What is variolation?
Exposure of individuals to smallpox scabs by inhalation or through open wounds
What is vaccination?
Inoculation of cowpox virus into skin (Edward Jenner)
Why/how does vaccination work?
- Exposure generates a primary immune response producing antibodies and memory B- and T-cells.
- Secondary immune response upon re-exposure is therefore rapid and strong.
- Vaccination is one of the great achievements of modern medicine.
Measles
- Measles is caused by measles virus (paramyxovirus, – strand, unsegmented, enveloped, no animal reservoirs)
- Highly contagious, airborne spread by coughs and sneezes. Complications include blindness, inflammation of brain, pneumonia and death
Measles vaccine
- Highly effective for long-term protection against measles infection
- Live attenuated virus given with mumps and rubella (MMR vaccine) as shot and a booster
Why is vaccination useful?
- For disease prevention in individuals and the public at large
- Useful against viruses for which there are few or no treatments
- Does not require that everyone be vaccinated for it to be effective; herd immunity limits epidemics
- Commonly administered to children and adult travelers
What are the different types vaccines?
-Attenuated whole-agent vaccines (live) MMR, Sabin polio (OPV) -Inactivated whole-agent vaccines (killed) Salk polio (IPV) -Toxoids (inactivated toxins) Tetanus -Subunit vaccines (antigenic proteins or fractions) Acellular pertussis Recombinant hepatitis B SARS-CoV-2 -Conjugated vaccines The antigen is linked to another immunogenic molecule Particularly useful for polysaccharides Effective in children <18 months
What are mRNA vaccines?
- Against SARS-CoV-2 contain an mRNAs for just the Spike protein embedded within a lipid “nanoparticle”.
- The lipid nanoparticle protects the mRNA from degradation until the mRNA gets inside the cell where it can be translated
What is the first type of polio vaccine?
Inactivated whole-agent vaccine (killed): -Salk: Inactivated Polio Vaccine (IPV) 1955 -virus inactivated with formalin -injection, produces IgG in blood -prevents virus spreading to CNS
What is the second type of polio vaccine?
Attenuated whole-agent vaccine (live) -Sabin: Oral Polio Vaccine (OPV) 1962 -mutant “attenuated” virus strains -droplet or sugar cube, gut immunity -provides contact immunity
What is the varicella vaccine?
- prevents chicken pox in children
- can prevent shingles (zoster) in elderly
- no vaccine-associated deaths in 40M doses (safe)
- vaccination not routine in some countries (e.g., UK)
- vaccination required in 41 states in US
What is the HPV vaccine?
-there are more than 150 serotypes of HPV
-90% of genital warts caused by HPV Types 6 and 11
-70% of cervical cancers caused by Types 16 and 18
-Types 16 and 18 cause half of vaginal, vulval, penile, anal and oropharyngeal cancers
-Cervarix vaccine is against Types 16 and 18.
-Gardasil is against Types 6, 11, 16, and 18.
recommended for 11-12 year-old girls and boys
and women to 26 years old
**cervical cancer is one of the few preventable cancers
What is the Haemophilus influenzae type B vaccine (Hib)?
- conjugate vaccine: polysaccharide + protein
- H. influenzae type B causes meningitis
- polysaccharide alone doesn’t work well in children under 18 mos. of age
- conjugate is effective in kids, who have immature immune systems
- herd immunity: giving vaccine to children reduces H. influenza type B infections in adults
- H.i.B polysaccharide fused to either tetanus, diptheria or meningococcal proteins
- Hib vaccine is one of WHO’s Essential Medicines
What is control, elimination, eradication?
-Control: Reduction to an acceptable level
-Eradication: Permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed.
Example: smallpox
-Elimination of disease: Reduction to zero of a disease’s incidence in a defined area.
-Elimination of infections: Reduction to zero of infection in a defined area. Example: polio.
What is extinction?
The specific infectious agent no longer exists in nature or in the laboratory.
Example: none
How was smallpox eradicated?
- First effort was in 1950
- 1980 was declared eradicated
- Jenner first used cowpox in 1792
What are some characteristic to develop new vaccines?
- Must be profitable
- Must be able to culture pathogen
- Recombinant DNA techniques
- Adjuvants
- Deliver in combo
There are no useful vaccines for what?
chlamydias, fungi, protozoa, helminths
HIV*
those against cholera and tuberculosis are not reliable
the easy vaccines may have already been made
What vaccines are still in the experimental stage?
Ebola
-Using AAV or VSV viruses to deliver Ebola
Why are oral vaccines useful?
- easy to admin
- effective for protection at mucous membranes
What is the therapeutic index?
risk vs benefit
Example: OPV sometimes causes poliomyelitis
What is the Global Eradication Initiative?
- Program to eradicate polio primarily funded by Bill Gates
- Has reduced polio incidence of 99%
What is an example of diagnostic immunology?
Koch’s experiment:
-Guinea pigs with TB injected with Mycobacterium tuberculosis: Site became red and slightly swollen
-like the Tuberculin (or Mantoux) test
due to cell-mediated immunity
What is sensitivity?
True positive rate. Probability that the test is reactive if the specimen is a true positive
