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Notice to Readers: Delayed Supply of Influenza Vaccine and Adjunct ACIP Influenza Vaccine Recommendations for the 2000--01 Influenza Season

Annual vaccination against influenza is the primary means for minimizing serious adverse outcomes from influenza virus infections. These infections result in approximately 20,000 deaths and 110,000 hospitalizations per year in the United States (1). The amount of trivalent inactivated influenza vaccine produced for distribution in the United States has increased substantially; in 1999, four manufacturers produced a combined total of 80 to 85 million doses.

For the 2000--01 influenza season in the United States, lower than anticipated production yields for this year's influenza A(H3N2) vaccine component and other manufacturing problems are expected to lead to a substantial delay in the distribution of influenza vaccine and possibly substantially fewer total doses of vaccine for distribution than last year. A more precise estimate of the vaccine supply will be available as production progresses during the summer. Because many vaccine providers currently are planning their fall vaccination activities, CDC and the Advisory Committee on Immunization Practices (ACIP) are issuing adjunct influenza vaccination recommendations beyond those made by ACIP on April 14, 2000 (1). The adjunct recommendations are specific to the 2000--01 influenza season.

Adjunct Influenza Vaccine Use Recommendations for the 2000--01 Influenza Season

  1. Implementation of organized influenza vaccination campaigns should be delayed. Health-care providers, health organizations, commercial companies, and other organizations planning organized influenza vaccination campaigns for the 2000--01 influenza season should delay vaccination campaigns until early to mid-November. The purpose of this recommendation is to minimize cancellations of vaccine campaigns and wastage of vaccine doses resulting from delays in vaccine delivery.
  2. Influenza vaccination of persons at high risk for complications from influenza and their close contacts should proceed routinely during regular health-care visits. Routine influenza vaccination activities in clinics, offices, hospitals, nursing homes, and other health-care settings (especially vaccination of persons at high risk for complications from influenza, health-care staff, and other persons in close contact with persons at high risk for complications from influenza) should proceed as normal with available vaccine.
  3. Provider-specific contingency plans for an influenza vaccine shortage should be developed. All influenza vaccine providers, including health-care systems and organizers of vaccination campaigns, should develop a provider-specific contingency plan to maximize vaccination of high-risk persons and health-care workers. These plans should be available for implementation if a vaccine shortage develops.

Use of Influenza Antiviral Medications

There are no new recommendations for the use of influenza antiviral drugs. The approved usage (i.e., for treatment or chemoprophylaxis), age group, dosage, route of administration, metabolism, and adverse reactions of these agents vary (1), and all of them require prescription by a physician. Influenza antiviral drugs are useful for controlling influenza outbreaks in specific and circumscribed situations, such as nursing homes. In addition, long-term antiviral chemoprophylaxis of high-risk institutionalized residents or some persons at high risk for complications from influenza might be indicated if vaccine either is unavailable, ineffective (e.g., severely immunocompromised persons), or contraindicated.

However, these drugs are not a substitute for influenza vaccine. Even if an influenza vaccine shortage develops, CDC and ACIP do not support their routine and widespread use as chemoprophylaxis against influenza because this is an untested and expensive strategy that could result in large numbers of persons experiencing adverse effects.

Additional Discussion

In the United States, 70 to 76 million persons (approximately 35 million persons aged >65 years; 33 to 39 million persons aged <65 years with high-risk medical conditions; and 2 million pregnant women) are at high risk for serious complications from influenza infections, including hospitalizations and deaths. The expected delay in influenza vaccine distribution and a possible shortage for the 2000--01 influenza season has raised difficult questions of how to maximize protection against influenza for these persons. One complicating factor is that many vaccine providers must plan their fall vaccination activities now even though the vaccine supply is uncertain. Given the current situation, CDC and ACIP have issued modified recommendations for the 2000--01 season emphasizing the delay of organized influenza vaccine campaigns until November, the continuation of routine vaccination activities during regular health-care visits, and the development of provider-specific contingency plans in case a vaccine shortage should develop. There are additional important points worth emphasizing in addition to these main recommendations:

  • Influenza vaccine administered after mid-November can still provide substantial protective benefits. In general, ACIP recommends that routine vaccination of persons at high risk for complications from influenza begin in September. In previous years, ACIP has recommended that organized campaigns take place during October through mid-November. These timing recommendations balance several considerations, including the desirability of administering vaccine before substantial seasonal influenza activity has begun but not vaccinating so early such that vaccine antibody titers might substantially decrease in some persons. Nonetheless, many persons who should receive influenza vaccine remain unvaccinated after mid-November, and for many of these persons, influenza vaccination after mid-November will be beneficial. For the 2000--01 season, it is particularly important for vaccine providers to continue to administer vaccine after mid-November.
  • Once vaccine is available, health-care workers should provide vaccine to persons at high risk for complications from influenza as is normally done. This is particularly important for young children at high risk who are receiving influenza vaccination for the first time and who require two doses of vaccine.
  • Minimizing wastage of influenza vaccine is important. In particular, influenza vaccine purchasers should refrain from placing duplicate orders with multiple companies to minimize the amount of vaccine that is returned to a manufacturer and discarded. Options to promote redistribution of vaccine that otherwise would be returned or discarded are being developed.
  • In 2000, ACIP broadened its influenza vaccine recommendations to include all persons aged 50--64 years. This recommendation was based, in part, on an effort to increase vaccination coverage of persons in this age group with high-risk conditions. In the context of a possible vaccine shortage, it would be appropriate for contingency plans covering this age group to focus primarily on vaccinating persons with high-risk conditions rather than this entire age group.
  • Influenza vaccine is routinely recommended for persons in close contact with persons at high risk for complications from influenza because such persons are in a position to transmit influenza virus infection to high-risk persons. Vaccination of health-care workers has been highlighted in particular because health-care workers have frequent and close contact with many different high-risk persons at a time when high-risk persons are particularly vulnerable.

As new information becomes available, CDC and the Food and Drug Administration (FDA) will issue updates. In the meantime, ACIP and CDC request that persons and organizations planning to administer influenza vaccine, as well as members of the general public, join in these efforts to maximize protection of persons most likely to develop serious and life-threatening complications from influenza. FDA, CDC, ACIP, National Institutes of Health, and vaccine manufacturers will continue to work together to facilitate the availability of influenza vaccine for the upcoming season and to minimize the adverse impact of an influenza vaccine shortage if one should develop. If a substantial vaccine shortage appears imminent, or if the situation warrants, then CDC and ACIP will issue further recommendations.


  1. CDC. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2000;49(no. RR-3).

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