Aug 27, 2019
Ronne asked
I am 73 yrs old and in fairly good health. I get a flu shot every year and I haven't had the flu in 25 yrs! How early in the flu season should I get the flu shot? I usually get it around the middle of September. Is this ideal or should I get it earlier?
At a glance
- A number of studies report that the efficacy of the flu vaccine decreases over time (within a single season).
- The CDC (Centers for Disease Control) and ACIP (Advisory Committee on Immunization Practices) do acknowlege that effectiveness may decrease over time, but that must be weighed against missed vaccination opportunities and other factors (e.g. early flu seasons).
- Overall, the recommendation by the CDC is to get the flu vaccine by the end of October, but it is still beneficial to receive it before (or after) that time if necessary.
Answer
This is a great question and, unfortunately, the answer is a bit muddled.
To start, a number of clinical studies report that the effectiveness of the flu vaccine does decrease over time during a single flu season.
For example, one study, published in Clinical Infectious Diseases, concluded the following:
References
- Waning of influenza vaccine protection: Exploring the trade-offs of changes in vaccination timing among older adults. PubMed
- Key Facts About Seasonal Flu Vaccine. CDC
- Intraseason Waning of Influenza Vaccine Protection: Evidence From the US Influenza Vaccine Effectiveness Network, 2011–2012 Through 2014–2015. Oxford Academic
- Waning vaccine protection against influenza A (H3N2) illness in children and older adults during a single season. ScienceDirect
- Is It Possible to Get a Flu Shot Too Early? JAMA Network
- Intraseason Waning of Influenza Vaccine Protection: Evidence From the US Influenza Vaccine Effectiveness Network, 2011–2012 Through 2014–2015. Oxford Academic
- Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2019–20 Influenza Season. CDC
- Seasonal Influenza Vaccine Dosage & Administration Questions & Answers. CDC
