Throughout the past century, many medical advances have been made to combat some of the most devastating diseases known to humankind. Perhaps one of the most significant innovations in recent history is the creation of the vaccine, primarily responsible for saving millions of lives from many debilitating viral illnesses.
The influenza virus vaccine can prevent many people from acquiring influenza infection during the winter season each year. Despite this fact, there remains an atmosphere of uncertainty and doubt among many people in the United States regarding the vaccine’s safety and efficacy. Therefore, to better understand the reasoning behind such sentiments in the patient population, this article explores various studies evaluating patient perceptions toward the influenza vaccine, so that ultimately primary care clinicians can help identify the specific concerns their patients may have about influenza vaccination, inform them of the current scientific data detailing the importance of this vaccine, and successfully encourage patients to get vaccinated in order to protect themselves and others from a potentially devastating illness.
Overview: Influenza and the influenza vaccine
Over the course of history, influenza has become infamous for its multiple pandemics affecting millions worldwide, from the “Spanish Flu” outbreak in the early 20th century, to the first “Avian Flu” outbreak in 2003, to the first “Swine Flu” outbreak in 2009.1,2 The symptoms of influenza virus infection can vary and may include fever, cough, general fatigue, and body aches, which may last from 3 to 7 days (Table 1).3-5 However, those who are more susceptible to influenza virus infection, including young children, the elderly, and the immunocompromised, may have more severe symptoms with a higher risk of complications from the disease, including death.3,4 Furthermore, someone infected with the influenza virus may acquire a bacterial superinfection as a result of his or her acute immunocompromised state, often presenting as pneumonia or otitis media; other complications of influenza infection include myositis, cardiac pathologies (eg, myocarditis), and toxic shock syndrome.4,5
The influenza vaccine has the capacity to significantly counter many of the symptoms that accompany the illness and is thus recognized as the most effective strategy for preventing seasonal influenza virus infection if given each year.5,6 Due to the ever-changing morphology and genetic make-up of the influenza virus, known as “antigenic drift” if minor (an epidemic), or rarely, an “antigenic shift” if major (a pandemic), the medical community creates a new vaccine each year that reflects which influenza subtypes are particularly prominent in the region, with the ultimate hope that the vaccine will prevent the population from contracting these particular subtypes.4
To ensure that the vaccine can be used in all age groups and in those with certain medical conditions, multiple types of influenza vaccine are available for administration: the inactivated influenza vaccine, the live attenuated intranasal vaccine, and the recombinant influenza vaccine are examples of such. Of these three options, inactivated influenza vaccine is the most popular, as it can prevent influenza virus infection up to 65% of the time. However, for those with egg allergies, the recombinant influenza vaccine is most suitable, as this vaccine is made using cultured animal cells instead of fertilized eggs. Furthermore, to ensure that individuals are protected against different influenza subtypes, both the trivalent (covering 3 different subtypes of influenza virus) and the quadrivalent (covering 4 different subtypes of influenza virus) vaccines are available for use. Due to increased protection against the various influenza strains, the CDC recommends administration of the quadrivalent vaccine over the trivalent vaccine to individuals without contraindications for receiving this vaccine type. For those aged 65 years and older, a more potent vaccination option induces a stronger immune response against influenza in comparison to the regular flu shot.
However, for those with egg allergies, the recombinant influenza vaccine is most suitable, as this vaccine is made using cultured animal cells instead of fertilized chicken eggs.6 Common side effects with vaccination against influenza infection include fever, fatigue, headache, and joint pain, which usually resolve within a week; though cases are much more rare, Guillain-Barré syndrome, a disorder affecting the peripheral nervous system that may result in paralysis, has also been associated with administration of the influenza vaccine (Table 2).5