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Get the flu vaccine for the 2023-24 flu season

It’s that time of year again, the influenza season is getting close, and it is time to discuss the full vaccine. I know many of you ignore this particular vaccine with all kinds of lame excuses, but the flu is a dangerous disease, even for people who are young and healthy.

This article will describe how the vaccine works, how it is developed, and what the choices are in the USA (although it will be similar for most countries in the northern hemisphere).

girl getting vaccinated
Photo by CDC on

Flu vaccine boosts the immune system

From year to year, there are variations in the effectiveness of the flu vaccine, although getting the flu vaccine is infinitely better than contracting the flu and risking some of the major complications of the disease.

I think it’s important that vaccine manufacturers start to examine methods on how to improve effectiveness, since the flu, despite the claims of the antivaccine world, is a serious and dangerous disease. And some strains of flu, like the H1N1 can be harmful to young healthy adults.

Without getting too complicated, the flu vaccine induces a systemic immune response to a part of the influenza virus called hemagglutinin, which is a glycoprotein found on the surface of influenza viruses. Both inactivated and live influenza vaccines induce virus-specific serum antibodies which can protect against infection with wild influenza virus possessing the same hemagglutinin antigen.

Developing the right flu vaccine each year

The reason that we don’t have permanent immunity to the flu each season is that each flu season brings new mutations of the hemagglutinin molecule, so the immune system doesn’t recognize the virus anymore, and you get the flu. It doesn’t matter if you get the flu “naturally” or boost your immune system with a vaccine, you are generally susceptible to the newly mutated flu virus each year.

Of course, this makes it difficult to develop a flu vaccine every year, because national health organizations, like the US Centers for Disease Control and Prevention, have to scientifically predict which mutated viruses might be prevalent in the upcoming flu season.

Furthermore, vaccine manufacturers require a six-month lead time from choosing the virus to shipping the vaccine, scientists must quickly determine what the new mutated types might be to give the manufacturers ample time to bring out a new flu vaccine.

The first step in the process of getting the vaccine right is that over 100 national influenza centers in 100 countries receive and test virus samples from patients in their countries. These centers then send samples of the most prevalent viruses to five World Health Organization (WHO) Collaborating Centers for Reference and Research on Influenza,  which include the following research organizations:

Twice a year, in February for the Northern Hemisphere and in September for the Southern Hemisphere, WHO gathers the five Collaborating Centers to meet and discuss which flu virus mutations are going to be prevalent.

The key scientists from each of these centers review the results of surveillance, laboratory, and clinical studies, and the availability of vaccine viruses and make recommendations on the composition of the upcoming season’s influenza vaccine. Generally, the group decides on three subtypes of the flu virus – H1N1 (a subtype of the A flu), H3N2 (another subtype of the A flu), and type B strains. Recently, a second subtype of the type B flu virus is included in the quadrivalent (four flu types) vaccines.

WHO recommends specific vaccine viruses for inclusion in influenza vaccines; however, each country reviews the data and may modify the viruses in the vaccines for their own country. For example, in the USA, the Food and Drug Administration (FDA) makes the final decision about flu vaccines, with input from the CDC, that will be sold in the USA.

As opposed to some of the tropes of the anti-vaxxers, this isn’t random guessing, like throwing darts at influenza strains and saying, “we’re including that flu strain.” In fact, it is a logical, scientific process that includes some of the leading experts on the flu virus from across the world. Although the process is far from perfect, for example, it’s difficult to predict a new mutation that might appear after the February or September meetings, but it works well enough in most years.

In the 2022-23 flu season for the Northern Hemisphere, the CDC estimated that the vaccine was about 71% protective of pediatric patients and 54% of adults against related hospitalization. I realize that’s far from perfect, but given the significant complications and costs of a flu infection, even reducing the risk by half has an important benefit to humans. Furthermore, given the very low risks of the vaccine, the benefit-to-cost equation is overwhelmingly on the side of benefit.

Flu vaccines in the USA

I’m just going to list out the various flu vaccines that will be available in the USA, but mostly the same or similar vaccines are available throughout the Northern Hemisphere.

Six months and older:

Afluria is an inactivated quadrivalent influenza vaccine for active immunization against influenza disease caused by subtypes A and B.

Fluarix is prepared from influenza viruses propagated in embryonated chicken eggs.

Flulaval is a quadrivalent, split-virion, inactivated influenza vaccine from a virus propagated in the allantoic cavity of embryonated hens’ eggs.

Fluzone Quadrivalent is an inactivated vaccine that prevents influenza disease caused by influenza A subtype viruses and type B viruses.

Two-49 years of age:

FluMist is an Intranasal, live quadrivalent vaccine containing four vaccine virus strains. This vaccine is very popular for those individuals who have a fear of needles that are used for other flu vaccines.

Flucelvax is a cell culture-based flu vaccine to help protect against four flu virus strains. 

Eighteen years and older:

Flublok is made without the use of eggs. Therefore, it is not subject to the mutations that are sometimes introduced into the vaccine during egg adaptation that can cause the traditional vaccines to be ineffective. In addition, Flublok contains three times the antigen of standard-dose inactivated influenza vaccines. Flublok is highly purified and does not contain influenza virus, antibiotics, formaldehyde, preservatives, egg protein, latex, gluten, or gelatin, unlike other flu vaccines. It is especially effective in older adults because it has more antigens.


Flu vaccines are starting to ship right now to healthcare providers, so it might be time for you to schedule your flu vaccine. For some of you who are teachers or others who encounter a lot of people (unmasked these days), you should get the vaccine as soon as possible since it takes up to two weeks before you have full immunity.

And remember most of the myths about the flu vaccine are completely false. It cannot cause the flu. You do not have a “natural immunity” to the flu. It does not contain nanobots. And it does not contain “mercury.”

Get the flu vaccine. It saves lives.


Michael Simpson

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