As the world celebrates the imminent arrival of several COVID-19 vaccines, we might ask how many diseases are preventable by vaccines as of 2020.
Which diseases haven’t got a vaccine yet?
Of the 361 generic infectious diseases that affect humans, only 62 (17%) are preventable by vaccines. Over 100 of the remainder are caused by fungi and parasites – from malaria to scabies, and from ringworm to candidiasis. The process of developing vaccines against these kinds of pathogens is more complicated than working with viruses or bacteria, but scientists are making good progress.
Hope on the horizon
Other notable diseases awaiting vaccines are caused by viruses, such as HIV, Chikungunya, Norovirus, and Zika virus, and bacteria – syphilis, leprosy, and bacillary dysentery. These diseases affect many millions of people each year, incurring significant treatment and care costs for those affected and for society as a whole.
The good news is – most of these diseases already have vaccines in development. Preventing any one of the mentioned diseases would be a huge success and help ease the global strain on healthcare professionals, supplies, and equipment.
The burden of proof and regulation of vaccines can take years of evidential trials, funding allocation, and medical board approval (FDA in the United States), which make progress appear painfully slow. But these processes are necessary to ensure what putting into our bodies is safe and effective.
We remain grateful for the hard work of scientists in developing vaccines to keep us safe.
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What is the difference between antigen vs antibody, and what role do they play in creating an effective vaccine? With the recent focus on the development of a COVID-19 vaccine there has been much talk of antigens and antibodies, often interchangeably, and little clarity on what they are – or the role they play in creating an effective vaccine. In this blog, we’ll cut through the jargon and discover the facts together.
An antigen is any substance or organism that is unrecognized by our immune system. It could be anything from bacteria to chemicals, to viruses … or even foods . Antigens typically trigger an immune response, which may consist of an antibody (more on that later), and are classified by their origins :
Exogenous: entering from outside the body
Endogenous: generated from within
Autoantigens: proteins targeted in autoimmune diseases
Neoantigens (or tumor antigens): resulting from tumor cells.
Native antigens: An antigen which will later be processed by an antigen-presenting cell
In some cases, these main types have subtypes – but we won’t get into an immunology lecture today. An antigen-presenting cell is a cell that processes and then presents the antigen to T-cells (a form of white blood cells), which can then ‘handle’ the antigen, often by killing the offending cell .
Your immune system has “memory” which allows the system to deal with the offending antigen much more quickly and efficiently the next time it is encountered. Vaccines are designed to simulate that first encounter with an antigen and create a robust memory in case the offending agent reappears in the future. .
The importance of vaccines is covered in more detail here, but in short, antigens themselves are crucial in the development of vaccines. Generally, the vaccine consists of a potentially hostile antigen, in a very weak or inactive form.
Antibodies are proteins that bind with the antigen in order to neutralize the latter – or make other elements of the immune system “aware” of their presence. Antibody-producing cells are specifically designed to tackle one type of antigen; and your blood, bone marrow, lymph glands, and spleen will contain millions of them to ensure that every known antigen will be confronted by a corresponding antibody .
Antibodies are secreted by B leukocytes (a form of white blood cell) and circulate in blood plasma either freely or attached to the surface of a B cell. The B and T cells work in unison to identify and locate antigens, create the correct antibodies, and capture (kill/neutralize) the antigen .
A vaccine, by exposing the immune system to a new antigen, will “teach” antibodies the correct format in which to capture or tag that antigen. When the actual disease antigen later enters the body, the immune system will rapidly respond with minimal discomfort and inconvenience.
Effective vaccination needs both
To summarize – an antigen is a disease agent (virus, toxin, bacterium parasite, fungus, chemical, etc) that the body needs to remove, and an antibody is a protein that binds to the antigen to allow our immune system to identify and deal with it.
Don’t take this all for granted, though. As impressive as our immune system is, it’s far from perfect and needs our assistance to prevent harmful antigens from entering the body – through hand washing, face masks, and social distancing. Look after your body and it will look after you!
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 T. Kambayashi and T. Laufer, “Atypical MHC class II-expressing antigen-presenting cells: can anything replace a dendritic cell?”, Nature Reviews Immunology, vol. 14, no. 11, pp. 719-730, 2014. Available: 10.1038/nri3754
 A. Abbas, A. Lichtman and S. Pillai, Cellular and molecular immunology, 9th ed. Philadelphia: Elsevier, 2018, p. 97.
 C. Janeway, Immunobiology 5: the immune system in health and disease, 5th ed. Garland Publishing.
 L. Borghesi and C. Milcarek, “From B Cell to Plasma Cell: Regulation of V(D)J Recombination and Antibody Secretion”, Immunologic Research, vol. 36, no. 1-3, pp. 27-32, 2006. Available: 10.1385/ir:36:1:27
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This edition incorporates all content added since publication of the last series. Country-series eBooks now include the vaccination schedules for every reporting country as an extra chapter.
Additionally, four new volumes have been added to the series.
One of the most important functions of GIDEON is to help users prepare scientific articles, teaching material and other publications (see the Fingerprint case of the month). A new feature now allows users to create custom-designed charts which compare the features of two or more diseases, drugs or pathogens.
For comparison of key clinical and epidemiological features of infectious diseases, in the Diseases tab, click on a disease (step 1 in the image below), and – while holding down the control button – click on other diseases of your choice. Now click on the Compare button (step 2).
We’re continuing our progress in making it easier to find the information you’re looking for in GIDEON with minimal effort. We have added a new feature in the Microbiology module that link relevant organisms to their drug susceptibility and appropriate vaccines as demonstrated by the highlighted links in this screen shot of the Vibrio Cholerae general tab:
These new links are in addition to links added in the past connecting between disease organisms to microbiology and typical therapy to drugs, vaccines and pathogens.
For example see the links from the Anthrax disease general information tab screen shot below, to the Microbiology organism (Bacillus anthracis), Therapy (eg: Ciprofloxacin) and Anthrax vaccine:
GIDEON has always emphasized ease of use by allowing complete usage without any need for a keyboard by only using a mouse. Today we broke our rule to enable text search through GIDEON. As search has become more popular, it has become the user experience many people feel comfortable with when using the web.
Search will initially display results from our Epidemiology and Therapy modules and will extend to all content in GIDEON, including Diagnosis. See how easy it is to search with GIDEON.