As a primary care physician, what I think we do best is prevention. One of the greatest prevention strategies we have is vaccinations, so anti-vaccinators are often at odds with my approach to medicine. The anti-vaccine movement is often based on anecdote rather than science and evidence.

The CDC recently announced that the U.S. was headed towards its worse year for whooping cough -- pertussis -- and at question is either the effectiveness of the vaccine or the poor uptake of vaccinations. In the U.S., nearly 18,000 cases have been reported so far, which is more than twice the number seen last year this time.

Whooping cough is highly contagious and yes, it can be deadly. It can affect anyone at any age but the most dangerous group affected are young children. We know, according to the CDC, that vaccination rates for young children are pretty good, but adolescents who require an extra dose to boost their immunity have not been as good at uptake.

What is likely to happen this winter? Well, the writing is on the wall, so to speak. Without boosting the vaccine in the teenage years, whooping cough has been allowed to resurface. What might be a nuisance in adults can be fatal in children as their airways are smaller and easier to become blocked with inflammation. We know that the vast majority of deaths are see in in children under the age of one. It is why caregivers of young children should be vaccinated against pertussis as well. The adult immunization reinforces the concept of herd immunity.

Newer vaccines marketed under the names of Adacel and Boostrix available in Canada are now acellular and as a result, the side effects from the vaccine that used to be seen are pretty much gone.

Acquired immunity to pertussis is reported to wane after 4 to 12 years after vaccination, which is why revaccination is so important. Although pertussis symptoms are often mild or asymptomatic, complications occur in 23 to 28% of adults.

Unprotected adolescents/adults function as reservoirs of infection for:

  • unvaccinated newborns and infants
  • partially vaccinated infants

Studies have demonstrated that in 75-83% of infant pertussis cases, the source of infection is household members (e.g., parents, siblings, grandparents) with parents acting as primary vectors in 55% of cases.

Indeed, there has been a resurgence of reported pertussis cases in recent years. This may be due to:

  • iimproved methods of detection
  • waning of the vaccine in adolescents/adults
  • increase in transmission of infection from adolescents/adults to infants. In 2010 outbreaks in Canada (e.g., British Columbia, Manitoba, Saskatchewan) and US (California with over 8,300 cases and 10 infant deaths).

Global estimates have assumed an overall case fatality rate of 0.04% in developed countries. Our Canadian advisory board on immunization NACI recommends:

  • adolescents 14-16 years: Tdap
  • adults: Td every 10 years with one dose being Tdap

All provinces have Tdap programs for adolescents. Examples of adult Tdap programs recently implemented include:

  • New Brunswick (Jan 2011): Tdap vaccination funded for new parents; recommended for other caregivers
  • Saskatoon (July 2010): Tdap vaccination funded for parents, grandparents, caregivers with infants less than 6 months of age

Be sure you are up to date.