From the Guidelines
The administration of the influenza vaccine should not be discontinued until June 30 of each year, as the influenza season is unpredictable and protective immune responses persist throughout the season. This recommendation is based on the most recent and highest quality study available, which suggests that vaccination efforts should continue throughout the season because the duration of the influenza season varies, and influenza activity might not occur in certain communities until February or March 1. The rationale for continued vaccination is that influenza activity often peaks between December and February but can extend into May, and it takes approximately two weeks after vaccination for antibodies to develop and provide protection.
Some key points to consider when administering the influenza vaccine include:
- Vaccination should continue to be offered as long as influenza viruses are circulating in the community and unexpired vaccine is available
- Even late vaccination in January or beyond can still provide protection during the remaining influenza season, which can last until May in some years
- This recommendation applies to all approved influenza vaccine formulations, including standard-dose, high-dose, adjuvanted, and recombinant vaccines
- Healthcare providers should use clinical judgment based on local influenza activity patterns and continue vaccinating patients until the season ends or vaccine supplies are depleted
It's also important to note that the influenza season can be unpredictable, and peak activity has not occurred until January or later in 58% of seasons, with some seasons having more than one disease peak 1. Additionally, some studies have reported decreases in vaccine effectiveness within a single influenza season, with increasing time post-vaccination, although this effect is not consistently observed across age groups, virus subtypes, and seasons 1.
Overall, the key takeaway is that vaccination efforts should continue throughout the influenza season, and healthcare providers should not discontinue administration of the influenza vaccine until June 30 of each year. This approach will help to optimize vaccination coverage and provide protection against influenza throughout the entire season 1.
From the Research
Influenza Vaccine Administration
The provided studies do not directly address when the administration of the influenza vaccine should be discontinued each season. However, they do provide information on the timing of influenza vaccination.
- The influenza season typically begins in October, and vaccination should occur at the beginning of the flu season 2.
- Vaccination soon after the vaccine becomes available can be considered for pregnant women in the third trimester 3.
- Children who need 2 doses should receive their first dose as soon as possible after the vaccine becomes available to allow the second dose to be received by the end of October 3.
- For nonpregnant adults, vaccination in July and August should be avoided unless there is concern that later vaccination might not be possible 3.
Vaccine Effectiveness and Duration
The effectiveness of the influenza vaccine can vary from season to season due to factors such as antigenic drift and shift 2.
- It takes approximately 14 days after vaccination for a healthy adult to reach peak antibody protection 2.
- The duration of protection provided by the influenza vaccine is not explicitly stated in the provided studies.
Recommendations for Influenza Vaccination
The Advisory Committee on Immunization Practices (ACIP) recommends routine annual influenza vaccination for all persons aged ≥6 months who do not have contraindications 3.