Pertussis, or better known as whooping cough, is a disease that causes severe, almost uncontrollable coughing. Waning immunity in adults caused a resurgence of the disease in the U.S. where up to 2,520 cases (37.5 cases per 100,000 residents) were reported in the first half of 2012. This represents an increase of 1,300% compared with the same period in 2011 and is officially recognised as the worst outbreak in the U.S. in over a half century. We, in Malaysia, have not been spared the same fate. The only difference is that most cases of prolonged cough go undiagnosed here.
Booster shots are vital
One of the main reasons for the pertussis outbreak in a medically advanced nation like the U.S. is due to waning immunity. Most children in the U.S. are immunised with a five-dose series of the Diptheria- Tetanus-acellular Pertussis (DTaP) vaccine starting at two months of age. The protective effects of the DTaP vaccine will typically last between four and 12 years. This means that in the worst case scenario, children aged five years old are already at risk of pertussis if their immunity wears off.
Findings from three different studies in the U.S. on pertussis outbreaks (e.g. pertussis epidemic, 2010. The Journal of Pediatrics 2012) have all pointed to the same conclusion; regardless of the initial effectiveness of the vaccine, there is a period (ages seven to 12 and 11 to 14) during which there appears to be a gap in the immunity provided. This “gap” in protection can be covered by giving the Tdap (Tetanus with lower doses of diphtheria and pertussis antigens) vaccine to teens and adults. The current practice in Malaysia is to give dT (double antigen consisting of diphtheria and tetanus antigens) at school age. A change to Tdap will prevent the circulation of the pertussis bacteria, Bordetella pertussis, in addition to providing boosters for tetanus and diphtheria.
Protect your child
The best way to protect against whooping cough is to make sure your child gets vaccinated, not only with the mandatory DTaP combination vaccine, but also with Tdap booster shots when he or she grows older. As the Tdap vaccine is not mandatory, there is a need for parents and caregivers of children to be constantly reminded of the importance of this booster shot. This will eliminate possible complications due to pertussis like pneumonia, convulsions, apnea, encephalopathy (disease of the brain) and death.
These are crucial for protecting children during the immunity-gap period. At the present moment, a Tdap vaccine for teenagers and adults who are in contact with babies too young to be vaccinated will help to control the cycle of transmission.
Adults need Tdap boosters too
Besides children, it is important that parents and all adults or adolescents in close contact with children be vaccinated against pertussis. This helps to prevent the spread of pertussis to others who have not yet been immunised against it. Even if you have been fully vaccinated during your childhood and schooldays, you will still need a booster shot to strengthen your body’s immunity against the disease. The Tdap booster shot is recommended for anyone aged 11 to 64 years.
The resurgence of pertussis in the United States is a reminder of the importance of maximising your immunisation coverage. The US 2012 pertussis epidemic is a grim reminder of the importance of booster shots and why it should be taken seriously. A recent study showed that children who had not gotten the DTaP vaccine were 23 times more likely to get whooping cough than children who had. We need to do the same in Malaysia as there have been cases of pertussis detected among children and adults with prolonged paroxysmal cough.
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