Vaccination Against Seasonal Influenza in Childhood and Adolescence. CAV-AEP recommendations for the 2011-2012 campaign.

September, 28th 2011

Comité Asesor de Vacunas de la Asociación Española de Pediatría

 

Introduction

Each year, the Comité Asesor de Vacunas de la Asociación Española de Pediatría (Advisory Committee on Vaccines of the Spanish Paediatric Association, CAV-AEP) issues recommendations on vaccination against influenza in children and adolescents. These recommendations are issued before the start of the influenza season. This committee continues to view influenza vaccination as especially beneficial when aimed at individuals, both children and adults, who are in population groups considered at risk. In the event of being infected with the influenza virus, these individuals may, due to their underlying disease or treatment, suffer more complicated and severe forms of the disease or destabilization of the underlying disease, thus increasing the risk of mortality. However, for various reasons, many children and adolescents in these risk groups are still not given this vaccine. Greater involvement is needed by health professionals, health authorities and all social agents to inform the public, especially parents of children and adolescents in those risk groups, on the recommendations for seasonal influenza vaccination.

 

Vaccine Strains for the 2011-2012 Influenza Season

Each year, the World Health Organization (WHO) determines the influenza virus strains to be contained in these vaccines. For the 2011-2012 season, the influenza vaccine will have the same composition, in terms of strains, as the one from the previous 2010-2011 campaign¹. This repetition does not imply any change in the annual vaccination recommendations, since it is common for the immunogenicity induced by the vaccine to decline once the epidemic is over for the year². Therefore, vaccination should be recommended even if the individual was vaccinated for the 2010-2011 season.

Influenza vaccine strains contained on 2011-2012 immunization campaing are shown on table 1.

Table 1. Influenza vaccine strains contained on 2011-2012 immunization season.  (WHO recommendations)1.

- an A/California/7/2009 (H1N1)-like virus* - an A/Perth/16/2009 (H3N2)-like virus - a B/Brisbane/60/2008-like virus

* Influenza A (H1N1) vaccine virus is derived from pandemic influenza A 2009 pandemic virus.

 

Recommendations of the AEP Vaccine Advisory Committee

For children and adolescents, the CAV-AEP recommends influenza vaccination for:

1) Risk groups: Children over six months of age and adolescents with the following conditions or underlying diseases:

- Chronic respiratory disease (e.g., cystic fibrosis, bronchopulmonary dysplasia, asthma and bronchial hyperreactivity.)

- Severe cardiovascular disease (congenital or acquired).

- Chronic metabolic disease (e.g., diabetes, congenital metabolic defects).

- Chronic kidney (e.g., renal failure, nephrotic syndrome) and liver disease.

- Chronic inflammatory bowel disease.

- Congenital or acquired immunodeficiency.

- Functional or anatomical asplenia.

- Cancer.

- Moderate or severe hematologic disease (e.g., hemoglobinopathy, leukemia).

- Chronic neuromuscular disease and moderate-severe encephalopathy.

- Moderate or severe malnutrition.

- Morbid obesity (BMI greater than or equal to three standard deviations).

- Down syndrome and other severe chromosomal disorders.

- Ongoing treatment with acetylsalicylic acid (due to risk of Reye syndrome by wild influenza infection).

- Pregnancy in adolescents.

2) Healthy children over six months of age and healthy adolescents who live with patients at risk

Vaccination is recommended for healthy children over six months of age and healthy adolescents who have no underlying disease but have household contact with (i.e. live with) patients (children or adults) belonging to risk groups.

3) Adults in contact with children and adolescents belonging to risk groups

Seasonal influenza vaccination must be emphasized for all adults who have household contact with (i.e. live with or care for) children and adolescents who belong to risk groups (see Section 1). Family vaccination is especially important when there are infants under six months of age with risk factors, since these babies cannot receive the influenza vaccine. Similarly, the recommendation for influenza vaccination is emphasized for medical personnel working with children.

For the CAV-AEP, influenza vaccination represents a clear and unquestionable health benefit for all these patients and their household contacts.

Children are the main spreaders of influenza in the community (family, school, etc.³) since they eliminate a greater viral load over a longer period of time than adults⁴. The highest incidence rates are found in those under 15 years of age⁵, and the average hospitalization rate for those under five years of age is around 1 in every 1000 healthy children⁶. For these reasons, the CAV-AEP believes that healthy children older than six months, who are not in any of previously mentioned risk groups, may be vaccinated for seasonal influenza if their parents request it or if their pediatrician deems it appropriate. This preventive approach has a clear health benefit that can provide children and adolescents with direct individual protection, and indirectly promotes the protection of the family and community.

The universal influenza vaccination of all children in our community with the available vaccines currently raises several issues and obstacles: 1) The need for adding an annual intramuscular injection to the vaccination schedule, with the problems inherent in its implementation and acceptability, 2) the effectiveness of the trivalent inactivated influenza vaccine in children under two years of age, which is limited but may be improved⁷, and 3) its high cost and the insufficient data on its efficacy in children.

 

PRACTICAL ASPECTS: dosage, conservation, administration and contraindications

Dosage.

To obtain optimal protection against influenza for children under nine years of age, two doses of the vaccine are needed, separated by at least four weeks². The first dose must be administered as soon as the vaccine is available to ensure that both doses are given before the onset of influenza activity, since protection is greatest when both doses are administered during the same influenza season². If the individual has had the correct influenza vaccination with two doses in a past season, one single dose will be sufficient for the current season. Furthermore, if the individual received a single dose of the influenza vaccine for the first time in the previous season (2010-2011), they should only receive one dose of the influenza vaccine in the current season (2011-2012)² since the composition of the vaccine is identical for both campaigns¹.

For children aged nine years and up, a single dose of influenza vaccine is sufficient each season, if indicated².

Administration route and storage.

Administration is through deep intramuscular injection. For small children who are not yet walking, the preferred site for vaccination is the anterolateral thigh, while for other children the deltoids are preferred⁸.

For patients with bleeding disorders or who are being treated with anticoagulants, subcutaneous administration of nonadjuvanted influenza vaccine is recommended⁸.

The vaccine must be stored between 2 ºC and 8 ºC, and applied at room temperature. The validity period is one year.

Contraindications.

Table 2 shows the contraindications for influenza vaccination in children.

Table 2. Contraindications for influenza vaccination.

- Severe allergic reaction (anaphylaxis) to eggs - Severe allergic reaction to the other components of the vaccine - History of severe reaction to previous doses of the vaccine - Children under six months of age - History of Guillain-Barre syndrome

 

Available influenza vaccine products

It is expected that numerous commercial influenza vaccination preparations will be available for this season, all with the same antigenic composition. Various innovative preparations (live attenuated vaccines, adjuvanted vaccines, tetravalent vaccines and cell culture vaccines) are being progressively incorporated, along with alternative administration routes (intradermal, intranasal, etc.). However, the only available vaccines currently approved for use in children under 18 years of age in Spain are the inactivated trivalent preparations⁹, which all prepared by inoculation of virus into chicken eggs, to be administered intramuscularly.

Table 3 shows all available influenza vaccines currently approved for use in Spain for children less than 18 years of age. All vaccines comply with the current WHO recommendation¹ and with the European Union decision for the 2011/2012 campaign¹⁰. Any updates that may be made to this document or to the data sheets will be uploaded to this advisory committee's website^9,11.

 

Table 3. Influenza vaccines available approved for use in children under 18 years in Spain (latest revision: September  September 27, 2011)9.
Trade name (in alphabetical order)	Manufacturer	Vaccine	Presentation	Dosage	Administration route	Age approved
Chiroflu®	Novartis	Subunits, inactivated virus. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Fluarix®	GSK	Split virion, inactivated. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Gripavac®	Sanofi Pasteur MSD	Split virion, inactivated. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Inflexal V®	Berna	Subunits, inactivated virus. Adjuvant/transporter: virosomes	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Influvac®	Solvay Pharma	Subunits, inactivated virus. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Mutagrip®	Sanofi Pasteur MSD	Split virion, inactivated. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Vacuna antigripal Pasteur®	Sanofi Pasteur MSD	Split virion, inactivated. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months
Vacuna Antigripal Polivalente Leti®	Leti	Split virion, inactivated. Without adjuvant.	0.5 mL prefilled siringe	- Over 36 months: 0.5 mL. - Children aged 6-35 months: limited experience. Doses of 0.25 mL or 0.5 mL have been administered.	Intramuscular	≥6 months

 

RECOMMENDATIONS FOR INFLUENZA VACCINATION IN CHILDREN ALLERGIC TO EGGS

For children and adolescents who have egg allergies, the following considerations need to be taken into account²:

- A previous severe allergic reaction to the influenza vaccine, regardless of the suspected component responsible for the reaction, is a contraindication for receiving the influenza vaccine.

- Influenza vaccines currently available in Spain contain small quantities of egg since they are derived from chicken egg cultures.

- History of only urticaria after exposure to egg does not contraindicate influenza vaccine administration.

- History of angioedema, respiratory distress, dizziness and recurrent vomiting immediately or within minutes to hours after exposure to egg, and the use of adrenaline or other urgent medical measures after exposure, is probably related to egg allergies and re-exposure will likely provoke an anaphylactic reaction. The administration of the influenza vaccine is not recommended for these individuals.

- Some people considered allergic to egg may not be, as the allergy may be caused by other components of these vaccines, such as gelatin. Individuals who are able to eat lightly cooked eggs (scrambled eggs, for example) without a reaction are unlikely to be allergic. Conversely, people allergic to egg may tolerate them in baked goods (for example, bread and cakes), but this tolerance does not preclude the possibility of an egg allergy.

- Vaccines should be administered by personnel trained in the quick recognition of allergic reactions, with equipment on hand for the urgent treatment of anaphylaxis.

- The recipient of the vaccine should be monitored for at least 30 minutes after the administration.

- Some measures, such as prick tests and administering the vaccine in two subdoses in two stages, are not recommended.

 

 

Members of the Advisory Committee of Vaccines of the Spanish Paediatric Association

David Moreno-Pérez (DMP), Francisco José Álvarez García (FJAG), Javier Arístegui Fernández (JAF), Francisco Barrio Corrales (FBC), María José Cilleruelo Ortega (MJCO), José María Corretger Rauet (JMCR), José González-Hachero (JGH), Teresa Hernández-Sampelayo Matos (THSM), Manuel Merino Moína (MMM), Luis Ortigosa del Castillo (LOC), Jesús Ruiz-Contreras (JRC).

 

Conflict of interests

DMP has collaborated in educational activities funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD, as a researcher for clinical trials for GlaxoSmithKline and as a consultant on an Astra-Zeneca Advisory Board.

FJAG has collaborated in educational activities funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD.

JAF has collaborated in educational activities and as a researcher in clinical trials funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD.

FBC has collaborated in educational activities funded by GlaxoSmithKline and Sanofi Pasteur MSD and as a researcher in clinical trials for GlaxoSmithKline and Baxter.

MJCO has collaborated in educational activities funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD and as a researcher in clinical trials for Pfizer.

JMCR has collaborated in educational activities funded by GlaxoSmithKline, Sanofi Pasteur MSD and Novartis.

JGH has collaborated in educational activities funded by GlaxoSmithKline, Pfizer, and Sanofi Pasteur MSD.

THSM has collaborated in educational activities funded by Pfizer and Sanofi Pasteur MSD.

MMM has collaborated in educational activities funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD and as a researcher in clinical trials for GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD.

LOC has collaborated in educational activities funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD and as a researcher in clinical trials for GlaxoSmithKline.

JRC has collaborated in educational activities funded by GlaxoSmithKline, Pfizer and Sanofi Pasteur MSD and as a researcher in clinical trials for GlaxoSmithKline and Pfizer.

 

 

References

1. World Health Organization (WHO). Recommended composition of influenza virus vaccines for use in the 2011-2012 northern hemisphere influenza season OMS. Available at: http://www.who.int/wer/2011/wer8610.pdf Accessed: Nobember 13, 2011.

2. Centers for Disease Control and Prevention (CDC). Prevention and Control of Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2011. MMWR. 2011;60:1128-1132. Available at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6033a3.htm?s_cid=mm6033a3_w  Accessed: September 12, 2011.

3. Fraaij PL, Heikkinen T. Seasonal influenza: the burden of disease in children. Vaccine. 2011;29:7524-7528. 

4. Esposito S, Daleno C, Baldanti F, Scala A, Campanini G, Taroni F, et al. Viral shedding in children infected by pandemic A/H1N1/2009 influenza virus. Virol J. 2011;8:349.

5. Silvennoinen H, Peltola V, Vainionpaa R, Ruuskunen O, Heikkinen T. Incidence of influenza-related hospitalizations in different age groups of children in Finland: a 16-year study. Pediatr Infect Dis J. 2011;30:e24-28.   

6. Poehling KA, Edwards KM, Weinberg GA, Szilagyi P, Staat MA, Iwane MK, et al. The underrecognized burden of influenza in young children. N Engl J Med. 2006;355:31-40. 

7. Jefferson T, Rivetti A, Harnden A, Di Pietrantonj C, Demicheli V. Vaccines for preventing influenza in healthy children. Cochrane Database Syst Rev. 2008;(2):CD004879.

8. Centers for Disease Control and Prevention. General recommendations on immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2011;60(No. RR-2):1-64.

9. Comité Asesor de Vacunas de la Asociación Española de Pediatría. Fichas técnicas de vacunas antigripales. Available at: http://vacunasaep.org/profesionales/fichas-tecnicas-vacunas/resultados?diseases=148 Accessed: September 12, 2011.

10. European Centre for Disease Prevention and Control (ECDC). Influenza. Available at: http://www.ecdc.europa.eu/en/healthtopics/influenza/Pages/index.aspx Accessed: September 12, 2011.

11. Comité Asesor de Vacunas de la Asociación Española de Pediatría. Documentos del CAV. Available at: http://vacunasaep.org/documentos?category=0 Accessed: September 12, 2011.