Mod. 20 Vaccinations

History of Vaccination

Edward Jenner

Hypothesis - cow pox protected the women from smallpox

Experiment

• Inoculated people

• Reinoculated ones with small pox

• People did not get small pox

Immune system basics

With time body detects non-self and makes antibodies to bind to virus so they cannot infect our cells

B-cells make antibodies - each B-cell makes a different one

Some cells act as memory cells when they “see” the antigen

If EXACT antigen enters again, you get quick antibody production - you do not get disease.

What is a vaccine?

Nontoxic antigens (Ag) injected or ingested to induce artificial specific defenses

Can be life long

Prevent the disease from occurring

Types of vaccines

Inactivation/killed whole microbe vaccine

Live attenuated vaccine

Subunit vaccine

Toxoids

Polysaccharide vaccines

Nucleic acid Vaccine

Inactivation/killed whole microbe vaccine

Inactivate the organism with formaldehyde or heat

Body does not have as large a response to dead/inactivated microbes

May carry other substances like LPS

• DPT — Bordetella pertussis caused side effects

  • Discomfort at injection site

  • Not long lived

Inactivated polio vaccine - injected more than once (boosters)

Influenza (injection)

Live attenuated vaccine

Mutated strains used that are less virulent and no longer cause disease

Long immunity, may not need boosters

Can cause the disease in the immunocompromised and a small % of rest of population

Oral polio vaccine - single dose (Not used in US)

MMR

Subunit vaccines

Single antigen (Ag) or Mixture of Ag

• Must be administered more than once

• Used when whole-agent vaccines are dangerous or cause the wrong response

Recombinant vaccine - type of subunit (HPV, Hepatitis B vaccines)

• Other microbes are engineered to produce the desired ag

Toxoids

Needs a fast response from toxins

• Don’t show signs or symptoms

Inactivated toxins

Few side effects

DPT

Polysaccharide Vaccines

Not as immunogenic as proteins

Conjugate vaccine - bind the polysaccharide to a protein (toxoid)

Mostly used for pneumoniae causing bacteria (meningitis)

Nucleic Acid Vaccine

Injected nucleic acid into cells

Your cell makes the protein which causes the immune response

Influenza and HIV - DNA/experimental only; COVID 19 - mRNA

Herd Immunity - importance

Thresholds for herd immunity vary by vaccine

• Diphtheria - 85%

• Pertussis - 92-95%

• Polio - 80-86%

• Measles - 85-96%

• Mumps - 75-86%

Wakefield study

Used study of 12 patients (very small)

Parents funded the experiment since their kids were harmed

License to Practice Medicine stripped in 2011

Acted dishonestly and irresponsibly in failing to disclose how patients recruited for the study

No scientific evidence to support claims

People tried to link end of MMR series and autism

• thimerosal was eliminated but autism is still climbing

Effect today on wakefield study

MMR vaccine rates were 92% but dropped to below 80%

By 2008 there were 1348 cases and 2 deaths confirmed

US has around 600 cases of measles.