Prevention of Influenza: 2008-2009

Special Feature

Synopsis: The Advisory Committee on Immunization Practices has provided updated recommendations for the influenza season.

Source: CDC. Prevention and control of influenz: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2008. MMWR. 2008;579:1-60. Available at http://www.cdc.gov/mmwr

The yearly update of recommendations for prevention and control of influenza is available. There have been only few changes from last year. The following focuses on areas of particular interest, including those which seem to generate the most questions. Changes for this year are indicated by their italicization.

Who should be vaccinated?

  • All children 6 months to 18 years of age. The inclusion of children age 5 to 18 years is a new recommendaton as is the statement that vaccination of all children 6 months through 4 years of age continue to be a primary focus of vaccination efforts.
  • All adults who wish to reduce the risk of becoming ill with influenza and/or wish to avoid transmitting influenza to others.
  • In both children and adults, those at high risk of influenza complications or of transmission to vulnerable individuals should be a focus of vaccination programs. This includes those with relevant comorbidities, impending pregnancy during the influenza season, residence in chronic care facilities, health care personnel (CP), household contacts and caregivers of children aged < 5 years (and especially children < 6 months) and adults > 50 years of age.

Which vaccine should be used?

  • The 2008--09 trivalent vaccine virus strains are A/Brisbane/59/2007 (H1N1)-like, A/Brisbane/10/2007 (H3N2)-like, and B/Florida/4/2006-like antigens.
  • Either trivalent inactivated vaccine (TIV) or live attenuated influenza vaccine (LAIV) can be used when vaccinating healthy persons aged 2--49 years.
  • LAIV is licensed for use among nonpregnant persons aged 2--49 years; safety has not been established in persons with underlying medical conditions that confer a higher risk of influenza complications. TIV is licensed for use among persons aged > 6 months, including those who are healthy and those with chronic medical conditions.
  • LAIV should not be administered to children aged <5 years with possible reactive airways disease, such as those who have had recurrent wheezing or a recent wheezing episode. Children with possible reactive airways disease, persons at higher risk for influenza complications because of underlying medical conditions, children aged 6--23 months, and persons aged >49 years should receive TIV.
  • Healthy HCP and persons aged 2--49 years who are contacts of persons in these groups and who are not contacts of severely immunosuppressed persons should receive either LAIV or TIV when indicated or requested. All other persons, including pregnant women, should receive TIV.
  • TIV is preferred for vaccinating household members, HCP, and others who have close contact with severely immunosuppressed persons (e.g., patients with hematopoietic stem cell transplants) during those periods in which the immunosuppressed person requires care in a protective environment (typically defined as a specialized patient-care area with a positive airflow relative to the corridor, high-efficiency particulate air filtration, and frequent air changes).

Is there a danger of viral shedding from LAIV recipients?

  • Available data indicate that both children and adults vaccinated with LAIV can shed vaccine viruses after vaccination, although in lower amounts than occur typically with shedding of wild-type influenza viruses. In rare instances, shed vaccine viruses can be transmitted from vaccine recipients to unvaccinated persons. However, serious illnesses have not been reported among unvaccinated persons who have been infected inadvertently with vaccine viruses.

What should be done if a health care worker has received LAIV?

  • As a precautionary measure, HCP who receive LAIV should avoid providing care for severely immunosuppressed patients for 7 days after vaccination.

What about hospital visitors who have received LAIV?

  • Hospital visitors who have received LAIV should avoid contact with severely immunosuppressed persons in protected environments for 7 days after vaccination but should not be restricted from visiting less severely immunosuppressed patients.

What is recommended regarding vaccination and health care personnel?

  • All HCP, as well as those in training for health-care professions, should be vaccinated annually against influenza (TIV is preferred). Persons working in health-care settings who should be vaccinated include physicians, nurses, and other workers in both hospital and outpatient-care settings, medical emergency-response workers (e.g., paramedics and emergency medical technicians), employees of nursing home and chronic-care facilities who have contact with patients or residents, and students in these professions who will have contact with patients.
  • Health-care administrators should consider the level of vaccination coverage among HCP to be one measure of a patient safety quality program and consider obtaining signed declinations from personnel who decline influenza vaccination for reasons other than medical contraindications. Influenza vaccination rates among HCP within facilities should be regularly measured and reported, and ward-, unit-, and specialty-specific coverage rates should be provided to staff and administration.
  • The Infectious Diseases Society of America has recommended mandatory vaccination for HCP, with a provision for declination of vaccination for religious or medical reasons.

Table 2 and Figure 1