Influenza Vaccine


Article Author:
Saieda Kalarikkal


Article Editor:
Gayatri Jaishankar


Editors In Chief:
Tod Aeby


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Trevor Nezwek
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
5/30/2019 9:12:02 PM

Indications

Influenza viruses belong to Orthomyxoviridae RNA virus family and classify into three distinct types based on their major antigenic differences; influenza A, influenza B and influenza C.  Influenza viruses cause the annual human epidemics, seasonal and pandemic. Seasonal influenza epidemics caused by influenza A and B viruses result in 3–5 million severe cases and thousands of deaths globally each year. Influenza pandemics caused by influenza A virus emerge at unpredictable intervals. The influenza A virus will cause epidemics and pandemics because of its spread from migrating birds, pigs, horses, and humans. Transmission can be human to human from fomites, coughing and sneezing. Pandemics are responsible for increased morbidity and mortality, compared with seasonal influenza. Four such pandemics have occurred in the past century, during 1918, 1957, 1968, and 2009. Influenza B causes only human to human spread with a particular emphasis on the fact that no other hosts are involved, therefore, not involved in pandemics. Influenza C is a mild disease.[1] It causes seasonal episodes of influenza such as Northern infections when they happen from September to March while Southern infections happen from May to September. Due to the variation in viruses responsible for infections in these two seasons; it needs two different sets of vaccines. Influenza generally has an incubation period of 2 days, ranging from 1 to 4 days.  

FDA-approved indications:

  1. Prevention of Influenza A in persons aged 6 months and above
  2. Prevention of Influenza B in persons aged 6 months and above

The Centers for Disease Control and Prevention (CDC) recommends administration of an annual influenza vaccine for all persons above 6 months of age.

The vaccination is the most effective method for prevention and control of influenza. It is most effective in children greater than 2 years old and healthy adults. The efficacy of the seasonal influenza vaccine ranges between 10% and 60%. The lowest efficacy occurs when vaccine strains are not well matched to circulating strains. Both the trivalent and quadrivalent vaccines are FDA approved.[2]

Regarding immunization in pregnancy, a randomized controlled trial conducted in South Africa has shown that when pregnant women receive the influenza vaccine, it halves their risk of developing influenza while reducing the risk of their infants (up to 24 weeks) contracting the illness.[3]

Data shows the trivalent influenza vaccine provides protection in HIV-infected adults without severe immunosuppression while the effectiveness in HIV-infected children aged <5 years is somewhat uncertain. In certain groups, including the elderly, immune-compromised individuals and infants, the influenza vaccine is less effective, but it is beneficial by reducing the incidence of severe disease, like bronchopneumonia, and reduces hospital admission and mortality.[4]

Mechanism of Action

Influenza viruses express two types of antigens; hemagglutinin (HA) and neuraminidase (NA). Influenza A virus has 18 HA, and 11 NA subtypes and these antigens are critical for the virulence of the organism. The trimeric hemagglutinin glycoprotein acts by promoting attachment of the virus to the host cell surface resulting in fusion and thereby releasing virions into the cytoplasm.[1] 

Differently combined H and N antigens are seen in influenza A, that in turn undergo antigenic drifts and shifts resulting in antigenic variation and thereby the necessity for vaccine strain types to vary accordingly. Antigenic drifts are genetic changes occurring in the virus due to various actions of polymerases leading to gradual antigenic changes in both HA and NA producing new variant strains. An antigenic shift takes place when the currently circulating virus disappears and gets replaced by a new subtype with novel glycoproteins to which antibodies against the previously circulating subtype do not cross-react.[5]

Influenza vaccine conveys immunity against the influenza virus by stimulating the production of antibodies specific to the disease. Antibodies to NA act by aggregating viruses on the cell surface effectively and reducing the amount of virus released from infected cells.  Regarding the induction of immunity, the surface HA protein of the influenza virus contains two structural elements, head and stalk wherein the head is the primary target of antibodies that confer protective immunity against influenza viruses.[1]

Flu shots offer protection against three or four strains of the flu virus. Trivalent flu vaccines provide protection against two influenza A strains, H1N1 and H3N2, and one influenza B strain. Quadrivalent flu vaccines protect against the same strains as the trivalent vaccine as well as an additional strain of influenza B.[6]

The mechanism of immune protection is more complicated, as while primarily humoral, cell-mediated immunity also plays an essential role in immunity to influenza. After vaccination, it takes two weeks to build up an immune response against the flu. The effectiveness of a vaccine depends on several host factors such as age, underlying health status, genetic status and furthermore on antigenic matches between the vaccine and circulating viruses.[7]

Administration

Flu shots are available in several forms[8][9][10]:

  • Intramuscular vaccine 
  • High-dose vaccine (> 65 years)
  • Intradermal vaccine (18 to 64years)
  • Egg-free vaccine (>4 years)
  • Nasal spray (2 to 49years)
  • Needle-free vaccine as a jet injector (18 to 64 years)

Dosage:

  • Age 6 months to 3 years;

0.25 - 0.5 ml: 2 doses 4 weeks apart.

  • Age 3 to 8 years:

Not previously vaccinated: 2 doses, 0.5 ml 4 weeks apart.

Vaccinated previous season; 0.5 ml one or two doses 4 weeks apart.

  • Age 9 years and above[11]:

Single dose;  0.5 ml

Adverse Effects

  • Injection site reactions
  • Fever
  • Irritability
  • Drowsiness
  • Myalgia
  • Nasal spray 
    • Upper respiratory symptoms
    • Fever, headache, vomiting
    • Lower respiratory symptoms
  • Rare 
    • Allergic reaction
    • Urticaria/Anaphylaxis

Contraindications

  • History of allergy or hypersensitivity to any component of the vaccine (i.e., egg protein allergy)
  • Infants less than 6 months of age
  • High fever
  • Guillain–Barre Syndrome[12]

Monitoring

CDC and FDA continuously monitor vaccine safety and will inform health officials, health care providers, and the public when necessary.

CDC uses three systems vaccine safety monitoring:

  1. The Vaccine Adverse Event Reporting System (VAERS): an early warning system that helps CDC and FDA monitor problems following vaccination.  Anyone can report possible vaccine side effects to VAERS.
  2. The Vaccine Safety Data link (VSD): a collaborative effort between the CDC and nine other health care organizations, which allows ongoing monitoring and proactive searches of vaccine-related data.
  3. The Clinical Immunization Safety Assessment (CISA) Project: a partnership between CDC and several medical centers that conduct clinical research on vaccine-associated health risks.[13]

Inactivated flu vaccine and pneumococcal vaccine administered at the same time may show an increased risk for febrile seizures.

Toxicity

The vaccine does not manifest any dose-dependent toxicity.

The toxicity regarding carcinogenicity and infertility have undergone extensive study and shown to be negative. 

The components of the influenza vaccine are: 

  • Formaldehyde used to inactivate toxins from viruses and bacteria. 
  • Thimerosal safeguards against contamination, and it is only present in multi-dose vials.
  • Aluminum salts act as adjuvants and impart stronger immune response.
  • Gelatin is present as a stabilizer. 
  • Antibiotics, such as gentamicin or neomycin are present in the flu vaccine to keep bacteria from growing.

Toxicity due to the components of the vaccine is not present due to the inconspicuous amounts in the vaccine.[14][15]

Enhancing Healthcare Team Outcomes

Vaccination is the primary strategy for prevention and control of influenza. The success of the vaccination depends upon the promotion by the health workers, like physicians, nurses, pharmacists, and other health care professionals. A proper understanding of the vaccine benefits is mandatory. Discouraging the vaccination for trivial reasons should be avoided.

Encourage health professionals at risk to vaccinate themselves.

Pregnant women should be protected either by individual vaccination or by cocoon protection by vaccinating the surrounding people. Vaccinating the pregnant women is preferable. Influenza infection after vaccination tends to less severe, and complications also reduced. And it helps to protect the baby against flu during the crucial first six months of life as the mother passes the immune protection to her newborn.[16][3]

The real challenge in the primary strategy for prevention and control of the influenza virus is the antigenic drifts and shifts. Annual vaccination is the current recommendation due to waning immunity.

A Universal influenza vaccine is undergoing trials and serves the purpose of building a single vaccine which targets all strains of the virus; this will, in turn, minimize the need for frequent vaccination and be the bright future of this vaccination.[17][18]


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Influenza Vaccine - Questions

Take a quiz of the questions on this article.

Take Quiz
A patient comes to the outpatient clinic and tells the nurse, "I have never had a flu shot, but I would like to have one this year." What information elicited from the patient would indicate that the influenza virus vaccine should not be given?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
An infant's mother asks you whether her infant should receive an influenza vaccine. Which of the following children are not recommended to receive influenza vaccine?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which patients should not be given an inactivated influenza vaccine?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following immunizations should an elderly patient have yearly?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following patients should not receive the influenza virus vaccine?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What should patients with egg allergies be taught about the flu vaccination?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 65-year old patient presents for an annual health exam. Which of the following is recommended by the US Preventive Services Task Force?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is a recommended annual vaccination for a patient aged 65 years of age and older?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Who is least in need of receiving the influenza vaccination?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following patients should not have inactivated influenza vaccine?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
In the United States, at what time of year should a flu shot be given?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 32-year old female is 4-months pregnant and wants to know if she is eligible for the flu vaccine. Which of the following is the appropriate response?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A mother brings her 5-year old child for the annual influenza vaccine. However, she states the child has an egg allergy with resulting hives. The mother wants to know the risk of the vaccine to the child. What do you tell her?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which influenza virus responsible for pandemic infections?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 17-year-old college student requests advice about influenza vaccination. He mentioned an episode of muscle weakness in the past from which he recovered completely. There is no family history of muscle diseases. On examination, neurological examination was normal. He had a systolic murmur signifying a valvular disorder that was under the care of a cardiologist. Evaluation of other systems was within normal limits. How should the patient be advised?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 9-month-old baby was brought for influenza vaccination. On enquiring the mother gives a history of egg allergy in the infant. What could be the advice regarding vaccination?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What are the modes of vaccine delivery in infants?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Influenza Vaccine - References

References

Kirkpatrick E,Qiu X,Wilson PC,Bahl J,Krammer F, The influenza virus hemagglutinin head evolves faster than the stalk domain. Scientific reports. 2018 Jul 11;     [PubMed]
Grohskopf LA,Sokolow LZ,Broder KR,Walter EB,Fry AM,Jernigan DB, Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices-United States, 2018-19 Influenza Season. MMWR. Recommendations and reports : Morbidity and mortality weekly report. Recommendations and reports. 2018 Aug 24;     [PubMed]
Giles ML,Krishnaswamy S,Wallace EM, Maternal immunisation: What have been the gains? Where are the gaps? What does the future hold? F1000Research. 2018;     [PubMed]
Cohen C,Tshangela A,Valley-Omar Z,Iyengar P,von Mollendorf C,Walaza S,Hellferscee O,Venter M,Martinson N,Mahlase G,McMorrow M,Cowling BJ,Treurnicht FK,Cohen AL,Tempia S, Household transmission of seasonal influenza from HIV-infected and -uninfected individuals in South Africa, 2013-2014. The Journal of infectious diseases. 2018 Dec 12;     [PubMed]
Franco-Paredes C,Carrasco P,Preciado JI, The first influenza pandemic in the new millennium: lessons learned hitherto for current control efforts and overall pandemic preparedness. Journal of immune based therapies and vaccines. 2009 Aug 7;     [PubMed]
Rudenko L,Kiseleva I,Krutikova E,Stepanova E,Rekstin A,Donina S,Pisareva M,Grigorieva E,Kryshen K,Muzhikyan A,Makarova M,Sparrow EG,Torelli G,Kieny MP, Rationale for vaccination with trivalent or quadrivalent live attenuated influenza vaccines: Protective vaccine efficacy in the ferret model. PloS one. 2018;     [PubMed]
Lim JW,Na W,Kim HO,Yeom M,Park G,Kang A,Chun H,Park C,Oh S,Le VP,Jeong HH,Song D,Haam S, Cationic Poly(Amino Acid) Vaccine Adjuvant for Promoting Both Cell-Mediated and Humoral Immunity Against Influenza Virus. Advanced healthcare materials. 2018 Dec 14;     [PubMed]
Sano K,Ainai A,Suzuki T,Hasegawa H, Intranasal inactivated influenza vaccines for the prevention of seasonal influenza epidemics. Expert review of vaccines. 2018 Aug;     [PubMed]
McAllister L,Anderson J,Werth K,Cho I,Copeland K,Le Cam Bouveret N,Plant D,Mendelman PM,Cobb DK, Needle-free jet injection for administration of influenza vaccine: a randomised non-inferiority trial. Lancet (London, England). 2014 Aug 23;     [PubMed]
Choi IJ,Kang A,Ahn MH,Jun H,Baek SK,Park JH,Na W,Choi SO, Insertion-responsive microneedles for rapid intradermal delivery of canine influenza vaccine. Journal of controlled release : official journal of the Controlled Release Society. 2018 Sep 28;     [PubMed]
Belshe RB,Edwards KM,Vesikari T,Black SV,Walker RE,Hultquist M,Kemble G,Connor EM, Live attenuated versus inactivated influenza vaccine in infants and young children. The New England journal of medicine. 2007 Feb 15;     [PubMed]
Klimek L,Wicht-Langhammer S,von Bernus L,Thorn C,Cazan D,Pfaar O,Hörmann K, [Anaphylactic reactions to vaccines : Chicken egg allergy and the influenza H1N1 vaccination]. HNO. 2017 Oct;     [PubMed]
Baggs J,Gee J,Lewis E,Fowler G,Benson P,Lieu T,Naleway A,Klein NP,Baxter R,Belongia E,Glanz J,Hambidge SJ,Jacobsen SJ,Jackson L,Nordin J,Weintraub E, The Vaccine Safety Datalink: a model for monitoring immunization safety. Pediatrics. 2011 May;     [PubMed]
Sasaki E,Momose H,Hiradate Y,Mizukami T,Hamaguchi I, Establishment of a novel safety assessment method for vaccine adjuvant development. Vaccine. 2018 Nov 12;     [PubMed]
Del Giudice G,Rappuoli R,Didierlaurent AM, Correlates of adjuvanticity: A review on adjuvants in licensed vaccines. Seminars in immunology. 2018 Oct;     [PubMed]
Stead M,Critchlow N,Patel R,MacKintosh AM,Sullivan F, Improving uptake of seasonal influenza vaccination by healthcare workers: Implementation differences between higher and lower uptake NHS trusts in England. Infection, disease     [PubMed]
Elbahesh H,Saletti G,Gerlach T,Rimmelzwaan GF, Broadly protective influenza vaccines: design and production platforms. Current opinion in virology. 2018 Nov 26;     [PubMed]
Bresee JS,McKinlay MA,Abramson J,Klugman KP,Wairagkar N, Global Funders Consortium for Universal Influenza Vaccine Development. Vaccine. 2018 Nov 29;     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Ob Gyn-Medical Student. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Ob Gyn-Medical Student, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Ob Gyn-Medical Student, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Ob Gyn-Medical Student. When it is time for the Ob Gyn-Medical Student board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Ob Gyn-Medical Student.