UKPCS Science Life Sciences-Microbial_infection- Elementary knowledge of vaccines: #44

Elementary knowledge of vaccines:

The word “vaccine” originates from the Latin Variolae vaccinae (cowpox), which Edward Jenner demonstrated in 1798 could prevent smallpox in humans. Today the term ‘vaccine’ applies to all biological preparations, produced from living organisms, that enhance immunity against disease and either prevent (prophylactic vaccines) or, in some cases, treat disease (therapeutic vaccines). Vaccines are administered in liquid form, either by injection, by oral, or by intranasal routes. Vaccines are composed of either the entire disease-causing microorganism or some of its components.


Vaccines may be constructed in several ways:

  • From living organisms that have been weakened, usually from cultivation under sub-optimal conditions (also called attenuation), or from genetic modification, which has the effect of reducing their ability to cause disease;
  • From whole organisms that have been inactivated by chemical, thermal or other means;
  • From components of the disease-causing organism, such as specific proteins and polysaccharides, or nucleic acids;
  • From inactivated toxins of toxin-producing bacteria;
  • From the linkage (conjugation) of polysaccharides to proteins (this increases the effectiveness of polysaccharide vaccines in young children).
Type of vaccinesExamples
Live-attenuatedMeasles, Mumps, Rubella, Varicella zoster
InactivatedHepatitis A, Influenza, Pneumococcal polysaccharide
Recombinant sub-unitHepatitis B
ToxoidTetanus, Diphtheria
Conjugate polysaccharide-proteinPneumococcal, meningococcal, Haemophlius influenzea type b (Hib)



Vaccine-preventable diseaseType of diseaseType of vaccineYear vaccine developed Most common severe disease outcomes
Smallpoxvirallive attenuated1798disfiguring, sometimes fatal
RabiesviralInactivated, inactivated (cell culture)1885always fatal
Typhoidbacterialinactivated intestinal

live attenuated polysaccharide  protein conjugate





intestinal haemorrhage and perforations, encephalitis, psychosis, abscesses of internal organs, sometimes fatal
Cholerabacterialinactivated (injectable) inactivated and recombinant protein (oral) inactivated (oral)1896



life- threatening dehydration, electrolyte imbalance, sometimes fatal
Plaguebacterialinactivated1897seizures, coma, internal bleeding, fatal within four days if not threate.
DiphtheriabacterialToxoid1923choking, heart and kidney failure, facial or swallowing or respiratory paralysis, sometimes fata
TetanusbacterialToxoid1926severe muscle spasms and bone fractures, lockjaw, respiratory distress, sometimes fatal
Pertussisbacterialinactivated purified protein*1914


choking in young infants, rib fractures, hernias, incontinence, ruptured blood vessels, sometimes fatal
Tuberculosisbacteriallive attenuated1921coughing blood, abscesses of internal organs or bone, meningitis, sometimes fatal
Yellow fevervirallive attenuated1932liver damage, internal bleeding, sometimes fatal

live attenuated



 life-threatening pneumonia, worsening of coronary heart disease, extreme muscular fatigue or aches, high fever, sometimes fatal
Polioviral inactivated

live attenuated



respiratory paralysis, life-long paralysis of limb(s), skeletal deformity, sometimes fatal
Pneumococcalbacterial23-valent polysaccharide;

protein conjugate



pneumonia, meningitis, ear infections, infections of bone and heart muscle, protein conjugate sometimes fatal

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