Communicating About Adverse Events: Immunisation

STEPS

• First know the facts - rates of adverse events in common vaccines
• Second, have a surveillance system
• Third know how to communicate risk to the media and the press

Why are health staff and politicians frightened of adverse events?

• They generate loss of confidence in the immunization programme
• Staff begin to doubt they are doing the right thing
• Staff change the advice they give to parents

General principles for communication

• All vaccines approved for use are safe
  • None is completely without risk - balance
  • Mild vaccine reactions are common - train for them
  • Adverse events are rare and the rates are well documented - train for them
  • Severe adverse events are extremely rare - promote it

E.g. DTP causes mild side effects very frequently:

Frequency of observed adverse events (almost all received acetaminophen, not controlled) - results of studies of 439 children given 1,296 doses of DPT/IPV vaccine at 2, 4, and 6 months of age:

Local reactions

• Any redness: 36%
• Redness > 2.5cm: 3%
• Swelling > 1.5 cm: 14%
• Swelling > 5 cm: .2%
• Tenderness: 25%

Systemic

• Fever >= 38.5°: 27%
• Fever >= 39.0°: 3%
• Fussiness: 54%
• Increased crying: 34%
• Increased drowsiness: 40%
• Decreased eating: 25%
• Diarrhoea: 9%

General principles

The precise rates of adverse events are difficult to establish because of lack of uniformity of study design and case definitions.

IF...

...a symptom occurs that is compatible with a vaccine reaction after vaccination, do not assume it MUST be due to the vaccine (e.g. cold, fever, convulsion etc.)

...so communicate

• with questions and answers
• ahead of mass campaign
• on a regular basis
• mention rates
• estimate expected numbers for your population
• explain "coincidental events"
• What do they NOT cause
• Other myths

Pertussis

• Generalized reactions
  
  • Fever starts within 12 to 24 hours and lasts less than 24h (>=38°C 1 in 2;> 40.5°C 1 in 100 if no acetaminophen), fussiness, crying, drowsiness, reduced appetite (1 in 5) and vomiting
• Localized side effects (singly or in combination in more than 50% of children, higher rate after the fourth and fifth dose)
  
  • Redness (1 in 3), swelling (2 in 5), pain (1 in 2) and tenderness at the site of injection
  • Lumps
  • Abscess
• Allergic reactions (skin rashes, hives, swelling, anaphylactic shock)
• Inconsolable crying or screaming for more than 3 hours (caused by pain) 1 in 100
• Hypotonic-hyporesponsive episode (after first dose) 1 in 1,750
• Febrile convulsions (rare after first 2 doses, increased risk if family history) 1 in 700 to 1 in 10,000
• Not proven to cause encephalopathy, brain damage, autism, infantile spasms, epilepsy, mental retardation, learning disorders, hyperactivity
• National Childhood Encephalopathy Study there may be a slight increased risk of acute encephalopathy. If risk extremely rare no more than one per million. No risk of chronic disfunction
• No risk of SIDS

Diphtheria

• Fever
• Redness, swelling, pain and tenderness
  
  • Increases with number of doses and dose of toxoid
  • Up to 70% of children with booster dose at 4 to 6 years with local redness and/or swelling of 5 cm or more
  • Booster dose at 14-16 years 10% marked local reaction
  • 7 years and over should get reduced dose (Td)

Tetanus

• Redness, swelling, pain and tenderness.
  
  • Likelihood of local reaction increases with the number of doses given (age).
  • Severity of reaction after booster is related to the concentration of tetanus antitoxin present at the time of injection. Less than 2% of booster doses most severe if more than one every ten years
• Swollen lymph glands, fever, headache and muscle aches
• Severe allergic reaction (1 in 100,000?) and rare anaphylaxis
• Neurological reactions -peripheral neuropathies (Paralysis and change in sensation, 1 in 1,000,000?)

Polio Vaccine

Oral Polio Vaccine

• Vaccine-associated paralytic polio
  
  • 1 in 1.3 million first doses
  • 1 in 6.9 million subsequent doses
  • contacts 1 per 20 million doses
• No increased risk of GBS

Inactivated Polio Vaccine

• Minor pain and redness

SV40?

Haemophilus influenzae type b

• Fever of more than 38.3°C and localized redness and swelling reported
• When separate, local redness and pain in 5-15% of infants (milder and less common than after DTP)
• DTP/Hib combo same as DTP
• A few severe allergic reactions

Measles

• Fever > =39.4° 2% in 8 to 10 days after and lasts 24 to 48 hours
• Febrile seizures (1 in 3,000 doses)
• Rash and conjunctivitis 2%
• Encephalitis 1 per million
• Thrombocytopenia 1 per 30,000
• Allergic reactions including anaphylaxis 1 per 100,000 to 1 per million
• Less after second dose
• Not SSPE, not autism, not Crohn's disease

Mumps

• Parotitis and low grade fever
• Febrile seizures
• Aseptic meningitis (15 to 35 days after vaccination, no sequelae)
  
  • Jeryl Lynn (low or no risk) versus Urabe and Leningrad-3 (1 in 1,000-60,000)
• Allergic reaction (including rash, pruritus and purpura) but uncommon, brief and mild

Rubella

• Frequency and severity increase with age in susceptible individuals
• Rash and lymphadenopathy occur occasionally
• Transient pain in joints 7 to 21 days after vaccination (less than 1% of children versus 1 in 4 adult female). Mostly in postpubertal females. Arthritis in only 10% of these. Still debated.
• Thrombocytopenia
• Anaphylactic reaction rarely

Hepatitis B

• Pain and tenderness in 15% (3%-29%) of vaccinations and fever > 37.7°c in 1%-6%
• Fever, headache, muscle aches and pain, nausea, vomiting, loss of appetite, and fatigue occur at same rate as in placebo
• Allergic reactions around 1 per 1,000, anaphylactic reaction 1 per 600,000 doses
• Cases of rheumatoid arthritis and demyelinating diseases of central nervous system (multiple sclerosis) reported but no causative link demonstrated
• No association with GBS

BCG

• More common in young infants and frequently related to improper administration techniques
• Persistent or spreading skin ulceration at vaccination site, inflammatory adenitis and keloid formation
• Marked lymphadenitis or suppurative adenitis occur in 0.2 to 4.0 per 1,000 vaccinees
• Disseminated BCG infection including severe osteomyelitis can be fatal (1 per million).
• Almost exclusively in severely immuno-compromised

Pertussis Results of large US study

Summary

• Communicating about adverse events and vaccine safety does not alter vaccine safety
• Communication alters the PERCEPTION of vaccine safety
• Communication alters the PUBLIC REACTION to an event

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