Update on Vaccination Guidelines for Older Adults
Influenza affects older adults disproportionately. On average, there are 23,000 influenza-related deaths in the United States annually, 90% of which occur in individuals aged 65 and older. Acute respiratory failure attributed to influenza is 10 to 30 times as likely to affect older as younger adults. Universal vaccination for adults aged 65 and older has been a mainstay of ACIP influenza vaccine recommendations, but the last few years have shown tremendous growth in the types of influenza vaccines and the methods for administering them.
The high burden of disease has led to development of new influenza vaccine products and more-nuanced guidelines. Currently licensed influenza vaccine products are classified as inactivated influenza vaccine (IIV), live attenuated influenza vaccine, and recombinant influenza vaccine. The only vaccine class currently approved for use in individuals aged 65 and older is the IIV, which includes different vaccine types or formulations that are described below.
IIV is conventionally given as an intramuscular injection. There is a version that can be administered intradermally, but this is approved only for adults aged 18 to 64 and requires a specially designed microinjection system. Historically, three different strains of the hemagglutinin antigen have been included (trivalent influenza vaccine or IIV3). Two strains of influenza A (such as H1N1 and H3N2) and one strain of B are included. IIV3 is recommended for everyone aged 6 months and older. Choosing one of two possible influenza B strains can lead to a significant gap in vaccine coverage. Therefore, a vaccine was developed that included B strains in addition to the two influenza A strains. In 2013, the quadrivalent influenza vaccine (IIV4) was licensed and approved for everyone aged 6 months and older.
There is now a high-dose formulation of IIV3 approved only for adults aged 65 and older. It includes four times the amount of hemagglutinin for each strain. Better hemagglutinin inhibitory antibody titers and greater rates of seroconversion are found in response to high-dose influenza vaccine than with the standard dose. It has a tendency to elicit more injection site reactivity, but that is well tolerated. A recently published clinical efficacy study of more than 30,000 participants demonstrated 24% greater efficacy of high-dose IIV than of the standard dose, reducing the breakthrough incidence of laboratory-confirmed influenza from 1.9% to 1.5%.
The virus used for inactivated influenza vaccines is grown in eggs, which can lead to residual egg protein in the formulation. Although reactions are rare, an individual's allergic response to egg products must be considered when administering the IIV. If the reaction is only hives, then administering IIV is appropriate, although the vaccine recipient should be observed for at least 30 minutes after each vaccine dose. For a history of more-serious reactions to egg, such as angioedema or respiratory distress, an allergist should be consulted. There has been an effort to circumvent the need for eggs. A recombinant influenza vaccine bypasses the need for eggs and is the only vaccine approved for administration to someone with a severe egg allergy, but the recombinant influenza vaccine is recommended only for individuals aged 18 to 49. An inactivated influenza virus propagated in cell culture has been developed (ccIIV3) and approved for individuals aged 18 and older, but because the initial virus was from stock propagated in egg, it is technically not free from egg protein, containing an estimated 10 g of protein per dose (vs 10 g/dose of IIV) and therefore did not meet strict criteria for administration to individuals with egg anaphylaxis.
Vaccinating all adults for influenza is a long-standing preventative health measure. In individuals aged 65 and older, the inactivated influenza virus is still the approved mainstay, but in addition to standard-dose IIV3, this now includes quadrivalent vaccine (IIV4), high-dose trivalent vaccine, and cell culture trivalent vaccine. The current ACIP recommendation states that immunization should occur with any of these vaccines, without a preferential recommendation for any of them. Expanded understanding of vaccine responses has paved the way for new products, and ongoing updates are expected as knowledge continues to grow.
Influenza
Influenza affects older adults disproportionately. On average, there are 23,000 influenza-related deaths in the United States annually, 90% of which occur in individuals aged 65 and older. Acute respiratory failure attributed to influenza is 10 to 30 times as likely to affect older as younger adults. Universal vaccination for adults aged 65 and older has been a mainstay of ACIP influenza vaccine recommendations, but the last few years have shown tremendous growth in the types of influenza vaccines and the methods for administering them.
The high burden of disease has led to development of new influenza vaccine products and more-nuanced guidelines. Currently licensed influenza vaccine products are classified as inactivated influenza vaccine (IIV), live attenuated influenza vaccine, and recombinant influenza vaccine. The only vaccine class currently approved for use in individuals aged 65 and older is the IIV, which includes different vaccine types or formulations that are described below.
IIV is conventionally given as an intramuscular injection. There is a version that can be administered intradermally, but this is approved only for adults aged 18 to 64 and requires a specially designed microinjection system. Historically, three different strains of the hemagglutinin antigen have been included (trivalent influenza vaccine or IIV3). Two strains of influenza A (such as H1N1 and H3N2) and one strain of B are included. IIV3 is recommended for everyone aged 6 months and older. Choosing one of two possible influenza B strains can lead to a significant gap in vaccine coverage. Therefore, a vaccine was developed that included B strains in addition to the two influenza A strains. In 2013, the quadrivalent influenza vaccine (IIV4) was licensed and approved for everyone aged 6 months and older.
There is now a high-dose formulation of IIV3 approved only for adults aged 65 and older. It includes four times the amount of hemagglutinin for each strain. Better hemagglutinin inhibitory antibody titers and greater rates of seroconversion are found in response to high-dose influenza vaccine than with the standard dose. It has a tendency to elicit more injection site reactivity, but that is well tolerated. A recently published clinical efficacy study of more than 30,000 participants demonstrated 24% greater efficacy of high-dose IIV than of the standard dose, reducing the breakthrough incidence of laboratory-confirmed influenza from 1.9% to 1.5%.
The virus used for inactivated influenza vaccines is grown in eggs, which can lead to residual egg protein in the formulation. Although reactions are rare, an individual's allergic response to egg products must be considered when administering the IIV. If the reaction is only hives, then administering IIV is appropriate, although the vaccine recipient should be observed for at least 30 minutes after each vaccine dose. For a history of more-serious reactions to egg, such as angioedema or respiratory distress, an allergist should be consulted. There has been an effort to circumvent the need for eggs. A recombinant influenza vaccine bypasses the need for eggs and is the only vaccine approved for administration to someone with a severe egg allergy, but the recombinant influenza vaccine is recommended only for individuals aged 18 to 49. An inactivated influenza virus propagated in cell culture has been developed (ccIIV3) and approved for individuals aged 18 and older, but because the initial virus was from stock propagated in egg, it is technically not free from egg protein, containing an estimated 10 g of protein per dose (vs 10 g/dose of IIV) and therefore did not meet strict criteria for administration to individuals with egg anaphylaxis.
Vaccinating all adults for influenza is a long-standing preventative health measure. In individuals aged 65 and older, the inactivated influenza virus is still the approved mainstay, but in addition to standard-dose IIV3, this now includes quadrivalent vaccine (IIV4), high-dose trivalent vaccine, and cell culture trivalent vaccine. The current ACIP recommendation states that immunization should occur with any of these vaccines, without a preferential recommendation for any of them. Expanded understanding of vaccine responses has paved the way for new products, and ongoing updates are expected as knowledge continues to grow.
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