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Timing of Vaccination Vaccination efforts should be structured to ensure the vaccination of as many persons as possible over the course of several months, with emphasis on vaccinating as many persons as possible before influenza activity in the community begins. Even if vaccine distribution begins before October, distribution probably will not be completed until December or January. The following recommendations reflect this phased distribution of vaccine. In any given year, the optimal time to vaccinate patients cannot be determined because influenza seasons vary in their timing and duration, and more than one outbreak might occur in a single community in a single year. In the United States, localized outbreaks that indicate the start of seasonal influenza activity can occur as early as October. However, in >80% of influenza seasons since 1976, peak influenza activity (which is often close to the midpoint of influenza activity for the season) has not occurred until January or later, and in >60% of seasons, the peak was in February or later (Table 1). In general, health-care providers should begin offering vaccination soon after vaccine becomes available and if possible by October. To avoid missed opportunities for vaccination, providers should offer vaccination during routine health-care visits or during hospitalizations whenever vaccine is available. Vaccination efforts should continue throughout the season, because the duration of the influenza season varies, and influenza might not appear in certain communities until February or March. Providers should offer influenza vaccine routinely, and organized vaccination campaigns should continue throughout the influenza season, including after influenza activity has begun in the community. Vaccine administered in December or later, even if influenza activity has already begun, is likely to be beneficial in the majority of influenza seasons. The majority of adults have antibody protection against influenza virus infection within 2 weeks after vaccination (337,338). Children aged 6 months-8 years who have not been vaccinated previously or who were vaccinated for the first time during the previous season and received only 1 dose should receive 2 doses of vaccine. These children should receive their first dose as soon after vaccine becomes available as is feasible, so both doses can be administered before the onset of influenza activity. Persons and institutions planning substantial
organized vaccination campaigns (e.g., health departments,
occupational health clinics, and community vaccinators) should
consider scheduling these events after at least mid-October because
the availability of vaccine in any location cannot be ensured
consistently in early fall. Scheduling campaigns after mid-October
will minimize the need for cancellations because vaccine is
unavailable. These vaccination clinics should be scheduled through
December, and later if feasible, with attention to settings that
serve children aged 6-59 months, pregnant women, other persons aged
<50 years at increased risk for influenza-related complications,
persons aged >50 years, HCP, and persons who are household contacts
of children aged <59 months or other persons at high risk. Planners
are encouraged to develop the capacity and flexibility to schedule
at least one vaccination clinic in December. Guidelines for planning
large-scale immunization clinics are available at
http://www.cdc.gov/flu/professionals/ During a vaccine shortage or delay, substantial proportions of TIV doses may not be released and distributed until November and December, or later. When the vaccine is substantially delayed or disease activity has not subsided, agencies should consider offering vaccination clinics into January and beyond as long as vaccine supplies are available. Campaigns using LAIV also may extend into January and beyond. |