Influenza Virus Overview

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Questions and Answers

What type of influenza virus is known for infecting multiple species, including humans, swine, equines, and birds?

  • Influenza A (correct)
  • Influenza B
  • Influenza C
  • Influenza D

Which surface protein is primarily associated with the virion envelope of influenza?

  • Nucleoprotein
  • Fusion protein
  • Glycoprotein
  • Hemagglutinin (HA) (correct)

Which of the following describes the process of antigenic DRIFT?

  • Sudden mutations due to environmental stress
  • Major changes in HA or NA resulting in novel subtypes
  • Gradual amino acid substitutions causing smaller outbreaks (correct)
  • Complete genetic reassortment between viruses

Which vaccine formulation is recommended for a quadrivalent influenza vaccine that is also egg-free?

<p>Recombinant inactivated vaccine (RIV) (A)</p> Signup and view all the answers

Which population is specifically contraindicated for the use of the Live Attenuated Influenza Vaccine (LAIV)?

<p>Pregnant patients (A)</p> Signup and view all the answers

What is the primary cause of antigenic variation in influenza viruses?

<p>Changes in HA or NA surface proteins (A)</p> Signup and view all the answers

What differentiates antigenic SHIFT from antigenic DRIFT in influenza viruses?

<p>SHIFT creates widespread pandemics; DRIFT results in localized outbreaks (D)</p> Signup and view all the answers

What type of influenza virus primarily causes major pandemics due to its susceptibility to antigenic variation?

<p>Influenza A (C)</p> Signup and view all the answers

Which groups are considered at high risk for influenza complications, warranting specific vaccination recommendations?

<p>Patients with severe immune deficiency, including those post-transplant (D)</p> Signup and view all the answers

What is the recommended timing for initiating antiviral treatment for influenza to ensure maximum clinical benefit?

<p>Within 24 hours of symptom onset (B)</p> Signup and view all the answers

Which antiviral drug is NOT classified as a neuraminidase inhibitor (NA inhibitor)?

<p>Baloxavir (C)</p> Signup and view all the answers

What is the minimum age at which annual influenza vaccination is recommended?

<p>6 months (B)</p> Signup and view all the answers

Which of the following scenarios warrants the use of pre-exposure chemoprophylaxis for influenza?

<p>Individuals with severe immune deficiency unable to receive vaccination (B)</p> Signup and view all the answers

Which factors contribute to a child aged 2-4 years being considered for increased influenza risk?

<p>History of asthma or wheezing within the past 12 months (B)</p> Signup and view all the answers

In the clinical prediction rule for diagnosing influenza, how many points are assigned for myalgias?

<p>2 points (C)</p> Signup and view all the answers

Which method is preferred for the prevention of influenza in general?

<p>Vaccination (B)</p> Signup and view all the answers

What is the recommended interval for giving the inactivated influenza vaccine to children aged 6 months to 8 years?

<p>4 weeks apart (A)</p> Signup and view all the answers

Is routine widespread chemoprophylaxis with antivirals recommended outside of institutional outbreaks?

<p>No, it is not recommended (D)</p> Signup and view all the answers

Which symptom combination yields the highest points in the clinical prediction rule for diagnosing influenza?

<p>Fever and cough, myalgias (D)</p> Signup and view all the answers

What is the maximum time frame within which antiviral treatment should ideally be initiated for influenza to ensure clinical benefit?

<p>24 hours after symptom onset (D)</p> Signup and view all the answers

Which antiviral drug is categorized as a Cap dependent endonuclear inhibitor?

<p>Baloxavir (A)</p> Signup and view all the answers

What should be the approach towards chemoprophylaxis with NA inhibitors for patients?

<p>Recommended for specific high-risk populations only (D)</p> Signup and view all the answers

Which of the following populations is NOT indicated for post-exposure chemoprophylaxis?

<p>Individuals recently vaccinated against influenza (D)</p> Signup and view all the answers

Which treatment is preferred for influenza in pregnant women?

<p>Oral Oseltamivir (C)</p> Signup and view all the answers

For children aged 6 months to 8 years, how many doses of inactivated influenza vaccine are recommended?

<p>2 doses at least 4 weeks apart (A)</p> Signup and view all the answers

Which of the following statements about routine widespread chemoprophylaxis for antiviral drugs is accurate?

<p>Not recommended outside of institutional outbreaks (A)</p> Signup and view all the answers

What type of influenza virus is most associated with significant changes that create novel subtypes capable of causing widespread pandemics?

<p>Influenza A (A)</p> Signup and view all the answers

Who among the following is considered eligible for pre-exposure chemoprophylaxis?

<p>Patients who cannot receive vaccinations (B)</p> Signup and view all the answers

Which age group is advised to receive annual influenza vaccination?

<p>Children 6 months and older (A)</p> Signup and view all the answers

What are the two mechanisms of antigenic variation in influenza viruses?

<p>Antigenic drift and antigenic shift (D)</p> Signup and view all the answers

Which protein on the surface of the influenza virion envelope is primarily responsible for facilitating viral entry into host cells?

<p>Hemagglutinin (C)</p> Signup and view all the answers

Which statement accurately describes antigenic drift in influenza viruses?

<p>It causes gradual amino acid substitutions. (A)</p> Signup and view all the answers

In which type of population is the Live Attenuated Influenza Vaccine (LAIV) contraindicated?

<p>Pregnant individuals (D)</p> Signup and view all the answers

Which influenza vaccine formulation is suitable for individuals who require an egg-free option?

<p>Recombinant inactivated vaccine (RIV) (A)</p> Signup and view all the answers

What is the recommended strategy for influenza vaccination for healthy individuals over six months of age?

<p>Annual vaccination for all without contraindications (B)</p> Signup and view all the answers

What characterizes antigenic shift in the context of influenza viruses?

<p>Sudden and significant mutations creating new subtypes (B)</p> Signup and view all the answers

Flashcards

Influenza Viruses

RNA viruses belonging to the Orthomyxoviridae family that infect humans, swine, equines, and birds.

Types of Influenza Viruses

Influenza viruses, classified into three types: A, B, and C, with type A having the widest host range.

Antigenic Variation

Changes in surface proteins (hemagglutinin (HA) and neuraminidase (NA)) of influenza viruses, leading to variations in the virus's ability to evade the immune system.

Antigenic Drift

Small, gradual changes in amino acid sequences of HA and NA proteins, leading to minor outbreaks and increased risk of infection for those with prior immunity.

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Antigenic Shift

Major changes in HA and NA proteins due to genetic reassortment, resulting in novel influenza subtypes that can cause pandemics (large-scale outbreaks).

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Influenza Vaccination

Recommended for everyone 6 months and older to prevent influenza, with options like inactivated influenza vaccines (IIV), recombinant inactivated vaccines (RIV), and live attenuated influenza vaccine (LAIV).

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Inactivated Influenza Vaccine (IIV)

Inactivated influenza vaccines (IIV) contain killed virus particles, providing immunity without risk of infection.

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Recombinant Inactivated Vaccine (RIV)

Recombinant influenza vaccines (RIV) produced using cell cultures instead of eggs, providing an alternative for egg allergies.

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Live Attenuated Influenza Vaccine (LAIV)

Live attenuated influenza vaccine (LAIV) uses weakened virus that replicates in the nasal passages, providing closer to natural immunity.

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Contraindications for LAIV

Contraindicated in pregnant individuals and those with compromised immune systems, as it can replicate and potentially cause harm.

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Quadrivalent Influenza Vaccine

Containing multiple strains of influenza, offering broader protection against different viruses.

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IIV Preference for Vaccination

Generally preferred over LAIV for most individuals, especially those at higher risk of complications.

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Children's Influenza Vaccine Dosing

Two doses of IIV are required for children aged 6 months to 8 years, spaced at least four weeks apart, to achieve optimal immune response.

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Clinical Prediction Rule for Influenza

A symptom-based clinical prediction rule used to aid in diagnosing influenza.

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Antiviral Treatment for Influenza

Antiviral medications effective in reducing the severity and duration of influenza when initiated within 24 hours of symptom onset.

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Oseltamivir (Tamiflu)

A neuraminidase inhibitor used to treat influenza, available orally and as an inhalant.

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Zanamivir (Relenza)

Another neuraminidase inhibitor for treating influenza, administered through inhalation.

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Peramivir

An intravenous antiviral drug, given via injection, used for treating severe influenza cases.

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Baloxavir Marboxil (Xofluza)

A novel antiviral treatment for influenza that inhibits viral replication, effective even when started later in the illness.

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Chemoprophylaxis for Influenza

The use of antiviral medications to prevent influenza infection in high-risk individuals or those exposed to the virus.

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Pre-exposure Prophylaxis

Administering antiviral medications to individuals at higher risk of complications before exposure to influenza, such as those with immune deficiencies.

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Post-exposure Prophylaxis

Administering antiviral medication to individuals within 48 hours of exposure to influenza to reduce the risk of infection or severe illness.

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Vaccination for Influenza Prevention

Vaccination is the most effective means of preventing influenza infection, particularly during outbreaks and for high-risk populations.

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Influenza Treatment During Pregnancy

Oral oseltamivir is the preferred treatment option for pregnant individuals with influenza.

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Antiviral Chemoprophylaxis Limitations

Antivirals should not be used routinely to prevent influenza infection outside of outbreaks and high-risk scenarios.

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Study Notes

Influenza Overview

  • Influenza viruses are RNA viruses belonging to the Orthomyxoviridae family.
  • Three types infect humans: Influenza A, B, and C.
  • Influenza A has the broadest host range, infecting humans, swine, equines, and birds.

Antigenic Variation

  • Antigenic variation in influenza arises from changes in hemagglutinin (HA) and neuraminidase (NA) surface proteins.
  • Two types of antigenic variation:
    • Antigenic Drift: Small, gradual amino acid changes leading to minor outbreaks.
    • Antigenic Shift: Major changes resulting in novel subtypes that can cause pandemics.

Vaccination Recommendations

  • Annual influenza vaccination is advised for everyone aged six months and older without contraindications.
  • Vaccination options include:
    • Inactivated Influenza Vaccines (IIV)
    • Recombinant Inactivated Vaccine (RIV)
    • Live Attenuated Influenza Vaccine (LAIV), contraindicated in pregnant individuals and specific high-risk populations.
  • Quadrivalent vaccines are egg-free.

Vaccine Administration

  • IIV preferred over LAIV for vaccination.
  • Children aged 6 months to 8 years need two doses of IIV, spaced at least four weeks apart.

Clinical Prediction and Treatment

  • A symptom-based clinical prediction rule assists in diagnosing influenza with point assignments for fever, cough, myalgias, and early symptom onset.
  • Antiviral treatments are effective if initiated within 24 hours of symptom onset.
  • Approved antiviral drugs include:
    • Oseltamivir (NA inhibitor)
    • Zanamivir (NA inhibitor)
    • Peramivir (NA inhibitor)
    • Baloxavir (Cap-dependent endonuclease inhibitor)

Chemoprophylaxis Guidelines

  • Chemoprophylaxis with NA inhibitors is not universally recommended, only for specific high-risk populations.
  • Pre-exposure prophylaxis is suitable for individuals with immune deficiencies or those in close contact with at-risk populations.
  • Post-exposure prophylaxis should be initiated within 48 hours of exposure to influenza, especially for unvaccinated high-risk individuals.

Preferred Treatment and Prevention

  • Vaccination remains the primary method for preventing influenza.
  • Oral Oseltamivir is the preferred treatment for influenza during pregnancy.
  • Antivirals should not be used for routine chemoprophylaxis outside of outbreaks.

Influenza Overview

  • Influenza viruses are RNA viruses belonging to the Orthomyxoviridae family.
  • Three types infect humans: Influenza A, B, and C.
  • Influenza A has the broadest host range, infecting humans, swine, equines, and birds.

Antigenic Variation

  • Antigenic variation in influenza arises from changes in hemagglutinin (HA) and neuraminidase (NA) surface proteins.
  • Two types of antigenic variation:
    • Antigenic Drift: Small, gradual amino acid changes leading to minor outbreaks.
    • Antigenic Shift: Major changes resulting in novel subtypes that can cause pandemics.

Vaccination Recommendations

  • Annual influenza vaccination is advised for everyone aged six months and older without contraindications.
  • Vaccination options include:
    • Inactivated Influenza Vaccines (IIV)
    • Recombinant Inactivated Vaccine (RIV)
    • Live Attenuated Influenza Vaccine (LAIV), contraindicated in pregnant individuals and specific high-risk populations.
  • Quadrivalent vaccines are egg-free.

Vaccine Administration

  • IIV preferred over LAIV for vaccination.
  • Children aged 6 months to 8 years need two doses of IIV, spaced at least four weeks apart.

Clinical Prediction and Treatment

  • A symptom-based clinical prediction rule assists in diagnosing influenza with point assignments for fever, cough, myalgias, and early symptom onset.
  • Antiviral treatments are effective if initiated within 24 hours of symptom onset.
  • Approved antiviral drugs include:
    • Oseltamivir (NA inhibitor)
    • Zanamivir (NA inhibitor)
    • Peramivir (NA inhibitor)
    • Baloxavir (Cap-dependent endonuclease inhibitor)

Chemoprophylaxis Guidelines

  • Chemoprophylaxis with NA inhibitors is not universally recommended, only for specific high-risk populations.
  • Pre-exposure prophylaxis is suitable for individuals with immune deficiencies or those in close contact with at-risk populations.
  • Post-exposure prophylaxis should be initiated within 48 hours of exposure to influenza, especially for unvaccinated high-risk individuals.

Preferred Treatment and Prevention

  • Vaccination remains the primary method for preventing influenza.
  • Oral Oseltamivir is the preferred treatment for influenza during pregnancy.
  • Antivirals should not be used for routine chemoprophylaxis outside of outbreaks.

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