Vaccine-Preventable Diseases & Immunology Flashcards

Subacute sclerosing panencephalitis (SSPE) is a fatal late complication of infection with which pathogen?

Answer: Measles virus

SSPE is a rare, progressive, fatal neurological disorder caused by persistent measles virus infection in the central nervous system, typically manifesting 7–10 years after the initial measles infection.

A patient with a documented severe egg allergy asks about receiving the influenza vaccine. According to current ACIP guidance, which is the most appropriate action?

Answer: Administer any licensed influenza vaccine appropriate for age with observation for 15 minutes afterward

Current ACIP guidance states that egg allergy of any severity is not a contraindication to influenza vaccination; all recommended influenza vaccines may be given with a standard 15-minute observation period.

The rotavirus vaccines are contraindicated in infants with a history of which condition?

Answer: Intussusception or a known predisposing intestinal malformation

History of intussusception or conditions predisposing to intussusception (e.g., Meckel's diverticulum) are contraindications to rotavirus vaccines due to the small increased risk of intussusception associated with the vaccines.

Which mechanism makes conjugate vaccines more immunogenic than plain polysaccharide vaccines in children under 2 years?

Answer: Linking polysaccharide to a protein carrier converts it from a T-independent to a T-dependent antigen, enabling immunological memory

Conjugating polysaccharide antigens to protein carriers recruits T-helper cells, enabling B-cell class switching, affinity maturation, and long-lived immunological memory that plain polysaccharides cannot induce in infants.

Diphtheria toxin causes disease primarily by:

Answer: Inhibiting protein synthesis in host cells by ADP-ribosylation of elongation factor EF-2

Diphtheria toxin ADP-ribosylates elongation factor EF-2 (EF-Tu equivalent), halting protein synthesis and causing cell death, particularly affecting cardiac and neural tissues.

An immunocompromised adult patient on high-dose corticosteroids needs protection against pneumococcal disease. Which vaccine formulation should be preferentially considered?

Answer: PCV20 or PCV15 followed by PPSV23, as conjugate vaccines produce T-cell-dependent responses better suited for immunocompromised patients

Conjugate pneumococcal vaccines (PCV15, PCV20) generate T-cell-dependent immune responses that are more robust in immunocompromised individuals than the T-independent response from PPSV23 alone.

The concept of 'waning immunity' after pertussis vaccination is clinically significant because it explains why:

Answer: Adolescents and adults, despite childhood vaccination, can contract pertussis and transmit it to vulnerable infants

Immunity from acellular pertussis vaccines wanes within 3–5 years, allowing vaccinated adolescents and adults to become susceptible and act as reservoirs transmitting pertussis to unvaccinated or incompletely vaccinated infants.