{"id":3785,"date":"2023-07-05T20:31:00","date_gmt":"2023-07-05T20:31:00","guid":{"rendered":"https:\/\/www.osmosis.org\/blog\/?p=3785"},"modified":"2025-10-01T11:39:35","modified_gmt":"2025-10-01T19:39:35","slug":"usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid","status":"publish","type":"post","link":"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid","title":{"rendered":"USMLE\u00ae Step 1 Question of the Day: Severe-combined immunodeficiency (SCID)"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_80 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">In This Article<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#The_correct_answer_to_todays_USMLE%C2%AE_Step_1_Question_is%E2%80%A6\" >The correct answer to today&#8217;s USMLE\u00ae Step 1 Question is&#8230;<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#A_Rotavirus_vaccine\" >A. Rotavirus vaccine<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#Incorrect_answer_explanations\" >Incorrect answer explanations<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#B_Hepatitis_B_vaccine\" >B. Hepatitis B vaccine&nbsp;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#C_Diphtheria-tetanus-acellular_pertussis_DTaP_vaccine\" >C. Diphtheria-tetanus-acellular pertussis (DTaP) vaccine&nbsp;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#D_Streptococcus_pneumoniae_vaccine\" >D. Streptococcus pneumoniae vaccine&nbsp;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#E_Intramuscular_influenza_vaccine\" >E. Intramuscular influenza vaccine&nbsp;<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#Main_Explanation\" >Main Explanation<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#Major_Takeaway\" >Major Takeaway<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\/#i\" >&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;________________________<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n\n<p class=\"wp-block-paragraph\"><strong><em>Learn about vaccines and contraindications in a 4-month-old male infant diagnosed with severe-combined immunodeficiency (SCID). Explore which vaccines are contraindicated in this specific case to enhance your pediatric knowledge. Get ready for the USMLE\u00ae with this question of the day.<\/em><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A 4-month-old male infant is brought to the pediatrician by his mother for follow-up. The mother asks the pediatrician about the vaccines that her child must receive. He was diagnosed with severe-combined immunodeficiency (SCID) at two months. Which of the following vaccines are contraindicated in this child?&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>A. Rotavirus vaccine<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>B. Hepatitis B vaccine<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>C. Diphtheria-tetanus-acellular pertussis (DTaP) vaccine<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>D.&nbsp;<em>Streptococcus pneumoniae<\/em>&nbsp;vaccine<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>E. Intramuscular influenza vaccine<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Scroll down for the correct answer!<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"The_correct_answer_to_todays_USMLE%C2%AE_Step_1_Question_is%E2%80%A6\"><\/span>The correct answer to today&#8217;s USMLE\u00ae Step 1 Question is&#8230;<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"A_Rotavirus_vaccine\"><\/span>A. Rotavirus vaccine<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Before we get to the Main Explanation, let&#8217;s look at the incorrect answer explanations. Skip to the bottom if you want to see the correct answer right away!<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Incorrect_answer_explanations\"><\/span>Incorrect answer explanations<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"B_Hepatitis_B_vaccine\"><\/span>B. Hepatitis B vaccine&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>&nbsp;Hepatitis B is a subunit vaccine that can be administered to patients with immunodeficiencies.&nbsp;<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"C_Diphtheria-tetanus-acellular_pertussis_DTaP_vaccine\"><\/span>C. Diphtheria-tetanus-acellular pertussis (DTaP) vaccine&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>&nbsp;DTaP is not contraindicated in patients with immunodeficiencies because it is not a live-attenuated vaccine.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"D_Streptococcus_pneumoniae_vaccine\"><\/span>D. Streptococcus pneumoniae vaccine&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:&nbsp;<\/strong>The Streptococcus pneumoniae vaccine is a subunit vaccine that is not contraindicated in patients with immunodeficiencies.&nbsp;<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"E_Intramuscular_influenza_vaccine\"><\/span>E. Intramuscular influenza vaccine&nbsp;<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>&nbsp;Intramuscular influenza is a killed vaccine that can be safely given to patients with immunodeficiencies.&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Main_Explanation\"><\/span><strong>Main Explanation<\/strong><span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Live attenuated vaccines<\/strong>&nbsp;are a form of&nbsp;<strong>active immunization<\/strong>. Live attenuated vaccines are one type of whole-cell vaccine in which the recipient is injected with a live form of a pathogen. In live-attenuated vaccines, the pathogen is weakened but not killed; therefore, it is less pathogenic but can replicate inside the host\u2019s body. The replicating pathogen then activates the adaptive immune system that involves both the humoral and the cellular immune systems, resulting in a strong immune response&nbsp;<strong>nearly as strong as a typical infection<\/strong>. &nbsp;This is the primary advantage of live-attenuated vaccines because the immunity produced by such vaccines is the strongest and longest-lasting of all types of vaccination and can last up to several decades after a single immunization.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, live-attenuated vaccines have some side effects. Because the living form of the pathogen is injected, it can, in some cases, cause disease, especially in patients with low immunity (e.g., patients with AIDS and patients with severe combined immunodeficiency). Therefore, live-attenuated vaccines are&nbsp;<strong>contraindicated in patients with immunodeficiencies<\/strong>.&nbsp;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Examples of live-attenuated vaccines include the Mumps-Measles-Rubella vaccine, rotavirus vaccine, intranasal influenza vaccine, chickenpox, smallpox vaccine, and yellow fever vaccine.&nbsp;<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Major_Takeaway\"><\/span>Major Takeaway<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Live-attenuated vaccines are contraindicated in patients with immunodeficiencies. Examples of live-attenuated vaccines include the Mumps-Measles-Rubella vaccine, rotavirus vaccine, intranasal influenza vaccine, chickenpox, smallpox vaccine, and yellow fever vaccine.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"i\"><\/span><strong><em>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;________________________<\/em><\/strong><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>Want more USMLE\u00ae Step 1 practice questions? Try Osmosis today! Access your\u00a0<em><strong><a href=\"https:\/\/www.osmosis.org\/login?type=create\" target=\"_blank\" rel=\"noreferrer noopener\">free trial<\/a><\/strong><\/em>\u00a0and find out why millions of current and future clinicians and caregivers love learning with us.<\/strong><\/em><\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/www.osmosis.org\/ultimate-guide\/usmle-step-1\"><img loading=\"lazy\" decoding=\"async\" width=\"700\" height=\"250\" src=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/image_f3842d.png\" alt=\"Osmosis sign up ad\" class=\"wp-image-3787\" srcset=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/image_f3842d.png 700w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/image_f3842d.png?resize=300,107 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.osmosis.org\/ultimate-guide\/usmle-step-1\" target=\"_blank\" rel=\"noreferrer noopener\"><\/a><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><em><sub>The United States Medical Licensing Examination (USMLE\u00ae) is a joint program of the Federation of State Medical Boards (FSMB\u00ae) and National Board of Medical Examiners (NBME\u00ae). Osmosis is not affiliated with NBME nor FSMB.&nbsp;<\/sub><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Learn about vaccines and contraindications in a 4-month-old male infant diagnosed with severe-combined immunodeficiency (SCID). Explore which vaccines are contraindicated in this specific case to enhance your pediatric knowledge. Get ready for the USMLE\u00ae with this question of the day. A 4-month-old male infant is brought to the pediatrician by his mother for follow-up. The [&hellip;]<\/p>\n","protected":false},"author":202,"featured_media":3786,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[27,20,1369,44],"tags":[],"class_list":["post-3785","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicine","category-exam-prep","category-step-1-questions","category-step-1"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.6 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>USMLE\u00ae Step 1 Question of the Day: Severe-combined immunodeficiency (SCID) - Osmosis Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-severe-combined-immunodeficiency-scid\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"USMLE\u00ae Step 1 Question of the Day: Severe-combined immunodeficiency (SCID) - Osmosis Blog\" \/>\n<meta property=\"og:description\" content=\"Learn about vaccines and contraindications in a 4-month-old male infant diagnosed with severe-combined immunodeficiency (SCID). 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Understand why full informed consent is essential before sterilization.","rel":"","context":"In &quot;Allopathic Medicine (MD)&quot;","block_context":{"text":"Allopathic Medicine (MD)","link":"https:\/\/www.osmosis.org\/blog\/category\/medicine"},"img":{"alt_text":"USMLE Step 2 Question of the Day: LARC","src":"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/12\/Step_2_CK_QOTD_Q4_2024_JTD_1.jpg","width":350,"height":200,"srcset":"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/12\/Step_2_CK_QOTD_Q4_2024_JTD_1.jpg 1x, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/12\/Step_2_CK_QOTD_Q4_2024_JTD_1.jpg 1.5x, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/12\/Step_2_CK_QOTD_Q4_2024_JTD_1.jpg 2x"},"classes":[]}],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/posts\/3785","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/users\/202"}],"replies":[{"embeddable":true,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/comments?post=3785"}],"version-history":[{"count":1,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/posts\/3785\/revisions"}],"predecessor-version":[{"id":3788,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/posts\/3785\/revisions\/3788"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/media\/3786"}],"wp:attachment":[{"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/media?parent=3785"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/categories?post=3785"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.osmosis.org\/blog\/wp-json\/wp\/v2\/tags?post=3785"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}