Research has revealed a new explanation for the pattern of whooping cough outbreaks in the US as the disease is expected to hit certain areas of the country especially hard this spring.
For years experts have blamed a low-quality vaccine for spikes in the disease, which can be deadly when contracted by infants.
However, a report released Wednesday by the University of Michigan suggests that the surges are actually explained by the the age that children go to school and have higher contact with each other, making them more likely to contract it and pass it on.
The researchers found that vaccinating children and teens brought the rates for infant pertussis down by 25 percent.
A report published Wednesday from the University of Michigan suggests the pattern of whooping cough outbreaks can be explained by the age children enter school
Whooping cough is an infectious disease that is rarely serious in adults but can cause fatal complications in infants and children who haven’t yet received all of their vaccinations.
Also known as pertussis, the disease named for the distinctive ‘whoop’ noise patients make after a cough is responsible for 195,000 infant deaths each year worldwide, mostly in the developing world.
There were 17,972 reported cases in the United States in 2016, including six infant deaths, according to the CDC.
The study released Wednesday identified primary school children and teenagers as the group most-responsible for spreading the disease and found that booster vaccinations focused on groups of children ages five to 10 and 10 to 20 resulted in a drop in infant cases of about 25 percent.
‘The overwhelming amount of transmission is happening in those age groups,’ Aaron King, an infectious disease ecologist and applied mathematician at Michigan and one of the authors of the study, said. ‘So, we have to make sure that kids are getting vaccinated before they go to school. That’s going to have the biggest impact.’
The goal of the study published Wednesday in Science Translational Medicine was to determine the causes of the resurgence of whooping cough that began in the mid-1970s, which has commonly been attributed to a low-quality vaccine which critics say wears off after five to seven years.
However, the study’s findings, based on data from pertussis records in Massachusetts from 1990 to 2005 to and, revealed the vaccine is actually highly effective.
‘Conventional wisdom is that the current vaccine is the problem, but that’s not consistent with what we see,’ King said.
The current vaccine was found to provide lifelong protection to 55 percent of people and protect 90 percent of people for more than a decade.
The goal of the study published Wednesday in Science Translational Medicine was to determine the causes of the resurgence of whooping cough that began in the mid-1970s
With this in mind the researchers delved further into the history of the disease for a better explanation.
Before the whooping cough vaccine was introduced in the 1940s, the majority of children were exposed to the bacterium that caused it, Bordetella pertussis, and their immune systems reacted by building up long-lasting immunity to it.
When the vaccine was introduced, incidence went down 100-fold because children were being vaccinated and most American adults were immune, resulting in what the researchers refer to as a honeymoon period.
Through the following decades there was an increase in the number of susceptible adults, some who had not received the vaccine as children and others who had received it but the effectiveness had worn off because the vaccine, while effective, was imperfect.
At the same time the generations of adults who had developed immunity were dying out, which the researchers refer to as ‘demographic turnover’.
The researchers concluded that the second scenario, waning vaccine effectiveness over time, had combined with incomplete vaccinations and steady demographic turnover combined to bring the honeymoon period to an end.
‘This resurgence is the predictable consequence of rolling out a vaccine that isn’t quite perfect and not hitting everybody in the population with that vaccine,’ King said.
They also concluded that even vaccinating everyone in the population perfectly would not be enough to eradicate the disease, contrary to what the Centers for Disease Control and Prevention has said in the past.
‘Our results are important because they show that recent trends in pertussis are not necessarily caused by recent changes in epidemiology or biology,’ lead author Domenech de Celles said.
‘Rather, the contemporary epidemiology of pertussis may be interpreted as a legacy of longstanding immunization practices.
‘It’s an important shift of perspective, which makes pertussis a complex but exciting system to study.’