H1N1 Flu

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Content on this page was developed during the 2009-2010 H1N1 pandemic and has not been updated.

The H1N1 virus that caused that pandemic is now a regular human flu virus and continues to circulate seasonally worldwide.
The English language content on this website is being archived for historic and reference purposes only.
For current, updated information on seasonal flu, including information about H1N1, see the CDC Seasonal Flu website.

2009 H1N1 Monovalent Influenza Vaccine Dosage, Administration, and Storage

December 28, 2009, 6:00 PM EDT

This document has been revised to include updated information related to FDA approval of the GSK 2009 H1N1 monovalent influenza vaccine to be used in persons ages 18 years old and older and the expanded use of CSL 2009 H1N1 monovalent influenza vaccine to younger age groups.

Inactivated Vaccine: Dosage, Administration, and Storage

The composition of the influenza A (H1N1) 2009 monovalent inactivated influenza vaccine varies according to manufacturer, and package inserts should be consulted. Inactivated vaccine formulations in multidose vials contain the vaccine preservative thimerosal; preservative-free, single-dose preparations also are available. Inactivated vaccine should be stored at 35°F to 46°F (2°C to 8°C) and should not be frozen. Inactivated vaccine that has been frozen should be discarded. Dosage recommendations and schedules vary according to age group (Table 1).

The intramuscular route is recommended for administering the influenza A (H1N1) 2009 monovalent inactivated vaccine. Adults and older children should be vaccinated in the deltoid muscle. A needle length of 1 inch or longer (25 mm or longer) should be considered for persons in these age groups because needles of less than 1 inch might be of insufficient length to penetrate muscle tissue in certain adults and older children. When injecting into the deltoid muscle in children with adequate deltoid muscle mass, a needle length of 7/8” to 1.25 inches is recommended.

Infants and young children should be vaccinated in the anterolateral aspect of the thigh. A needle length of 7/8” to 1 inch should be used for children younger than 12 months of age.

Live Attenuated Influenza Vaccine (LAIV): Dosage, Administration, and Storage

The 2009 H1N1 monovalent LAIV contains the same vaccine antigen as the inactivated vaccine. However, the antigen is constituted as a live, attenuated, cold-adapted, temperature-sensitive vaccine virus. Providers should refer to the package insert, which contains additional information about the formulation of this vaccine and other vaccine components. LAIV does not contain thimerosal. LAIV is made from an attenuated virus that is able to replicate efficiently only at temperatures present in the nasal mucosa. LAIV does not cause systemic symptoms of influenza in vaccine recipients, although a minority of recipients experience nasal congestion or fever, which is probably a result of the effects of intranasal vaccine administration or local viral replication or fever.

LAIV is intended for intranasal administration only and should not be administered by the intramuscular, intradermal, or intravenous route. LAIV is not licensed for vaccination of children younger than 2 years or adults older than 49 years of age. LAIV is supplied in a prefilled, single-use sprayer containing 0.2 mL of vaccine. Approximately 0.1 mL (i.e., half of the total sprayer contents) is sprayed into the first nostril while the recipient is in the upright position. An attached dose-divider clip is removed from the sprayer to administer the second half of the dose into the other nostril while the recipient is in the upright position. LAIV is shipped at 35°F to 46°F (2°C to 8°C). LAIV should be stored at 35°F to 46°F (2°C to 8°C) on receipt and can remain at that temperature until the expiration date is reached.

**TABLE 1. Influenza A (H1N1) 2009 monovalent vaccines approved for use in the United States, November 11, 2009**
Vaccine type	Manufacturer	Presentation	Mercury content (μg Hg/0.5 mL dose)	Age group	No. of doses	Route
Inactivated*	Sanofi Pasteur	0.25 mL prefilled syringe	0	6–35 mos	2†	Intra- muscular§
		0.5 mL prefilled syringe	0	≥36 mos	1 or 2†	Intra- muscular
		5.0 mL multidose vial	25.0	≥6 mos	1 or 2†	Intra- muscular
Inactivated*	Novartis Vaccines and Diagnostics Limited	5.0 mL multidose vial	25.0	≥4 yrs	1 or 2†	Intra- muscular
Inactivated*	Novartis Vaccines and Diagnostics Limited	0.5 mL prefilled syringe	<1.0	≥4 yrs	1 or 2†	Intra- muscular
Inactivated*	CSL Limited	0.5 mL prefilled syringe	0	6–35 mos§§	2†	Intra- muscular
		0.5 mL prefilled syringe	0	≥3 yrs	1	Intra- muscular
		5.0 mL multidose vial	24.5	≥6 mos¶¶	1 or 2†	Intra- muscular
Inactivated*	ID Biomedical (Distributed by GSK)	5.0 mL multidose vial	25.0	≥18 yrs	1	Intra- muscular
LAIV¶	MedImmune LLC	0.2 mL sprayer**	0	2–49 yrs	1 or 2††	Intranasal
* A 0.5-mL dose contains 15 μg hemagglutinin of A/California/7/2009 (H1N1)pdm. † Two doses administered approximately 4 weeks apart (≥21 days acceptable) are recommended for children aged 6 months through 9 years. § The preferred site for infants and young children is the anterolateral aspect of the thigh. ¶ Live attenuated influenza vaccine. A 0.2-mL dose contains 106.5--7.5 fluorescent focal units of live attenuated influenza virus reassortants of A/California/7/2009 (H1N1)pdm. ** Influenza A (H1N1) 2009 LAIV is shipped refrigerated and stored in the refrigerator at 36°F to 46°F (2°C to 8°C) after arrival in the immunization clinic. The dose is 0.2 mL divided equally between each nostril. LAIV should not be administered to persons with asthma. Healthcare providers should consult the medical record, when available, to identify children aged 2 through 4 years old with asthma or recurrent wheezing that might indicate asthma. In addition, to identify children who might be at greater risk for asthma and possibly at increased risk for wheezing after receiving LAIV, parents or caregivers of children aged 2 through 4 years of age should be asked: "In the past 12 months, has a healthcare provider ever told you that your child had wheezing or asthma?" Children whose parents or caregivers answer "yes" to this question and children who have asthma or who had a wheezing episode noted in the medical record during the preceding 12 months should not receive LAIV. †† Two doses administered approximately 4 weeks apart are recommended for children aged 2 through 9 years of age. §§ The CDC recommends the CSL™ 2009 H1N1 0.5 mL pre-filled syringe vaccine formulation be given to children ages 6 through 35 months ONLY when other age appropriate formulations are not available. This recommendation is not related to vaccine efficacy or safety concerns. It was made to reduce vaccine wastage. If providers choose to immunize children ages 6 through 35 months, using the CSL pre-filled syringe vaccine formulation, the dose is 0.25 mL. For additional guidance, refer to “Updated Guidance for the Use of CSL’s 2009 H1N1 Monovalent Vaccine”. ¶¶ The CSL™ 2009 H1N1 5 mL multi-dose vial vaccine formulation is recommended for use in persons 6 months and older. The quantities of ancillary supplies provided with each order are sufficient to administer 10 doses per vial. Providers who choose to administer more than 10 doses per vial will need to supplement their own ancillary supplies. For additional guidance, refer to “Updated Guidance for the Use of CSL’s 2009 H1N1 Monovalent Vaccine”.