In the book Alice’s Adventures in Wonderland, the Red Queen said to Alice: “My dear, here we must run as fast as we can, just to stay in place. And if you wish to go anywhere you must run twice as fast as that.” [1]
What does this have to do with biology and vaccines? The Red Queen’s metaphor is typically used when talking about extinction and survival – how each species is constantly changing and putting pressure on the competitor to keep up with them. In the context of vaccines, although the Red Queen’s metaphor is not perfect, it illustrates an important point – for some viruses*, researchers need to continuously develop new vaccines with small modifications. For example, the CDC recommends that people get the flu vaccine every year [2] for two reasons: the immune protection may decrease over time, and the flu virus is constantly mutating itself.
While some vaccines lead to several years of immunity**, other vaccines (like the flu shot) require boosters and annual vaccination. The flu virus is constantly mutating, in order words, it is changing its genetic material. These mutations lead to a random “antigenic drift”, where the virus alters its surface. By changing its appearance, the virus could stop being recognized by the immune system. It is much like a race – the virus is “running” to change itself and become undetectable to the immune system. In turn, we need to “run” as well – we must get vaccinated for the modified virus. These new vaccines will teach our immune system once again how to defend against the mutated virus (for more information, check out this text). Each following year, the race continues. The virus has changed again, and we need new vaccines.
Researchers use surveillance reports to predict the most common influenza virus that will circulate during the following season [3] and will develop the vaccine based on this. Since several flu strains could be circulating, researchers can actually create a vaccine that counters several strains. For example, a trivalent and quadrivalent vaccine can provide protection against three or four flu viruses, respectively [4]. The effectiveness of the vaccine will depend on the similarities between the vaccine and the circulating virus [4].
Annual vaccinations are recommended [2] because they are the best armor against the continuously evolving flu viruses. In the meantime, scientists are trying to discover how to make us “run” faster in this race against influenza. Still, vaccination effectiveness can depend on each person’s health. If you have allergies to eggs or to a vaccine component, or if you have had Guillain-Barré Syndrome, please talk to your physician before vaccination to decide whether the flu shot is appropriate in your case [5].
*Virus - it can be considered a very small and basic life form or an aggregate of molecules that is simpler than a cell. They can be found in the environment or inside living organisms. It has to infect a cell and use its machinery to multiply, since it cannot multiply by itself. Viruses consist of nucleic acids (DNA or RNA), a protein capsid that contains the nucleic acids and, sometimes, an external envelope of lipids. The flu, measles, AIDS and Covid-19, for instance, are caused by viruses.
*Immunity - an established memory and quick response that our bodies have against infection by pathogens or foreign molecules that enter our bodies. When we combat and survive an infection, we normally develop resistance against the organism or molecule that caused the infection. Vaccines train our bodies to develop immunity against pathogens, without the need to be infected by them first.
————————————-
Written by: Nicole
Edited by: María and Natasha
BioDecoded is a volunteer group committed to sharing accurate scientific information. If you have any questions about this topic, please comment or send them to our email.
References:
A quote from Alice in Wonderland. Goodreads Available at: https://www.goodreads.com/quotes/458856-my-dear-here-we-must-run-as-fast-as-we. (Accessed: 2nd June 2021)
Key Facts About Seasonal Flu Vaccine. Centers for Disease Control and Prevention (2021). Available at: https://www.cdc.gov/flu/prevent/keyfacts.htm. (Accessed: 2nd June 2021)
Selecting Viruses for the Seasonal Influenza Vaccine. Centers for Disease Control and Prevention (2021). Available at: https://www.cdc.gov/flu/prevent/vaccine-selection.htm. (Accessed: 2nd June 2021)
Vaccine Effectiveness: How Well Do the Flu Vaccines Work? Centers for Disease Control and Prevention (2021). Available at: https://www.cdc.gov/flu/vaccines-work/vaccineeffect.htm. (Accessed: 2nd June 2021)
Who Should and Who Should NOT Get a Flu Vaccine. Centers for Disease Control and Prevention (2021). Available at: https://www.cdc.gov/flu/prevent/whoshouldvax.htm. (Accessed: 3rd June 2021)
Comments