A mother brings her 4-year-old boy to the physician, as the boy has a 7-day history of foul-smelling diarrhea, abdominal cramps, and fever. The mother adds that he has been vomiting as well, and she is very much worried. The child is in daycare, and the mother endorses sick contacts with both family and friends. The boy has not been vaccinated as the parents do not think it is necessary. On physical exam, the child appears dehydrated. Stool examination is negative for blood cells, pus, and ova or parasites. What is the most likely diagnosis?
Q12
A 12-year-old girl presents to her primary care physician for a well-child visit. She has a history of asthma and uses her inhaler 1-2 times per week when she exercises. She does not smoke and is not currently sexually active; however, she does have a boyfriend. She lives with her mother in an apartment and is doing well in school. Her temperature is 97.6°F (36.4°C), blood pressure is 124/75 mmHg, pulse is 80/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam is notable for a healthy young girl with no findings. Which of the following is most appropriate for this patient at this time?
Q13
An 8-year-old boy is brought to the physician because of worsening confusion and lethargy for the last hour. He has had high-grade fever, productive cough, fatigue, and malaise for 2 days. He was diagnosed with sickle cell anemia at the age of 2 years but has not seen a physician in over a year. His temperature is 38.9°C (102°F), pulse is 133/min, respirations are 33/min, and blood pressure is 86/48 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 92%. The patient does not respond to verbal commands. Examination shows conjunctival pallor and scleral icterus. Inspiratory crackles are heard at the left lung base. Laboratory studies show:
Hemoglobin 8.1 g/dL
Leukocyte count 17,000/mm3
Platelet count 200,000/mm3
Which of the following is most likely to have prevented this patient's condition?
Q14
A 4-year-old boy is brought to the emergency department with difficulty breathing. His mother reports that he developed a fever last night and began to have trouble breathing this morning. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is unvaccinated (conscientious objection by the family) and is meeting all developmental milestones. At the hospital, his vitals are temperature 39.8°C (103.6°F), pulse 122/min, respiration rate 33/min, blood pressure 110/66 mm Hg, and SpO2 93% on room air. On physical examination, he appears ill with his neck hyperextended and chin protruding. His voice is muffled and is drooling. The pediatrician explains that there is one particular bacteria that commonly causes these symptoms. At what age should the patient have first received vaccination to prevent this condition from this particular bacteria?
Q15
A 15-month-old girl is brought to her primary care physician for a follow-up visit to receive the 4th dose of her DTaP vaccine. She is up-to-date on her vaccinations. She received her 1st dose of MMR, 1st dose of varicella, 3rd dose of HiB, 4th dose of PCV13, and 3rd dose of polio vaccine 3 months ago. Thirteen days after receiving these vaccinations, the child developed a fever up to 40.5°C (104.9°F) and had one generalized seizure that lasted for 2 minutes. She was taken to the emergency department. The girl was sent home after workup for the seizure was unremarkable and her temperature subsided with acetaminophen therapy. She has not had any other symptoms since then. She has no history of serious illness and takes no medications. Her mother is concerned about receiving further vaccinations because she is afraid of the girl having more seizures. Her vital signs are within normal limits. Examination shows no abnormalities. Which of the following is the most appropriate recommendation at this time?
Q16
A 28-year-old woman comes to the emergency department for a 1-week history of jaundice and nausea. She recalls eating some seafood last weekend at a cookout. She lives at home with her 2-year-old son who attends a daycare center. The child's immunizations are up-to-date, and his last hepatitis A vaccine was administered 6 weeks ago. The woman's temperature is 37.5°C (99.5°F), pulse is 82/min, and blood pressure is 134/84 mm Hg. Examination shows scleral icterus. The liver is palpated 2-cm below the right costal margin and is tender. Her serum studies show:
Total bilirubin 3.4 mg/dL
Alkaline phosphatase 89 U/L
AST 185 U/L
ALT 723 U/L
Hepatitis A IgM antibody positive
Hepatitis B surface antibody positive
Hepatitis B surface antigen negative
Hepatitis B core IgM antibody negative
Hepatitis C antibody negative
Which of the following health maintenance recommendations is most appropriate for the child at this time?
Q17
An 1800-g (4.0-lb) male newborn is delivered to a 26-year-old woman, gravida 2, para 1, at 33 weeks' gestation. The Apgar scores are 7 at 1 minute and 8 at 5 minutes. The pregnancy was complicated by iron deficiency anemia. The mother has no other history of serious illness. She has smoked one-half pack of cigarettes daily for the past 10 years. She does not drink alcohol. She has never used illicit drugs. Pregnancy and delivery of her first child were complicated by placenta previa. The mother has received all appropriate immunizations. It is most appropriate for the physician to recommend which of the following to the mother regarding her son's immunizations?
Q18
A 2-month-old girl is brought to the physician by her father for a routine well-child examination. She is given a vaccine that contains polyribosylribitol phosphate conjugated to a toxoid carrier. The vaccine is most likely to provide immunity against which of the following pathogens?
Q19
A 12-month-old boy presents for a routine checkup. The patient immigrated from the Philippines with his parents a few months ago. No prior immunization records are available. The patient’s mother claims that he had a series of shots at 6 months of age which gave him a severe allergic reaction with swelling of the tongue and the face. She also remembers that he had the same reaction when she introduced solid foods to his diet, including carrots, eggs, and bananas. Which of the following vaccinations are not recommended for this patient?
Q20
A 4-month-old boy is brought to the physician by his parents for a well-child examination. He has cystic fibrosis diagnosed by newborn screening. His parents report frequent feedings and large-volume and greasy stools. His 4-year-old brother has autism. Current medications include bronchodilators, pancreatic enzyme supplements, and fat-soluble vitamins. He is at the 18th percentile for height and 15th percentile for weight. Scattered wheezes are heard throughout both lung fields. Examination shows a distended and tympanic abdomen with no tenderness or guarding. Which of the following is a contraindication for administering one or more routine vaccinations?
Vaccines US Medical PG Practice Questions and MCQs
Question 11: A mother brings her 4-year-old boy to the physician, as the boy has a 7-day history of foul-smelling diarrhea, abdominal cramps, and fever. The mother adds that he has been vomiting as well, and she is very much worried. The child is in daycare, and the mother endorses sick contacts with both family and friends. The boy has not been vaccinated as the parents do not think it is necessary. On physical exam, the child appears dehydrated. Stool examination is negative for blood cells, pus, and ova or parasites. What is the most likely diagnosis?
A. Rotavirus infection (Correct Answer)
B. Cryptosporidiosis
C. Irritable bowel syndrome
D. C. difficile colitis
E. Norovirus infection
Explanation: ***Rotavirus infection***
- The classic presentation of **foul-smelling diarrhea**, vomiting, abdominal cramps, and fever in an **unvaccinated child** attending daycare strongly suggests rotavirus. This virus is a common cause of **severe gastroenteritis** in young children.
- The absence of bacterial or parasitic indicators in the stool (blood cells, pus, ova/parasites) further narrows the diagnosis to a **viral cause**, with rotavirus being highly prevalent in this age group, especially without vaccination.
*Cryptosporidiosis*
- While it causes **watery diarrhea** and abdominal cramps, it is typically associated with **contaminated water sources** and often produces **oocysts** detectable in stool, which were not found in this case.
- The symptoms in the child are more classic for a common viral gastroenteritis rather than a parasitic infection, especially given the **absence of parasitic elements** on examination.
*Irritable bowel syndrome*
- **IBS** is a chronic functional gastrointestinal disorder and rarely presents acutely with fever and vomiting in a 4-year-old.
- Its diagnosis involves specific **Rome IV criteria** related to chronic abdominal pain and changes in bowel habits, which are not met by the acute presentation here.
*C. difficile colitis*
- **C. difficile colitis** typically follows **antibiotic use** or is acquired in healthcare settings and commonly causes **bloody diarrhea** and significant abdominal pain.
- The diarrhea is usually more profuse and the stool may contain **leukocytes** or be positive for C. difficile toxin, neither of which is indicated in the patient's presentation.
*Norovirus infection*
- Norovirus causes acute gastroenteritis with **vomiting** and **diarrhea**, but the diarrhea is often less foul-smelling and of shorter duration than described.
- While possible, the classic triad of **foul-smelling diarrhea, vomiting, and fever** in an unvaccinated child with sick contacts more strongly points to rotavirus, which tends to cause more severe and prolonged symptoms in young, unvaccinated children.
Question 12: A 12-year-old girl presents to her primary care physician for a well-child visit. She has a history of asthma and uses her inhaler 1-2 times per week when she exercises. She does not smoke and is not currently sexually active; however, she does have a boyfriend. She lives with her mother in an apartment and is doing well in school. Her temperature is 97.6°F (36.4°C), blood pressure is 124/75 mmHg, pulse is 80/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam is notable for a healthy young girl with no findings. Which of the following is most appropriate for this patient at this time?
A. Pelvic examination
B. Serum lipids and cholesterol
C. HPV vaccine (Correct Answer)
D. Hypertension screening
E. Human papilloma virus PCR
Explanation: ***HPV vaccine***
- The **HPV vaccine** is recommended for all adolescents, typically starting at **age 11 or 12**, to prevent HPV-related cancers and genital warts.
- While she may not be currently sexually active, the vaccine is most effective when administered **before exposure** to the virus.
*Pelvic examination*
- A **pelvic examination** is not routinely recommended for a 12-year-old girl during a well-child visit unless there are specific symptoms or concerns.
- The patient has no complaints indicating the need for such an invasive procedure.
*Serum lipids and cholesterol*
- **Lipid screening** is typically recommended for adolescents with risk factors like a family history of early cardiovascular disease or dyslipidemia, or for all adolescents sometime between ages 9 and 11 and again between 17 and 21.
- This patient does not present with any specific risk factors that would warrant immediate screening at this age, and it is not the most appropriate *initial* intervention.
*Hypertension screening*
- **Blood pressure** is already routinely measured at well-child visits, as indicated by the patient's vitals (124/75 mmHg). This is part of the standard physical exam, not a separate intervention to be chosen.
- While her blood pressure is at the higher end for her age, further evaluation would come after initial screening, which has already occurred.
*Human papilloma virus PCR*
- **HPV PCR testing** is used for screening for cervical cancer in adults (typically women age 25 and older) or for diagnostic evaluation of HPV-related lesions.
- This test is not indicated for routine screening in a 12-year-old girl, as it does not prevent HPV and is not a part of adolescent preventive care.
Question 13: An 8-year-old boy is brought to the physician because of worsening confusion and lethargy for the last hour. He has had high-grade fever, productive cough, fatigue, and malaise for 2 days. He was diagnosed with sickle cell anemia at the age of 2 years but has not seen a physician in over a year. His temperature is 38.9°C (102°F), pulse is 133/min, respirations are 33/min, and blood pressure is 86/48 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 92%. The patient does not respond to verbal commands. Examination shows conjunctival pallor and scleral icterus. Inspiratory crackles are heard at the left lung base. Laboratory studies show:
Hemoglobin 8.1 g/dL
Leukocyte count 17,000/mm3
Platelet count 200,000/mm3
Which of the following is most likely to have prevented this patient's condition?
A. Chronic transfusion therapy
B. Pneumococcal vaccination (Correct Answer)
C. Folic acid
D. Low molecular weight heparin
E. Hydroxyurea
Explanation: ***Pneumococcal vaccination***
- This patient with **sickle cell anemia** is presenting with symptoms suggestive of severe **bacterial sepsis and pneumonia** (fever, altered mental status, hypotension, hypoxemia, leukocytosis, crackles). Patients with sickle cell disease are at high risk for **encapsulated bacterial infections**, particularly with *Streptococcus pneumoniae*, due to **functional asplenia** (autosplenectomy from recurrent infarctions).
- **Pneumococcal vaccines** (both **PCV13 conjugate vaccine** and **PPSV23 polysaccharide vaccine**) are crucial for preventing such severe infections in this population. Children with sickle cell disease should receive PCV13 in infancy followed by PPSV23 at age 2 years, with boosters as recommended.
- The neglect of medical care for over a year, including missed vaccinations, likely contributed to this life-threatening presentation.
*Chronic transfusion therapy*
- While chronic transfusion therapy can reduce **stroke risk** and prevent recurrent **vaso-occlusive crises**, it is not primarily used to prevent infectious complications like the one described.
- Transfusions do not directly improve immune function against encapsulated bacteria.
*Folic acid*
- **Folic acid supplementation** is essential in sickle cell anemia to support increased erythropoiesis due to chronic hemolysis.
- It helps prevent **megaloblastic anemia** but does not prevent bacterial infections.
*Low molecular weight heparin*
- **Low molecular weight heparin** is an anticoagulant used to prevent or treat **venous thromboembolism**.
- It has no role in preventing bacterial infections associated with functional asplenia in sickle cell disease.
*Hydroxyurea*
- **Hydroxyurea** increases **fetal hemoglobin (HbF)**, which reduces sickling, vaso-occlusive crises, and acute chest syndrome.
- While it improves overall health and can indirectly reduce infection risk by decreasing hospitalization and improving splenic function in some patients, it does not directly confer protection against encapsulated bacterial infections like vaccination does.
Question 14: A 4-year-old boy is brought to the emergency department with difficulty breathing. His mother reports that he developed a fever last night and began to have trouble breathing this morning. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is unvaccinated (conscientious objection by the family) and is meeting all developmental milestones. At the hospital, his vitals are temperature 39.8°C (103.6°F), pulse 122/min, respiration rate 33/min, blood pressure 110/66 mm Hg, and SpO2 93% on room air. On physical examination, he appears ill with his neck hyperextended and chin protruding. His voice is muffled and is drooling. The pediatrician explains that there is one particular bacteria that commonly causes these symptoms. At what age should the patient have first received vaccination to prevent this condition from this particular bacteria?
A. At birth
B. At 2-months-old (Correct Answer)
C. Between 9- and 12-months-old
D. At 6-months-old
E. Between 12- and 15-months-old
Explanation: ***At 2-months-old***
- The clinical presentation with **high fever**, **difficulty breathing**, **neck hyperextension**, **muffled voice**, and **drooling** in an unvaccinated child strongly suggests **epiglottitis**, likely caused by *Haemophilus influenzae type b* (Hib).
- The **Hib vaccine** is routinely given starting at **2 months of age** as part of the multi-dose primary series to protect against this life-threatening condition.
*At birth*
- While some vaccines like **Hepatitis B** are given at birth, the Hib vaccine is not typically administered at this age.
- Vaccinating at birth would not align with the standard immunization schedule for *Haemophilus influenzae type b*.
*Between 9- and 12-months-old*
- This age range typically corresponds to the **measles, mumps, and rubella (MMR)** and **varicella** vaccines, or a booster dose of other vaccines, not the initial primary series for Hib.
- Delaying the first Hib vaccination until this age would leave infants vulnerable during a critical period.
*At 6-months-old*
- By 6 months, a child should have already received at least **two doses** of the Hib vaccine if following the recommended schedule.
- Administering the first dose at 6 months would significantly delay protection against invasive Hib disease.
*Between 12- and 15-months-old*
- This age range is typically when the **final booster dose** of the Hib vaccine is given, not the initial vaccination.
- The primary series for Hib should have been completed much earlier to provide timely protection.
Question 15: A 15-month-old girl is brought to her primary care physician for a follow-up visit to receive the 4th dose of her DTaP vaccine. She is up-to-date on her vaccinations. She received her 1st dose of MMR, 1st dose of varicella, 3rd dose of HiB, 4th dose of PCV13, and 3rd dose of polio vaccine 3 months ago. Thirteen days after receiving these vaccinations, the child developed a fever up to 40.5°C (104.9°F) and had one generalized seizure that lasted for 2 minutes. She was taken to the emergency department. The girl was sent home after workup for the seizure was unremarkable and her temperature subsided with acetaminophen therapy. She has not had any other symptoms since then. She has no history of serious illness and takes no medications. Her mother is concerned about receiving further vaccinations because she is afraid of the girl having more seizures. Her vital signs are within normal limits. Examination shows no abnormalities. Which of the following is the most appropriate recommendation at this time?
A. Administration of the DTaP vaccine as scheduled (Correct Answer)
B. Administration of the DTaP vaccine with valproic acid
C. Administration of a reduced-dose DTaP vaccine
D. Refrain from administration of the DTaP vaccine
E. Administration of the DTaP vaccine with prophylactic aspirin
Explanation: ***Administration of the DTaP vaccine as scheduled***
- The seizure experienced by the child was a **febrile seizure**, triggered by a fever following vaccination, and not a contraindication to future DTaP doses.
- The timing of the seizure (**13 days post-vaccination**) suggests it was most likely related to the **MMR vaccine**, which commonly causes delayed fever (5-12 days) and febrile seizures, rather than the pertussis component or other vaccines given simultaneously.
- Since the child did **not receive DTaP** at the visit when the febrile seizure occurred, there is no evidence that pertussis-containing vaccines trigger seizures in this patient.
- The **unremarkable workup** and the child's return to normal health indicate the seizure was benign and not indicative of an underlying seizure disorder or severe adverse reaction.
- **Simple febrile seizures are not a contraindication** to DTaP vaccination per CDC/ACIP guidelines.
*Administration of the DTaP vaccine with valproic acid*
- **Valproic acid** is an anti-epileptic drug and is not indicated for the prevention of simple febrile seizures following vaccination.
- Prophylactic use of anti-epileptic drugs for vaccination-related febrile seizures is generally not recommended due to potential side effects and lack of clear benefit.
*Administration of a reduced-dose DTaP vaccine*
- There is **no such thing as a reduced-dose DTaP vaccine** for standard administration in children of this age.
- Reducing the vaccine dose would compromise its efficacy and protective immunity.
*Refrain from administration of the DTaP vaccine*
- **Febrile seizures are not a contraindication** to receiving further DTaP vaccination.
- Withholding the vaccine would leave the child unprotected against **diphtheria, tetanus, and pertussis**, which are serious and potentially life-threatening diseases.
*Administration of the DTaP vaccine with prophylactic aspirin*
- **Aspirin is contraindicated in children** due to the risk of **Reye's syndrome**, especially during viral illnesses or when fever is present.
- It should not be used as a prophylactic measure for vaccination-related fever or seizures.
Question 16: A 28-year-old woman comes to the emergency department for a 1-week history of jaundice and nausea. She recalls eating some seafood last weekend at a cookout. She lives at home with her 2-year-old son who attends a daycare center. The child's immunizations are up-to-date, and his last hepatitis A vaccine was administered 6 weeks ago. The woman's temperature is 37.5°C (99.5°F), pulse is 82/min, and blood pressure is 134/84 mm Hg. Examination shows scleral icterus. The liver is palpated 2-cm below the right costal margin and is tender. Her serum studies show:
Total bilirubin 3.4 mg/dL
Alkaline phosphatase 89 U/L
AST 185 U/L
ALT 723 U/L
Hepatitis A IgM antibody positive
Hepatitis B surface antibody positive
Hepatitis B surface antigen negative
Hepatitis B core IgM antibody negative
Hepatitis C antibody negative
Which of the following health maintenance recommendations is most appropriate for the child at this time?
A. Isolate the child
B. Administer hepatitis B immunoglobulin and hepatitis B vaccine
C. No additional steps are needed (Correct Answer)
D. Administer hepatitis B immunoglobulin only
E. Administer hepatitis A vaccine and hepatitis A immunoglobulin
Explanation: ***No additional steps are needed***
- The child received his **last hepatitis A vaccine 6 weeks ago**, which provides adequate protection against hepatitis A infection.
- According to **CDC/ACIP guidelines**, children who have received **at least one dose** of hepatitis A vaccine do **not require post-exposure prophylaxis** (neither additional vaccine nor immunoglobulin) after exposure to hepatitis A.
- One dose of hepatitis A vaccine provides protection within **2-4 weeks**, and since 6 weeks have elapsed, the child is already immune.
- The child's **immunizations are up-to-date**, confirming he is on the appropriate hepatitis A vaccination schedule (2-dose series).
*Administer hepatitis A vaccine and hepatitis A immunoglobulin*
- This would be appropriate for **previously unvaccinated** individuals exposed to hepatitis A, immunocompromised patients, or infants under 12 months.
- However, this child has **already been vaccinated** 6 weeks ago and therefore has adequate protection.
- Administering both vaccine and immunoglobulin is **unnecessary** and not indicated per current guidelines when prior vaccination has occurred.
*Isolate the child*
- Isolation is not the primary recommendation for hepatitis A post-exposure management in household contacts.
- The focus should be on **prevention through immunization**, but this child is already protected by prior vaccination.
- Standard hygiene measures (handwashing) are recommended but formal isolation is not necessary.
*Administer hepatitis B immunoglobulin and hepatitis B vaccine*
- The mother's serology shows **HBsAg negative** and **HBsAb positive**, indicating she is **immune to hepatitis B** (likely from prior vaccination) and not currently infected.
- There is **no risk of hepatitis B transmission** from the mother to the child.
- This intervention addresses the wrong infection entirely.
*Administer hepatitis B immunoglobulin only*
- This is inappropriate because the mother does **not have active hepatitis B infection** (HBsAg negative).
- This option does not address the **hepatitis A exposure**, which is the relevant concern in this scenario.
- Hepatitis B immunoglobulin is indicated only for exposure to hepatitis B, not hepatitis A.
Question 17: An 1800-g (4.0-lb) male newborn is delivered to a 26-year-old woman, gravida 2, para 1, at 33 weeks' gestation. The Apgar scores are 7 at 1 minute and 8 at 5 minutes. The pregnancy was complicated by iron deficiency anemia. The mother has no other history of serious illness. She has smoked one-half pack of cigarettes daily for the past 10 years. She does not drink alcohol. She has never used illicit drugs. Pregnancy and delivery of her first child were complicated by placenta previa. The mother has received all appropriate immunizations. It is most appropriate for the physician to recommend which of the following to the mother regarding her son's immunizations?
A. Give first dose of varicella vaccine at 2 months of chronological age
B. Give first dose of influenza vaccine at 2 months of chronological age
C. Give first dose of diphtheria and tetanus toxoids, acellular pertussis (DTaP) vaccine at 2 months of chronological age (Correct Answer)
D. Give first dose of hepatitis B vaccine at 3 months of chronological age
E. Give first dose of Haemophilus influenzae type b vaccine at 3 months of chronological age
Explanation: ***Give first dose of diphtheria and tetanus toxoids, acellular pertussis (DTaP) vaccine at 2 months of chronological age***
- The **DTaP vaccine** is routinely recommended for infants starting at **2 months of chronological age**, regardless of prematurity, as long as they are **clinically stable**.
- This timing is crucial for providing early protection against these serious diseases due to the infant's developing immune system and potential vulnerability.
*Give first dose of varicella vaccine at 2 months of chronological age*
- The **varicella vaccine** is a **live attenuated vaccine** and is typically recommended at **12 to 15 months of age**, not at 2 months.
- Administering it to a young infant, especially a premature one, is not standard practice and could be less effective or pose risks.
*Give first dose of influenza vaccine at 2 months of chronological age*
- The **influenza vaccine** is not recommended for infants younger than **6 months of age**.
- Infants receive passive immunity from the mother or rely on cocooning strategies for protection in their first 6 months.
*Give first dose of Haemophilus influenza type b vaccine at 3 months of chronological age*
- The first dose of the **Hib vaccine** is typically given at **2 months of chronological age**, not 3 months, aligning with other routine infant immunizations.
- Delaying this vaccine could leave the infant vulnerable for an unnecessary period.
*Give first dose of hepatitis B vaccine at 3 months of chronological age*
- For premature infants, the **hepatitis B vaccine** is typically initiated at **birth** (if weighing >2000g) or at **1 month of age** or discharge, provided the mother is HBsAg negative.
- Delaying until 3 months is not consistent with current recommendations, especially with the risk factors present (premature birth).
Question 18: A 2-month-old girl is brought to the physician by her father for a routine well-child examination. She is given a vaccine that contains polyribosylribitol phosphate conjugated to a toxoid carrier. The vaccine is most likely to provide immunity against which of the following pathogens?
A. Haemophilus influenzae (Correct Answer)
B. Neisseria meningitidis
C. Bordetella pertussis
D. Streptococcus pneumoniae
E. Corynebacterium diphtheriae
Explanation: **Haemophilus influenzae**
- The vaccine described, containing **polyribosylribitol phosphate (PRP)** conjugated to a toxoid carrier, is characteristic of the **Haemophilus influenzae type b (Hib) vaccine**.
- PRP is the **polysaccharide capsule** of *H. influenzae* type b, and conjugating it to a protein (toxoid carrier) allows for T-cell dependent immunity, effective in infants.
*Neisseria meningitidis*
- While *N. meningitidis* also has a **polysaccharide capsule** and vaccines are available, their capsular components differ (e.g., serogroups A, C, Y, W-135, or B outer membrane protein).
- The description of **polyribosylribitol phosphate** is specific to *H. influenzae* type b.
*Bordetella pertussis*
- Vaccines against *Bordetella pertussis* are typically **acellular pertussis vaccines (aP)**, which contain purified components like pertussis toxoid, filamentous hemagglutinin, and pertactin, not a PRP conjugate.
- These vaccines target bacterial toxins and adhesins, not a polysaccharide capsule unique to PRP.
*Streptococcus pneumoniae*
- Vaccines for *S. pneumoniae* (pneumococcal vaccines) use **capsular polysaccharides** from various serotypes, often conjugated to a protein carrier (e.g., diphtheria toxoid), but the specific polysaccharide is not PRP.
- The structure and serotypes of pneumococcal capsular polysaccharides are distinct from PRP.
*Corynebacterium diphtheriae*
- The vaccine for *C. diphtheriae* is the **diphtheria toxoid**, which is an inactivated form of the diphtheria toxin, not a polysaccharide conjugate.
- It provides immunity by inducing antibodies against the toxin, preventing its harmful effects.
Question 19: A 12-month-old boy presents for a routine checkup. The patient immigrated from the Philippines with his parents a few months ago. No prior immunization records are available. The patient’s mother claims that he had a series of shots at 6 months of age which gave him a severe allergic reaction with swelling of the tongue and the face. She also remembers that he had the same reaction when she introduced solid foods to his diet, including carrots, eggs, and bananas. Which of the following vaccinations are not recommended for this patient?
A. Measles, mumps, and rubella (MMR) vaccine
B. Hepatitis B vaccine
C. Varicella vaccine
D. Intranasal influenza vaccine
E. Intramuscular influenza vaccine (Correct Answer)
Explanation: ***Important Note on Current Guidelines***
Based on **current CDC/ACIP guidelines (2023-2024)**, egg allergy alone is **no longer a contraindication** to influenza vaccines. However, this question tests knowledge of vaccine safety in the context of **severe anaphylaxis to a prior vaccination**.
***Intramuscular influenza vaccine***
- **Historically**, this was considered the most concerning option for patients with severe egg allergy, as many influenza vaccines were produced using egg-based culture methods
- **Current practice**: Per CDC guidelines, persons with egg allergy of any severity can receive any age-appropriate influenza vaccine, as egg protein content is minimal or absent in modern formulations
- However, if this patient had a **documented anaphylactic reaction to the influenza vaccine itself** (not just eggs), then it would be contraindicated
- Given the timing (6 months) and symptoms described, this represents the **historically correct answer**, though modern practice has evolved
*Measles, mumps, and rubella (MMR) vaccine*
- MMR vaccine is grown in **chick embryo fibroblast cells**, NOT in eggs, and contains **no egg protein**
- **Safe for patients with egg allergy** - no contraindication based on egg allergy
- Should be administered on schedule for catch-up immunization
*Hepatitis B vaccine*
- Produced using **recombinant DNA technology in yeast cells**
- Contains **no egg protein** and no animal-derived proteins
- **No contraindication** for this patient - safe to administer
*Varicella vaccine*
- Grown in **human diploid cell cultures**, NOT in eggs
- Contains **no egg protein**
- **Safe for patients with egg allergy** - no contraindication
- Should be administered as part of catch-up immunization
*Intranasal influenza vaccine (LAIV)*
- Like the intramuscular formulation, **current guidelines allow administration** to patients with egg allergy of any severity
- Contains similar or less egg protein than inactivated vaccines in modern formulations
- **Not contraindicated** based solely on egg allergy per current CDC guidelines
Question 20: A 4-month-old boy is brought to the physician by his parents for a well-child examination. He has cystic fibrosis diagnosed by newborn screening. His parents report frequent feedings and large-volume and greasy stools. His 4-year-old brother has autism. Current medications include bronchodilators, pancreatic enzyme supplements, and fat-soluble vitamins. He is at the 18th percentile for height and 15th percentile for weight. Scattered wheezes are heard throughout both lung fields. Examination shows a distended and tympanic abdomen with no tenderness or guarding. Which of the following is a contraindication for administering one or more routine vaccinations?
A. Allergy to egg protein
B. History of cystic fibrosis
C. History of febrile seizures
D. Fever of 38.2°C (100.7°F) following previous vaccinations
E. History of intussusception (Correct Answer)
Explanation: ***History of intussusception***
- A history of **intussusception** is a **contraindication for rotavirus vaccine** administration, as the vaccine itself has a small risk of intussusception, particularly with the first dose.
- The rotavirus vaccine is part of routine childhood immunizations, so this would be a contraindication for one of the routine vaccines.
*Allergy to egg protein*
- Egg allergy is a contraindication primarily for yellow fever vaccine and some influenza vaccines, which are typically not routine vaccinations for a 4-month-old. Many flu vaccines are egg-free or can be safely administered to those with egg allergy under supervision.
- The MMR vaccine is generally safe for those with egg allergy since the amount of egg protein is negligible.
*History of cystic fibrosis*
- **Cystic fibrosis** itself is **not a contraindication** to routine vaccinations; in fact, patients with chronic conditions like CF are often *more* encouraged to receive vaccinations to prevent severe infections.
- The patient's symptoms (poor growth, greasy stools, wheezing) are manifestations of CF, not reasons to defer vaccination.
*History of febrile seizures*
- A history of **febrile seizures** is generally **not a contraindication** to routine vaccinations.
- Parents should be counseled on fever management after vaccination, but the risk of recurrent febrile seizures is not increased by vaccination to a level that warrants deferral.
*Fever of 38.2°C (100.7°F) following previous vaccinations*
- A **low-grade fever** after vaccination is a common and **expected immune response**, not a contraindication for future doses.
- Only a **severe allergic reaction** (e.g., anaphylaxis) to a previous dose of a vaccine or one of its components is a contraindication to subsequent doses of that specific vaccine.
