Is it recommended to receive an influenza (flu) vaccination in May?

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Last updated: May 2, 2025View editorial policy

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From the Guidelines

Getting a flu shot in May is generally not recommended in the Northern Hemisphere, as flu season typically runs from October to April. The ideal time to get your annual flu vaccine is in September or October, before the flu season begins, as recommended by the AAP and CDC 1. This timing allows your body to develop immunity before flu viruses start circulating widely. Flu vaccines provide protection for about 6-8 months, so getting vaccinated in May would mean your immunity might wane before the peak of the next flu season. However, there are some exceptions to consider:

  • If you're traveling to the Southern Hemisphere (where flu season runs from April to September), you should consider getting a flu shot in May, preferably at least 2 weeks before departure, to reduce your risk for influenza 1.
  • If you have missed the previous season's vaccination, or have a specific medical recommendation, getting a flu shot in May might be appropriate. It's essential to note that immunity after influenza vaccination can wane over time, and studies suggest that very early vaccination (July or August) might be associated with suboptimal immunity before the end of the influenza season 1. Therefore, for optimal protection against seasonal influenza, it's crucial to align your vaccination timing with the start of your region's flu season.

From the Research

Flu Shot in May

  • The flu season typically begins in October, and vaccination is recommended at the beginning of the flu season 2.
  • It takes approximately 14 days after vaccination for a healthy adult to reach peak antibody protection 2.
  • There is no specific information in the provided studies about getting a flu shot in May, but it is generally recommended to get vaccinated against influenza before the start of the flu season.
  • The studies focus on the effectiveness of different types of influenza vaccines, such as high-dose and adjuvanted vaccines, in preventing influenza-like illness and hospitalizations 3, 4, 5.
  • The Advisory Committee on Immunization Practices (ACIP) recommends routine annual influenza vaccination for all persons aged ≥6 months who do not have contraindications, and vaccination should occur as soon as possible after vaccine becomes available 6.
  • However, for nonpregnant adults, vaccination in July and August should be avoided unless there is concern that later vaccination might not be possible 6.

Key Points

  • Flu season typically starts in October.
  • Vaccination is recommended at the beginning of the flu season.
  • Peak antibody protection is reached approximately 14 days after vaccination.
  • No specific information is available about getting a flu shot in May.
  • Different types of influenza vaccines have been studied for their effectiveness in preventing influenza-like illness and hospitalizations 3, 4, 5.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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