It’s Time for Your Flu Shot

Q:           When is the best time to get a flu shot?

The CDC recommends those aged 65 and older get vaccinated in September or October rather than earlier. There is no “late” cutoff; you can be vaccinated anytime during flu season.

Young children aged 6 months through 8 years getting the flu vaccine for the first time should get 2 doses. Their first dose should be given as soon as the vaccine is available, and the second one 4 weeks later.

Q:           How long does it take to be protected against the flu after vaccination?

It takes about 2 weeks for a flu shot to become fully effective.

Q:           Will a flu shot last you the entire flu season?

Your best protection from the influenza vaccine lasts for about 6 months. Usually, it decreases to 50% of your original protection by 12 months. One vaccination protects the entire flu season if you are young and healthy. 

Q:           Why do we need yearly vaccinations against influenza?

The influenza virus frequently mutates, making your antibodies against influenza less effective.

As the influenza virus reproduces itself, it occasionally makes mistakes. Sometimes, the influenza virus will combine with another flu strain, creating a new one. If the new strain changes enough, we become more susceptible to it.

Q:           Is this year’s flu vaccine the same as last year's?

No. Most human influenza is caused by one of two main types: an A strain or a B strain. Influenza A strains are associated with pandemics and cause more severe symptoms and deaths than B strains.

The World Health Organization (WHO) keeps track of influenza patterns worldwide with facilities in Tokyo, Beijing, Melbourne, London, and Atlanta. They meet each February to decide on the 4 strains best suited for the next influenza vaccine, choosing two A and two B strains.

All influenza vaccines available in the United States are quadrivalent, containing two "A" and two “B” strains.

Last year’s flu vaccine replaced one A strain and one B strain to more closely resemble what people were exposed to. One A strain was updated in the 2023-24 flu formulation.  

Q:           My pharmacy is advertising the “high dose” flu shot. Should I get it? 

Older adults have weaker immune systems and may get only half of the protection of influenza vaccines compared to younger people. This year, there is another option for flu vaccine for older adults.

The FDA approved three influenza vaccine formulations for people 65 years and older. Recent evidence shows that older adults vaccinated with one of these formulas are less likely to be hospitalized from complications from influenza than standard influenza vaccine formulations. These over 65 influenza vaccines boost effectiveness by 24%-36% compared to vaccination with other common influenza vaccines.

Fluzone HD, the "high dose" vaccine, is the most common over-65 flu vaccine available. It contains 4 times the concentration of the standard formulas. Fluad®, a second vaccine option for older adults, includes a usual vaccine dose plus an additive designed to trigger a more robust immune response called an adjuvant. 

The CDC included a third flu vaccine option for people over 65 for the 2023-24 flu season. Flublok® uses recombinant technology instead of egg cultures or mammalian cells to grow flu vaccine. Flublok® is faster to produce than vaccines using egg culture and is safe for those with severe egg or chicken allergies. If interested, check for the availability of Flublok® at your pharmacy.

Q:           What about the “nose spray” flu vaccine?

FluMist® is a nasal influenza vaccine approved for people from 2 to 49 years old. FluMist® contains a live influenza virus and should be AVOIDED by pregnant women, people taking immunosuppressant medication, and anyone taking an antiviral drug within the previous 48 hours.

Q:           Can I get other vaccines with flu vaccine at the same time?

Yes, with three exceptions. The nasal spray vaccine Flumist® contains live virus, so you should wait 2 weeks between getting COVID and Flumist® vaccinations.

Some COVID-19 vaccines and one of the new adult RSV vaccines contain an adjuvant. It is unclear whether there is an increased risk of side effects when receiving more than one vaccine containing adjuvants at a time, such as Fluad®, Shingrix®, or the RSV vaccine Arexvy®.

Q:           What if you are pregnant?

Pregnancy causes changes in your immune system and other organs in the body, making you more likely to suffer severe illness from having influenza. Vaccination against flu can reduce the risk of a pregnant woman being hospitalized with flu by about 40 percent.

Dr. Louise Achey, Doctor of Pharmacy, is a 43-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Get clear answers to your medication questions at her website and blog, TheMedicationInsider.com.

©2023 Louise Achey