[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"$fxLN3MUwXCdr5RPjwZYIDpOj8CHyjOmngWTgoKXPtZbg":3,"$f4I3Fj8MytFSxSKpedqxKutGgWFNyy_lfw2uFruI171A":32,"$f3Ft0rKFJHppdzE-vuveecxx1BUcg9iOlMLtyzf_MJDg":75},[4,8,12,16,20,24,28],{"title":5,"slug":6,"path":7},"About Microbeonline.com","about-microbeonline-com","\u002Fabout-microbeonline-com\u002F",{"title":9,"slug":10,"path":11},"About Me","about-me","\u002Fabout-microbeonline-com\u002Fabout-me\u002F",{"title":13,"slug":14,"path":15},"Advertise with Us","advertise-us","\u002Fadvertise-us\u002F",{"title":17,"slug":18,"path":19},"Privacy Policy","privacy-policy","\u002Fprivacy-policy\u002F",{"title":21,"slug":22,"path":23},"Abbreviations","abbreviations","\u002Fabbreviations\u002F",{"title":25,"slug":26,"path":27},"Microbes","microbes","\u002Fmicrobes\u002F",{"title":29,"slug":30,"path":31},"Books","recommended-books","\u002Frecommended-books\u002F",{"type":33,"data":34},"blog",{"slug":35,"title":36,"description":36,"author":37,"date":38,"updatedDate":39,"draft":40,"category":41,"tags":42,"image":43,"body":44,"_id":45,"related":46},"killed-or-live-vaccine-which-one-to-choose","Killed or Live Vaccine, Which One to Choose?","Acharya Tankeshwar","2022-04-25","2025-12-29",false,"general-microbiology",[],"","Live, attenuated vaccines and inactivated vaccines are two basic types of vaccines used to protect susceptible individuals from infectious diseases.\n\n## Live-attenuated vaccines\n\n**Live-attenuated vaccines** contain live pathogens, either bacteria or viruses that have been “attenuated,” or weakened. Wild viruses or bacteria are attenuated in a laboratory, usually by repeated culturing. For example, a live attenuated measles vaccine was prepared by almost 10 years of serial passage using tissue culture media.\n\nLive-attenuated vaccines are strong enough to trigger the immune response and produce neutralizing antibodies but too weak to cause disease. If caused disease, it is usually much milder and is considered an adverse reaction to the vaccine.\n\n![ - Live attenuated vaccine production and working mechanism (image source: pfizer)](\u002Fblogs\u002FLive-attenuated-vaccine.jpg)Figure: Live attenuated vaccine production and working mechanism (image source: pfizer)\n\n### Benefits of Live Vaccines\n\nThe immune response to a live, attenuated vaccine is virtually identical to that produced by a natural infection. In general, live vaccines are preferred to killed vaccines because they offer greater and long-lasting protection.\n\n- When a live vaccine is administered through the natural route of infection, for example, when the polio vaccine is given orally, it multiplies in the intestinal cells of the host and elicits the production of [IgA](\u002Fimmunoglobulin-iga-structure-functions\u002F) and [IgG](\u002Figg-antibody-structure-subclasses-functions-and-clinical-significance\u002F) antibodies.\n- Additional doses, or booster shots, are not always needed with live-attenuated vaccines because the immune system recognizes and remembers live pathogens for a very long period of time.\n\n> Although live vaccines stimulate a long-lasting response, booster doses are now recommended with measles and polio vaccines.\n\n### Examplesof Live Vaccines\n\n- **Bacillus Calmette-Guerin (BCG) vaccine** contains live attenuated strains of *Mycobacterium bovis.* It is given to prevent tuberculosis and other mycobacterial infections. BCG vaccine is also used to treat bladder cancer. The vaccine is instilled into the bladder and serves to nonspecifically stimulate [cell-mediated immunity](\u002Fcell-mediated-immunity\u002F), which can inhibit the growth of cancer cells.\n- An oral, live attenuated **cholera vaccine (Vaxchora)** is used to immunize susceptible travelers (age 2 to 64 years) against disease caused by *Vibrio cholerae*serogroup O1 if they are traveling to cholera-affected areas.\n- **Influenza vaccine**contains temperature-sensitive mutants of influenza virus as the immunogen. This mutant replicates only in the cooler air passage of the ost and induces IgA-based immunity. As it can not replicate in the warmer lung tissue, it fails to cause disease.\n- Measles, mumps, and rubella **(MMR) vaccine** is a live, attenuated vaccine that is effective and long-lasting (at least 10 years) to prevent infection with measles, mumps, and rubella (German measles) virus. Two immunizations are recommended, one at 9-15 months and the booster dose at 4-6 years.\n- Live, attenuated **polio vaccine**, also known as Sabin vaccine or oral polio vaccine (OPV) is used to prevent poliomyelitis. Though both killed\u002Finactivated vaccine and live vaccine are available at present, the inactivated vaccine is preferred because of outbreaks of paralytic polio caused by vaccine-derived poliovirus (VDPV).\n- **Live, attenuated vaccine against rotavirus** (Rotarix) contains the single most common rotavirus serotype (G1) and is given to children (exception children with a history of intussusception) to protect from rotavirus infection.\n- \\*\\*Varicella vaccine (Varivax) and zoster vaccine (Zostavax)\\*\\*contain live, attenuated [varicella zoster virus](\u002Fvaricella-zoster-virus-chicken-pox-and-shingles\u002F). They are used to prevent varicella and zoster respectively. Zostavax contains 14 times more virus than Varivax. The varicella vaccine is recommended for children of 1-12 years, whereas the zoster vaccines are recommended for people older than 50 years.\n\n### Limitations of Live Vaccines\n\n1. Attenuated strains of pathogens **may revert to virulent form** either during the production of vaccines or in the immunized person. Of the commonly used live vaccines, only a polio vaccine has had problems regarding reversion to wild forms. Such reversions have not yet been seen with measles, mumps, rubella, and varicella vaccines.\n2. Live vaccine **should not be given to immunocompromised people or to pregnant women** because although attenuated (weakened), it can still be pathogenic in hosts with weakened immunity. Live, attenuated vaccine may cause severe or fatal infections in persons with a weakened immune system (people suffering from leukemia, HIV infection, or ongoing treatment with certain drugs).\n3. Vaccinated individuals excrete live vaccines in the environment. It is a **double-edged sword.** For example, the spread of the live attenuated poliovirus vaccine through the feces of the immunized individuals can successfully immunize other persons in that particular locality thus aiding in the production of herd immunity but if the virus reverts to wild type, the neurovirulent strain may spread to susceptible person and may cause paralytic polio (a rare event though).\n4. **Contamination of the candidate vaccine** by another virus during production may create problems.\n5. Live, attenuated vaccines must be stored and handled carefully as they are fragile and **can be damaged or destroyed by heat and light.**\n6. Circulating antibodies if present in the host (antibodies transferred from mother to child or antibodies due to previous sub-clinical infections or got via transfusion of blood products) can interfere with the replication of the vaccine organism and lead to poor response or no response to the vaccine, also known as **vaccine failure.**\n\n> Note: People who are allergic to eggs (who have shown anaphylactic reactions to eggs) should not get vaccines grown in chick embryos. For example, influenza, measles, mumps, and yellow fever vaccines.\n\n## Inactivated (killed) vaccines\n\n**Inactivated or killed vaccines** contain “wild viruses or bacteria that have been killed or inactivated with heat or chemicals. Viral vaccines are inactivated with either formaldehyde or beta-propiolactone (BPL). Formaldehyde is used for the inactivation of [poliovirus](\u002Fsalk-and-sabin-vaccine\u002F), hepatitis A virus, [Japanese encephalitis virus](\u002Fjapanese-encephalitis-je-virus-structure-life-cycle-pathogenesis-diagnosis\u002F), and tick-borne encephalitis virus whereas BPL is used for the inactivation of Rabies and Influenza virus vaccines.\n\nInactivated vaccines include whole-cell inactivated vaccines (such as polio, hepatitis A, and rabies vaccine), subunit vaccines (e.g., influenza pneumococcal vaccines), toxoids (e.g., diphtheria and tetanus toxoid), and recombinant vaccines (e.g., hepatitis B, human papillomavirus (HPV) and influenza). Killed vaccines are usually given intramuscularly and multiple doses are required to produce protective immunity. Inactivated vaccines mostly provide humoral immunity with little or no cell-mediated immunity.\n\n![ - Live attenuated vaccine production and working mechanism (image source: Pfizer)](\u002Fblogs\u002FInactivated-Vaccine.jpg)Figure: Live attenuated vaccine production and working mechanism (image source: Pfizer)\n\n### Benefits of Killed Vaccine\n\n- Inactivated vaccines are safe for immunocompromised people as they cannot revert to virulence. Killed vaccine can be used to immunize pregnant women.\n\n- Killed vaccines are more heat-stable so are easy to handle (storage and transport won’t be the problem, compared with live vaccines).\n\n### Limitations of Killed Vaccine\n\n- Inactivated vaccines are weaker than natural infection or live vaccines, so they **often require multiple shots i**n order to build immunity and offer full protection. For example, killed vaccines against the influenza virus must be given annually as it is not a good immunogen.\n- The killed vaccine is not a good immunogen, it only **stimulates the production of only IgG (not IgA and IgG both), that too with low titer.** Killed vaccines also do not stimulate a cytotoxic-T-cell response.\n- Antibody titers against inactivated vaccines diminish with time. As a result, some inactivated vaccines may require periodic supplemental doses to increase or “boost” antibody titers.\n\n### Examples of Killed Vaccines\n\n1. Killed **Vibrio cholerae vaccine** is used in many cholera endemic countries.\n2. Killed **polio vaccine** also known as IPV or Salk vaccine is the preferred vaccine to prevent poliomyelitis. It contains all three serotypes of the virus responsible for causing poliomyelitis. The current version of the inactivated vaccine is called enhanced polio vaccine, or eIPV. eIPV has a higher seroconversion rate and induces a higher titer of antibody compared to previous IPV.\n3. Killed **Yersinia pestis vaccine** is indicated for persons at high risk for contracting plague.\n4. **Vaccine against typhus** contains killed *Rickettsia rickettsiae* and is used primarily to immunize members of the armed forces.\n5. The **vaccine against Q fever** contains killed *Coxiella burnetii*. It is used to immunize those who are at high risk of being exposed to animals infected with the organism.\n\n## Difference Between Live and Killed Vaccines\n\n| Characteristic | Live Vaccine | Killed Vaccine |\n| --- | --- | --- |\n| Duration of immunity | Longer | Shorter |\n| Effectiveness of protection | Greater | Lower |\n| Immunoglobulins produced | IgA (if the vaccine is given via the natural route) and IgG | IgG |\n| Production of Cell-mediated immunity | Yes | Weakly or none |\n| Interruption of transmission of virulent virus | More effective | Less effective |\n| Reversion to virulence | Possible | No |\n| Stability at room temperature | Low | High |\n| Excretion of vaccine strain and transmission to nonimmune contacts | Possible | No |\n\nReferences and further readings\n\n- [Understanding Six Types of Vaccine Technologies](https:\u002F\u002Fwww.pfizer.com\u002Fnews\u002Farticles\u002Funderstanding_six_types_of_vaccine_technologies). pfizer.com 25 April 2022.\n- Authors. Levinson W, & Chin-Hong P, & Joyce E.A., & Nussbaum J, & Schwartz B(Eds.), (2020). *Review of Medical Microbiology & Immunology: A Guide to Clinical Infectious Diseases, 16e*. McGraw Hill.\n- [US Food and Drug Administration.](https:\u002F\u002Fwww.fda.gov\u002Fvaccines-blood-biologics\u002Fconsumers-biologics\u002Fvaccines-children-guide-parents-and-caregivers)\n- Sanders, B., Koldijk, M., & Schuitemaker, H. (2014). Inactivated Viral Vaccines. *Vaccine Analysis: Strategies, Principles, and Control*, 45–80. \u003Chttps:\u002F\u002Fdoi.org\u002F10.1007\u002F978-3-662-45024-6_2>","f8df83ce-ec2e-4f36-ab06-3a3a945d3356",[47,55,62,69],{"slug":48,"title":49,"description":49,"author":50,"date":51,"updatedDate":52,"draft":40,"category":41,"tags":53,"image":43,"_id":54},"biopesticides","Biopesticides: Classification, Advantages, and Disadvantages","Alisha Tripathi","2023-09-07","2026-06-24",[],"ff3affd3-f454-4935-889f-ffe09eeb523f",{"slug":56,"title":57,"description":57,"author":58,"date":59,"updatedDate":39,"draft":40,"category":41,"tags":60,"image":43,"_id":61},"microbial-fuel-cells-mfcs-types-components-and-applications","Microbial Fuel Cells (MFCs): Types, Components, and Applications","Ashma Shrestha","2023-08-02",[],"b72fc1ee-f2f9-4357-94c4-1ea7638837c3",{"slug":63,"title":64,"description":64,"author":65,"date":66,"updatedDate":52,"draft":40,"category":41,"tags":67,"image":43,"_id":68},"single-cell-protein-scp-sources-applications-and-advantages","Single Cell Protein (SCP): Sources, and Applications","Samikshya Acharya","2023-07-11",[],"0b3a382d-549e-4e9b-b21c-c127e2905d64",{"slug":70,"title":71,"description":71,"author":58,"date":72,"updatedDate":39,"draft":40,"category":41,"tags":73,"image":43,"_id":74},"microbes-in-art-agar-art-competition","Microbes in Art: Agar Art Competition","2023-06-27",[],"ee0f03c7-4c0c-442b-89f7-754585448f8e",[76,82,88,94,97,100,105,110,114,118],{"slug":77,"name":37,"description":78,"image":79,"body":80,"postCount":81},"acharya-tankeshwar","Editor-in-chief","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Ftankeshwar-acharya-author-microbeonline.jpg","***Tankeshwar Acharya, MSc (Medical Microbiology)***\n\n*Tankeshwar Acharya is an Assistant Professor in the Department of Microbiology at Patan Academy of Health Sciences (PAHS), Nepal, where he has been teaching and practicing clinical microbiology for over 14 years. He is the founder of Microbe Online, one of the leading free microbiology education resources on the web, covering bacteriology, mycology, parasitology, immunology, and clinical laboratory diagnostics written from direct experience in both the classroom and the diagnostic laboratory.*",433,{"slug":83,"name":58,"description":84,"image":85,"body":86,"postCount":87},"ashma-shrestha","SEO Copywriter and Science Communicator\nKathmandu, Nepal","https:\u002F\u002Fassets.microbeonline.com\u002Fauthors\u002Fashma-shrestha.png","Ashma Shrestha holds a Master of Science in Medical Microbiology from the Institute of Science and Technology (IOST), Tribhuvan University, Nepal, where she developed a strong foundation in virology, molecular biology, and diagnostic microbiology.\n\nShe now works as an SEO Copywriter at Resolution Digital, where she combines her scientific training with research-driven content strategy. She is certified in Google Analytics and Google Business Profile (GBP), and brings a data-informed approach to science communication writing content that is not only accurate but structured to reach and serve the students who need it most.\n\nAt microbeonline, Ashma contributes articles primarily in virology and molecular biology, areas she finds most compelling for their mechanistic depth and their growing clinical relevance. Her writing reflects the same standard the site is built on: factual rigor, clear explanation of the *why* behind microbiology concepts, and content that helps students move from memorization to genuine understanding.\n\nShe is passionate about making complex microbiological concepts accessible without sacrificing accuracy; a skill that sits at the intersection of her scientific training and her professional work in content and SEO.",81,{"slug":89,"name":90,"description":91,"image":92,"body":92,"postCount":93},"sushmita-baniya","Sushmita Baniya","Author \u002F Contributor",null,32,{"slug":95,"name":65,"description":91,"image":92,"body":92,"postCount":96},"samikshya-acharya",20,{"slug":98,"name":50,"description":91,"image":92,"body":92,"postCount":99},"alisha-tripathi",6,{"slug":101,"name":102,"description":103,"image":92,"body":92,"postCount":104},"aastha-shrestha","Aastha Shrestha"," Author \u002F Contributor",10,{"slug":106,"name":107,"description":108,"image":92,"body":92,"postCount":109},"guest-author","Guest Author","Guest Author \u002F Contributor",2,{"slug":111,"name":112,"description":91,"image":92,"body":92,"postCount":113},"srijana-khanal","Srijana Khanal",18,{"slug":115,"name":116,"description":108,"image":92,"body":92,"postCount":117},"dr-poonam-acharya","Dr. Poonam Acharya",1,{"slug":119,"name":120,"description":91,"image":92,"body":121,"postCount":122},"nisha-rijal","Nisha Rijal","**Nisha Rijal** is a microbiologist and quality assurance specialist. She served for nearly 12 years as a microbiologist at the National Public Health Laboratory (NPHL), Nepal's national reference laboratory, and continues to work as a consultant microbiologist in international public health organization. ",51]