Cate Roser, Illustrator

As part of the Yale Community Compact for the 2022-2023 school year, all Yale undergraduate, graduate and professional students are required to get their flu shot this fall. 

According to the Centers for Disease Control and Prevention flu shots can not only prevent one from getting sick with the flu, but also reduce severity of illness and risk of hospitalization. They currently recommend flu shots for everyone 6 months and older, with exceptions for those with life-threatening allergies to any ingredient in the vaccine or those who have had a severe allergic reaction to flu shots in the past. 

James Meek, an associate director of the Yale Emerging Infections Program, explained in an email to the News that flu shots work by preparing our immune system for exposure to the virus. 

“The influenza vaccine causes the immune system to create antibodies [that] about two weeks after vaccination, will protect against influenza illness,” Meek wrote. “Essentially, our immune system is being primed by the vaccine to recognize the proteins on the outside of the influenza virus as foreign and something that needs to be eliminated.”

Meek continues to explain that there are two primary types of influenza, type A and type B, as well as different strains within these two types. The flu vaccine needs to be modified every year based on which strains are predicted to be dominant. 

To do this, global surveillance data from the previous flu season is used by the World Health Organization and the US Food and Drug Administration to make a decision as to whether last year’s flu shot must be modified to be effective against next year’s strain. This year, the vaccines are quadrivalent, meaning that they offer protection against two strains of influenza A and two strains of influenza B. 

According to Paul Genecin, the chief executive officer of Yale Health and an associate clinical professor of medicine, the efficacy of the flu shot will vary depending on how accurate predictions were about the dominant circulating flu strain. However, Genecin emphasized that fear of inaccurate predictions should not discourage people from getting their shot. 

“When there are mismatches between the circulating flu strains and the antigens in the vaccine, the vaccine has decreased efficacy in preventing infection, but the vaccines nevertheless protect against severe illness,” Genecin wrote. “Even in years with significant mismatch of antigens, the benefits of reducing severity, hospitalization and death are significant. The possibility of vaccine mismatch is never a reason to avoid vaccination.”

According to Meek, flu shots are especially important this year. Since less COVID-19 mitigation measures are currently being implemented, chances of influenza exposure have increased drastically from the past two years, and natural immunity to influenza in the population has likely decreased as well. 

Douglas Shenson, an associate professor at the Yale School of Medicine and an associate clinical professor at the Yale School of Public Health, explained another little known benefit of the flu shot – that it may also be indirectly beneficial if a patient is infected with COVID-19 at some point. 

“COVID and influenza virus, while dissimilar in their characteristics, represent a two-fold threat to the respiratory system of those who are not fully vaccinated,” Shenson wrote. “That is, infection with one of these viruses may make the other more injurious. It is therefore important to get vaccinated against both viruses, thereby protecting oneself and others. There is already evidence that very sick COVID-infected patients on mechanical ventilators do significantly better if they have previously been vaccinated against influenza.”

Meek, Genecin and Shenson all emphasized that influenza leads to hundreds of thousands infections annually, which can place a burden on healthcare systems. Therefore, getting the flu shot has been crucial to mitigating the strain on hospitals throughout the COVID-19 pandemic.

“With so much respiratory illness due to COVID-19 and other pathogens going around, we need to do everything possible to minimize the complexity of diagnostic workups and overload in our healthcare facilities including hospitals,” Genecin wrote. “Remember that influenza is a major contributor to overcrowded hospitals – a serious concern as the COVID pandemic continues to drive hospital and ICU admissions.”

Genecin said that those in the northern hemisphere should aim to be vaccinated in September or October, although those who are contemplating getting the vaccine later in the winter should not hesitate to get it then.

Shenson reassured anyone that is hesitant to get a flu shot that there is substantial proof that the benefits outweigh the risks.

“Getting a flu shot should give you peace of mind,” Shenson wrote. “The vaccination is provided to a great many people and so we know it is safe. On the other hand, we have equally strong evidence the disease it protects against can be dangerous. The best move is to get vaccinated.”

Yale Health is currently offering free flu shots on an appointment basis for all Yale Health members, Yale students and Yale employees. Students can schedule their appointments through the Yale Flu Shot Finder.

Flu shots received through Yale Health will automatically be uploaded to one’s Yale Health records; students who receive their shot through an outside clinic must record their vaccine date and provider through Yale’s external flu attestation form.