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Recommendations for the Use of Influenza Vaccines, 2013–14 Influenza Season

Groups Recommended for Vaccination 
Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. Recommendations pertaining to the use of specific vaccines and populations are summarized below.

Timing of Vaccination 
In general, health-care providers should begin offering vaccination soon after vaccine becomes available and, if possible, by October. All children aged 6 months through 8 years who are recommended for 2 doses should receive their first dose as soon as possible after vaccine becomes available; these children should receive the second dose ≥4 weeks later. This practice increases the opportunity for both doses to be administered before or shortly after the onset of influenza activity. To avoid missed opportunities for vaccination, providers should offer vaccination during routine health-care visits or during hospitalizations whenever vaccine is available.

Available Vaccine Products and Indications 
No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one product is otherwise appropriate. A variety of influenza vaccine products are available (Table 1), including (as of August 2013) six newly approved vaccines (see New and Recently Approved Influenza Vaccine Products). For many vaccine recipients, more than one type or brand of vaccine may be appropriate within indications and ACIP recommendations. Considerations for selection of a given vaccine when several appropriate options are available are discussed below. However, not all products are likely to be uniformly available in any practice setting or locality. For newer vaccines, supplies might be limited during the 2013–14 season; moreover, postmarketing safety and effectiveness data are as yet unavailable, prohibiting a full risk-benefit analysis of newer versus previously available products. Therefore, within these guidelines and approved indications, where more than one type of vaccine is appropriate and available, no preferential recommendation is made for use of any influenza vaccine product over another.

Inactivated Influenza Vaccines 
IIVs comprise a large group of products. For the 2013–14 season, most IIVs will be trivalent (IIV3), with some quadrivalent (IIV4) also available. Among IIV3 preparations, cell-culture based IIV will be available (ccIIV3). As a class, IIVs include products which might be administered to all persons aged ≥6 months. However, approved age indications for the various IIV products differ (Table 1). Only age-appropriate products should be administered. Providers should consult package inserts and updated CDC/ACIP guidance for current information. Of particular note, although Afluria (CSL Limited) is FDA-approved for children aged >5 years, CDC and ACIP recommend against use of Afluria in persons aged <9 years because of increased risk for febrile reactions noted in this age group with CSL's 2010 Southern Hemisphere IIV3. If no other age-appropriate, licensed inactivated seasonal influenza vaccine is available for a child aged 5 through 8 years who has a medical condition that increases the child's risk for influenza complications, Afluria can be used; however, providers should discuss with the parents or caregivers the potential benefits and risks of influenza vaccination with Afluria in this age group before administering this vaccine.

All IIV preparations contain the same quantity of HA (15 µg per vaccine virus strain per 0.5 mL dose; 45 µg total), except Fluzone Intradermal and Fluzone High-Dose (Sanofi Pasteur). Fluzone Intradermal is approved for persons aged 18 through 64 years, and contains 9 µg of each HA per vaccine virus strain (27 µg total). Fluzone High-Dose is approved for persons aged ≥65 years and contains 60 µg of each HA per vaccine virus strain (180 µg total). Within specified age indications, ACIP expresses no preference for any given IIV over another.

The one IIV product licensed by FDA for children aged 6 through 36 months contains 0.25 mL/dose. The 0.25 mL dose may be administered from a prefilled single-dose syringe, single-use vial, or multi-dose vial of this age-appropriate formulation. Children aged 36 months through 18 years, and adults receiving IM preparations of IIV, should receive a 0.5 mL dose. If a pediatric vaccine dose (0.25 mL) is administered inadvertently to an adult, an additional pediatric dose (0.25 mL) should be administered to provide a full adult dose (0.5 mL). If the error is discovered later (after the patient has left the vaccination setting), an adult dose should be administered as soon as the patient can return. Vaccination with a formulation approved for adult use should be counted as a dose if inadvertently administered to a child.

With the exception of Fluzone Intradermal (Sanofi Pasteur), IIVs should be administered intramuscularly. For adults and older children, the deltoid is the preferred site. Infants and younger children should be vaccinated in the anterolateral thigh. Additional specific guidance regarding site selection and needle length for intramuscular administration are provided in ACIP's General Recommendations on Immunization. Fluzone Intradermal is administered intradermally, preferably over the deltoid muscle, using the included delivery system.

Trivalent versus Quadrivalent IIVs: For the first time, during the 2013–14 influenza season, both trivalent (IIV3) and quadrivalent (IIV4) IIVs will be available. The relative quantity of doses of IIV4 that will be available is not certain; however, it is expected that the supply of IIV4 might be limited. Quadrivalent vaccines are designed to provide broader protection against circulating influenza B viruses in seasons during which the B virus contained in trivalent vaccines is not an optimal match to the predominant circulating B viruses. However, vaccination should not be delayed if only IIV3 is available. No preference is expressed for IIV4 over IIV3.

IIVs and persons aged ≥65 years: For persons aged ≥65 years, either an age-appropriate standard-dose IIV (IIV3 or IIV4) or high-dose IIV3 are acceptable options. High-dose IIV3 (available as Fluzone High-Dose) is approved for persons aged ≥65 years. Immunogenicity data from three prelicensure studies among persons aged ≥65 years indicated that, compared with standard dose Fluzone, Fluzone High-Dose elicited higher HAI titers against all three influenza virus strains included in seasonal influenza vaccines recommended during the study period. Whether the higher postvaccination immune responses observed among Fluzone High-Dose vaccine recipients will result in greater protection against influenza illness is under study. Some solicited injection site and systemic adverse events were more frequent after vaccination with Fluzone High-Dose compared with standard Fluzone, but typically were mild and transient. No preferential recommendation is made for high-dose IIV over standard dose IIV for persons aged ≥65 years.

IIVs and egg allergy: With the exception of Flucelvax, IIVs are manufactured via propagation of virus in eggs and therefore might contain residual egg protein. Egg protein content (usually described as ovalbumin content as a surrogate measure) is not disclosed on all package inserts (Table 1); where not listed, this information generally can be obtained by contacting the manufacturer. Flucelvax is manufactured from virus propagated in Madin Darby Canine Kidney (MDCK) cells rather than embryonated eggs; however, before production seed virus is created using reference virus strains supplied by WHO, which have been passaged in eggs. Flucelvax can therefore not be considered egg-free. The total egg protein is estimated to be <50 femtograms (5x10-14 grams) total egg protein (of which a fraction is ovalbumin) per 0.5 mL dose of Flucelvax (Novartis, unpublished data, 2013). Flucelvax can be administered to persons with a history of mild egg allergy (specifically, those who have experienced only hives following egg exposure; see Influenza Vaccination of Persons with Egg Allergy) who are aged ≥18 years and have no other contraindications. Because no data are available regarding the use of ccIIV among egg-allergic persons, and there is no established safe threshold for ovalbumin content in vaccines, ccIIV should be administered according to the guidance for other IIVs (see Influenza Vaccination of Persons with Egg Allergy).

Contraindications and precautions for use of IIVs: Manufacturer package inserts and updated CDC/ACIP guidance should be consulted for current information on contraindications and precautions for individual vaccine products. In general, IIV is contraindicated for, and should not be administered to, persons known to have anaphylactic hypersensitivity to eggs or to any vaccine components (Table 2). Prophylactic use of antiviral agents is an option for preventing influenza among such persons. Information about vaccine components is located in package inserts from each manufacturer.

Moderate or severe acute illness with or without fever is a general precaution for vaccination. GBS within 6 weeks following a previous dose of influenza vaccine is considered a precaution for use of influenza vaccines (Table 2).

Recombinant Influenza Vaccine 
One RIV product, FluBlok, a trivalent recombinant HA vaccine, is expected to be available for the 2013–14 influenza season. This RIV3 is administered by intramuscular injection, and is indicated for persons aged 18 through 49 years. RIV3 is manufactured without the use of influenza viruses; therefore, similarly to IIVs, no shedding of vaccine virus will occur. No preference is expressed for RIV versus IIV within specified indications.

RIV and egg allergy: The currently available RIV, FluBlok, is manufactured without the use of eggs, and does not carry a contraindication for egg allergy. Therefore, Flublok can be administered to persons with egg allergy of any severity who are aged 18 through 49 years and do not have other contraindications. Since 2011, ACIP has recommended that persons with a history of mild egg allergy (specifically, those who experience only hives following egg exposure) can receive IIV, with additional safety precautions. For such persons, vaccination should not be delayed if RIV is not available; IIV should be used in these settings, following the recommendations outlined (see Influenza Vaccination of Persons with Egg Allergy).

Contraindications and precautions for use of RIV: FluBlok is contraindicated in persons who have had a severe allergic reaction to any component of the vaccine. Moderate or severe acute illness with or without fever is a general precaution for vaccination. GBS within 6 weeks following a previous dose of influenza vaccine is considered a precaution for use of influenza vaccines (Table 2). FluBlok is not licensed for use in children aged <18 years or adults aged >49 years.

Live Attenuated Influenza Vaccine 
One LAIV4 product, FluMist Quadrivalent (MedImmune), is expected to be available during the 2013–14 influenza season. Flumist is indicated for nonpregnant persons aged 2 through 49 years who do not have a medical condition that predisposes them to medical complications from influenza. No preference is indicated for LAIV versus other vaccines appropriate for this group.

LAIV is administered intranasally using the supplied 0.2 mL intranasal sprayer (0.1 mL in each nostril). If the vaccine recipient sneezes immediately after administration, the dose should not be repeated. However, if nasal congestion is present that might impede delivery of the vaccine to the nasopharyngeal mucosa, deferral of administration should be considered until resolution of the illness, or IIV should be administered instead.

LAIV versus IIV: Several randomized studies have evaluated the relative effectiveness of LAIV3 as compared with IIV3. Most studies conducted among adults have noted superior relative efficacy of IIV3. A significantly greater relative efficacy of LAIV3 as compared with IIV3 has been noted in several studies conducted among younger children, including a randomized, open label study among children aged 6 through 71 months, a randomized blinded trial of children aged 6 through 59 months, and a randomized blinded trial of children with asthma aged 6 through 17 years. However, no postmarketing safety data are yet available for the new quadrivalent formulation, LAIV4, which will be available for the first time during the 2013–14 season and is expected to replace LAIV3. Therefore, no preferential recommendation is made for LAIV4 over IIV for any age group at this time. This information will be updated as more data become available. Vaccination should not be delayed if LAIV is not available.

LAIV and egg allergy: Because of relative lack of data demonstrating safety of LAIV for persons with egg allergy, egg-allergic persons should receive IIV rather than LAIV (see Influenza Vaccination of Persons with Egg Allergy).

Contraindications and precautions to the use of LAIV: LAIV is contraindicated for persons with a history of severe hypersensitivity reaction to any component of the vaccine or to a previous dose of any influenza vaccine, and in children and adolescents receiving concomitant aspirin therapy (Table 2). In addition, LAIV should not be administered to the following groups:

  • children aged <2 years;
  • adults aged ≥50 years;
  • children aged 2 through 4 years whose parents or caregivers report that a health-care provider has told them during the preceding 12 months that their child had wheezing or asthma or whose medical record indicates a wheezing episode has occurred during the preceding 12 months (Table 1);
  • persons with asthma;
  • children and adults who have chronic pulmonary, cardiovascular (except isolated hypertension), renal, hepatic, neurologic/neuromuscular, hematologic, or metabolic disorders;
  • children and adults who have immunosuppression (including immunosuppression caused by medications or by HIV); and
  • pregnant women.

Moderate or severe acute illness with or without fever is a general precaution for vaccination. GBS within 6 weeks following a previous dose of influenza vaccine is considered a precaution for use of influenza vaccines.

Additional Information Regarding Prevention of Influenza in Specific Populations

[Link to free full-text MMWR article PDF]

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