vaccination rates have been suboptimal during the past 7 seasons in both children (percentages in the mid- to high- 50s) and adults (percentages in the low- to mid- 40s). A child’s likelihood of being immunized according to recommendations appears to be associated with the immunization practices of their parents. The authors of 1 study found that children were 2.77 times more likely to also be immunized for seasonal influenza if their parents were immunized. When parents who were previously not immunized had received immunization for seasonal influenza, their children were 5.44 times more likely to become immunized for influenza.

4. The number of seasonal influenza vaccine doses to be administered in the 2017–2018 influenza season depends on the child’s age at the time of the first administered dose and vaccine history (Fig 2).

  • • Influenza vaccines are not licensed for administration to infants younger than 6 months;

  • • Children 9 years and older need only 1 dose; and

  • • Children 6 months through 8 years of age:

    • ∘ Need 2 doses if they have received fewer than 2 doses of any influenza vaccine before July 1, 2017. The interval between the 2 doses should be at least 4 weeks; and

    • ∘ Require only 1 dose if they have previously received 2 or more total doses of any influenza vaccine before July 1, 2017. The 2 previous doses do not need to have been received during the same influenza season or consecutive influenza seasons. Despite recent evidence for poor effectiveness of nasal spray flu vaccine in the past, it is still expected to have primed a child’s immune system; there currently are no data that suggest otherwise. Therefore, children who received 2 or more doses of nasal spray flu vaccine before July 1, 2017 may receive only 1 dose of flu shot for the 2017–2018 season.

Any available, age-appropriate influenza vaccine can be used. A child who receives only 1 of the 2 doses as a quadrivalent formulation is likely to be less primed against the additional B virus.

Vaccination of adult close contacts of children at high risk of influenza-related complications is intended to reduce children’s risk of exposure to influenza (ie, “cocooning”). The practice of cocooning also will help protect infants younger than 6 months who are too young to be immunized with an influenza vaccine.

5. Pregnant women may receive an influenza vaccine at any time during pregnancy.   Pregnant women are of special concern because they are at an increased risk for complications from influenza. Any licensed, recommended, and age-appropriate influenza vaccine may be used. Substantial data indicate that the flu vaccine does not cause fetal harm when administered to a pregnant woman, although data on the safety of influenza vaccination in the early first trimester are limited. Assessments of any association with influenza vaccination and preterm birth and small-for-gestational-age infants have yielded inconsistent results, with most studies reporting a protective effect or no association with these outcomes. Vaccination of pregnant women also provides protection for their infants, potentially for as long as 6 months, through the transplacental transfer of antibodies. For example, one recent study documented that infants born to women reporting influenza vaccination during pregnancy had risk reductions of 70% for laboratory-confirmed influenza and 81% for influenza hospitalizations in the first 6 months of life.

 

6. As soon as the seasonal influenza vaccine becomes available locally, pediatricians or vaccine administrators should encourage immunization of HCP, notify parents and caregivers of vaccine availability and the importance of annual vaccination, and immunize children 6 months and older per recommendations, especially those at high risk of complications from influenza. Vaccination should occur by the end of October, if possible.  This is particularly important for children who need 2 doses of the influenza vaccine to achieve optimal protection before the circulation of influenza viruses in the community. Children should receive their first dose as soon as possible after a vaccine becomes available, to allow sufficient time for receipt of the second dose ≥4 weeks later, preferably by the end of October. Prompt initiation of influenza vaccination and continuing to vaccinate throughout the influenza season, whether influenza is circulating (or has circulated) in the community, are important components of an effective vaccination strategy. Although there is no evidence that waning immunity from early administration of the vaccine increases the risk of infection in children, recent reports raise the possibility that early vaccination of adults, particularly the elderly, might contribute to reduced protection later in the influenza season. Older adults are recognized to have a less robust immune response to influenza vaccines. A recent multiseason analysis from the US Influenza Vaccine Effectiveness Network found that vaccine effectiveness declined by ∼7% per month for H3N2 and influenza B and by 6% to 11% per month for H1N1pdm09 in individuals 9 years and older. Vaccine effectiveness remained >0 for at least 5 to 6 months after vaccination. Until there are definitive data that determine if waning immunity influences vaccine effectiveness in children, the administration of the influenza vaccine should not be delayed to a later date, because this increases the likelihood of missing the influenza vaccination altogether. Further evaluation is needed before any policy change in timing is made. An early onset of the influenza season is another concern about delayed vaccination.

7. Providers may continue to offer vaccines until June 30 of each year, the date marking the end of the influenza season, because influenza is unpredictable. Protective immune responses generally persist in children throughout the influenza season. Although peak influenza activity in the United States tends to occur from January through March, influenza activity can occur in early fall (October) or late spring (end of May) and may have more than 1 disease peak. This approach also provides ample opportunity to administer a second dose of the vaccine to children 6 months through 8 years of age when indicated, as detailed previously. This approach also allows for optimal ability to immunize travelers, particularly international travelers, who may be exposed to influenza year round, depending on destination.

8. Antiviral medications are important in the control of influenza but are not a substitute for influenza vaccination. The neuraminidase inhibitors (NAIs) oral oseltamivir (Tamiflu [Roche Laboratories, Nutley, NJ]) and inhaled zanamivir (Relenza [GlaxoSmithKline, Research Triangle Park, NC]) are the only antiviral medications that are recommended for chemoprophylaxis or treatment of influenza in children during the 2017–2018 season. Recent viral surveillance and resistance data from CDC and the World Health Organization (WHO) indicate that the majority of currently circulating influenza viruses likely to cause influenza in North America during the 2017–2018 season continue to be susceptible to oseltamivir and zanamivir. 

In children, the most common injection site adverse reactions after administration of the flu vaccine were pain, redness, and swelling. The most common general sytemic adverse events were drowsiness, irritability, loss of appetite, fatigue, muscle aches, headache, arthralgia, and gastrointestinal tract symptoms.

9. A large body of scientific evidence demonstrates that thimerosal-containing vaccines are not associated with increased risk of autism spectrum disorders in children. Thimerosal from vaccines has not been linked to any medical condition. As such, the AAP extends its strongest support to the current WHO recommendations to retain the use of thimerosal as a preservative in multiuse vials in the global vaccine supply. Some people may still raise concerns about the trace amount of thimerosal in some IIV vaccine formulations, and in some states, including California, Delaware, Illinois, Missouri, New York, and Washington, there is a legislated restriction on the use of thimerosal-containing vaccines. The benefits of protecting children against the known risks of influenza are clear. Therefore, to the extent authorized by state law, children should receive any available formulation of IIV rather than delaying vaccination while waiting for reduced thimerosal-content or thimerosal-free vaccines. Although some flu shot formulations contain a trace amount of it, thimerosal-free vaccine products can be obtained. Vaccine manufacturers are delivering increasing amounts of thimerosal-free influenza vaccine each year. Priority Pediatrics uses a thimerosal-free influenza vaccine product. 

10. Influenza Vaccines and Egg Allergies. The flu vaccine administered in a single, age-appropriate dose is well tolerated by recipients with an egg allergy of any severity. Special precautions for egg-allergic recipients of the flu vaccine are not warranted, because the rate of anaphylaxis after flu shot administration is no greater in egg-allergic than in non–egg-allergic recipients or from other universally recommended vaccines. Standard vaccination practice for all vaccines in children should include the ability to respond to rare acute hypersensitivity reactions. Patients who refuse to receive an egg-based vaccine may be vaccinated with an age-appropriate recombinant or cell-cultured product.

Contraindications and Precautions

Minor illnesses, with or without fever, are not contraindications to the use of influenza vaccines, particularly among children with mild upper respiratory infection symptoms or allergic rhinitis. Children diagnosed with a moderate to severe febrile illness, on the basis of the judgment of the clinician, should not be vaccinated with a flu vaccine until resolution of the illness. Infants younger than 6 months should also not be vaccinated with the flu vaccine as it is not approved at this age. A previous severe allergic reaction to an influenza vaccine (ie, anaphylaxis involving cardiovascular changes, respiratory or gastrointestinal tract symptoms, or reactions that necessitate the use of epinephrine), regardless of the component suspected of being responsible for the reaction, is a contraindication to future receipt of the vaccine.

The estimated risk for Guillain-Barré syndrome (GBS) is low, especially in children. Although influenza infection is recognized to be a cause of GBS, there is no elevated risk of GBS from influenza vaccination. As a precaution, people who are not at high risk for severe influenza and who are known to have experienced GBS within 6 weeks of influenza vaccination generally should not be vaccinated. However, the benefits of influenza vaccination might outweigh the risks for certain people who have a history of GBS and who also are at high risk for severe complications from influenza.