Vaccination / Immunisation

Introduction

Objectives

• Briefly explain how vaccines work.

• Give a brief overview of the history of vaccines.

• Give a brief overview of the controversies surrounding Pertussis and MMR vaccines.

• Briefly explain what is meant by the primary and secondary immune response.

• Compare and contrast natural active, natural passive, artificial active and artificial passive immunity.

Vaccination

Vaccination is the administration of a vaccine to produce immunity to a disease

• Immunity develops in response to the administration of either dead or living (but artificially weakened) microbes (vaccines) or deactivated toxins (toxoids).

• The vaccines and toxoids retain the antigenic properties that produce immunity but should not cause the disease.

Vaccine

The material administrated may be a weakened or inactivated form of the pathogen.

First Vaccinations

• Smallpox was the first disease people tried to prevent by inoculating themselves with other types of infections

• Smallpox inoculation was started in China (or India) before 200 BC

Vaccination• In 1796 Edward Jenner inoculated

using cowpox (a mild relative of the deadly smallpox virus). The word vaccination was first used by Edward Jenner.

• Vaccination (Latin: vacca = cow) is so named because the first vaccine was derived from a virus affecting cows—the relatively benign cowpox virus—which provides a degree of immunity to smallpox.

Vaccination Initiatives

An 1853 law required universal vaccination against smallpox in England and Wales, with fines levied on people who did not comply.

Many modern vaccination policies allow exemptions for people with:

compromised immune systems,

allergies to the components used in vaccinations,

or strongly-held objections.

Herd Immunity

Vaccines have contributed to the eradication of smallpox. Other diseases such as rubella, polio, measles, mumps etc, chickenpox, and not as common as they were a hundred years ago

As long as the vast majority of people are vaccinated, it is much more difficult for an outbreak of disease to occur, let alone spread. This effect is called herd immunity

Objections

Vaccination policies may be met with resistance from some groups and individuals in society.

Why may people object to vaccination policies?

Objections!!

Reasons for Objections

Ethical reasons Political reasons

Medical safety Not effective

Religious beliefs

Compulsory vaccination = excessive government intervention

(Medical opinion is that the benefits of preventing suffering and death from infectious diseases greatly outweigh the risks of adverse effects following immunization)

Pertussis

‘A 1974 report ascribed 36 reactions to whooping cough (pertussis) vaccine, a prominent public-health academic claimed that the vaccine was only marginally effective and questioned whether its benefits outweigh its risks, and extended television and press coverage caused a scare.

Vaccine uptake in the UK decreased from 81% to 31% and pertussis epidemics followed, leading to deaths of some children.

Mainstream medical opinion continued to support the effectiveness and safety of the vaccine; public confidence was restored after the publication of a national reassessment of vaccine efficacy.

Vaccine uptake then increased to levels above 90% and disease incidence declined dramatically.’

MMR vaccine

In the UK, the MMR vaccine was the subject of controversy after publication of a 1998 paper by Andrew Wakefield, et al., reporting a study of 12 children mostly with autism spectrum disorders with onset soon after administration of the vaccine. Wakefield suggested that giving children the vaccines in three separate doses would be safer than a single vaccination.

This suggestion was not supported by the paper, and several subsequent peer-reviewed studies have failed to show any association between the vaccine and autism.

Primary and Secondary Responses

Primary responseFirst exposure to pathogen, immune response insufficient to combat disease.Latent period of 5-10 days before measurable amounts of specific antibodies appear in blood.Secondary responseSubsequent exposure to same antigen.Antibody production is much more rapid (Max. antibody conc. reached in < 2 hrs).

The student nurse

Helen is 26 and has just started her nursing degree. She has been advised that she will need a course of Hepatitis B vaccinations. She is not very happy about this as she believes that vaccinations may have adverse effects on health and well being and anyway, she is fit and healthy, and should not have to worry about picking up infections from patients.

Questions

How might she be at risk of Hepatitis B infection?• Needle stick and other Nosocomial transmission

(exposure to blood of infected persons).Is the onset of Hepatitis B infection rapid or

insidious?• Insidious.What might chronic Hepatitis B infection lead to?• Cirrhosis or hepatocellular carcinoma.Is she right in thinking that her youth and health

will protect her?• No, but Universal Precautions will offer a certain

amount of protection.

Questions

What is the general aim of immunisation?• To make an individual produce a primary response

without getting the disease. Then, when they do come across the disease, they will produce a secondary response, and combat the disease very rapidly.

How would you explain to Helen how vaccines work?

• Vaccines stimulate her immune system to produce protective antibodies. The protective antibodies (and /or memory cells) produced in response to the vaccine then remain in her body to tackle that particular pathogen, should that pathogen enter her body in the future.

Questions

Can she refuse to have the injections?• Yes, but ……

Why are 3 injections usually necessary?• To ensure adequate levels of antibody to protect

against Hepatitis B.

What sort of immunity is this?

a) Natural active b) Natural passive

c) Artificial active d) Artificial passive

Is the immunity in this case long or short term?Long Term

The school child

Craig is 5 years old and has just started school. He has developed a rash with obvious vesicles (small blisters), his temperature is 380C and he is generally unwell and a bit irritable. His mother reports that he has had all his necessary immunisations.

Questions

What organism is likely to have caused his condition?a) Varicella (Chicken Pox) b) Rubella (German

Measles)c) Rubeola (Measles) d) Small pox

How is this organism transmitted?• Respiratory secretions and lesion (vesicle)

secretions.Where is he most likely to have picked up the

infection?• School?Why are antibiotics an ineffective treatment option?• Antibiotics are not effective for viral infections.

Questions

Does the fever (pyrexia) have any useful function in this case?

• Possibly increases his immune response.Why then are anti-pyretics a good idea?• Danger of fever induced fits.Will he be able to get this infection again?• In theory, no.What sort of immunity is conferred by getting the

disease?a) Natural active b) Natural passivec) Artificial active d) Artificial passive

Is the immunity in this case long or short term?• Long term.

The new born baby

Megan was born 7 days ago via a normal delivery. Her 17 year old mother, Zoe, has been breast feeding since the birth, but is finding it very uncomfortable. In addition, the baby seems to want to feed every 2 hours and Zoe thinks that her baby is not getting enough milk. She wants to discontinue breast feeding.

Questions

What advice would you give Zoe regarding the benefits of breast feeding?

• As well as the nutritional advantages of breast milk, the colostrum (produced for the first few days after delivery) contains maternal antibodies.

How else does the baby receive maternal antibodies?• Via the placenta.What sort of immunity is Megan being given by Zoe?

a) Natural active b) Natural passivec) Artificial active d) Artificial passive

Is the immunity in this case long or short term?• Short term

The elderly individual

Victor (aged 82) cut his hand whilst doing some gardening. He wiped the wound with a wet tissue and applied a dressing and bandage himself at home. He thought this was sufficient, but when his granddaughter visited him two days later, she insisted on taking him to A and E. He admitted he couldn’t remember the last time he had a tetanus injection, but he thinks it was more than 20 years ago (he doesn’t like going to the GP). The wound is quite deep and looks dirty (it is still contaminated with soil) and is looking a bit inflamed.

Questions

What spore forming organism from the list below might have contaminated his wound?a) Clostridium tetani b) Salmonellac) Chlamydia d) E.Coli

How is this organism transmitted?• Spores of C. tetani are introduced into a puncture

wound, burn or needle stick injury by contamination with soil, dust or faeces. Under aerobic conditions in the wound, spores germinate into vegetative C. tetani cells which produce the exotoxin (tetanospasmin).

Which muscles are particularly affected by this organism?

• Jaw and neck muscles.

Questions

Why might he need an injection of Tetanus immune globulin rather than Tetanus vaccine?

• It will work immediately. A booster tetanus vaccine might take too long to in this case.

What sort of immunity is this?a) Natural active b) Natural passivec) Artificial active d) Artificial passive

Is the immunity in this case long or short term?

• Short term

MCQ’s

In 3 hours single bacterium that divides every 20 minutes will produce:-a) 9 offspring b) 32 offspringc) 512 offspring d) 1024 offspring

The term for ‘hospital acquired’ (from another patient, staff or environment) is:-a) Nosocomial b) Pathogenic c) Resident d) Transient

Organisms that will cause disease are known as:-a) Nosocomial b) Pathogenic c) Resident d) Transient

MCQ’s

The treatment which achieves only killing of non-sporing or vegetative micro-organisms is:-a) Disinfection b) Autoclavingc) Sterilization d) Irradiation

A treatment which achieves the complete killing or removal of all types of micro-organisms, including spores is:-a) Hand washing b) Sterilizationc) Disinfection d) Irrigation

Active Immunity

NATURAL ARTIFICIALImmunity from getting the Immunity from being disease vaccinated

Individual makes own antibodies Individual makes own

(therefore ‘active’) antibodies (‘active’) Confers ‘long term’ immunity ‘Long term’ immunity

Passive Immunity

ARTIFICIAL NATURAL

Receiving injection of Baby receiving immunoglobulin's

Immunoglobulin's in breast milk

Recipient receives ‘ready made’ antibodies

Does not make own antibodies, therefore ‘passive’

Immunity conferred is only short term

Dog with rabies!