In an Ontario, Canada study published on Monday in the Canadian Medical Association Journal, researchers found that by the time a child reaches the age of seven, the vaccine’s effectiveness has decreased significantly.
Dr. Natasha Crowcroft, chief of applied immunization research for Public Health Ontario, says that the vaccines currently in use offer good protection for several years after the first immunizations are given, “So it’s good news for protecting babies.” But she says that by the time a child is seven or eight, there is little immunity left, reports CTV News.
Pertussis, commonly called whooping cough is a highly contagious bacterial infection that affects the respiratory tract and is quite often marked with a severe, hacking cough followed by a sharp intake of air that creates a noise similar to a high-pitched “whoop.” It is especially difficult to watch an infant trying to cough and they sometimes appear to stop breathing.
Before the start of Canada’s pertussis vaccination program, the incidence of pertussis was around 156 cases per 100,000 people. Since that time, the incidence of pertussis has ranged from a low of two per 100,000 in 2011 to 13.9 in 2012.
Canada has used the “acellular” vaccine (ACV) since 1997. Before that time, Canada used the whole cell vaccine (WCV), and like other developed nations, Canada changed over to the ACV because of the side-effects.
But the recent Canadian study has turned up an interesting new finding. “We found something that’s quite new, which is that people in our study who had their very first dose of vaccine that was the whole-cell vaccine — the old-fashioned style of vaccine — as a baby, they seemed to get longer-lasting protection,” said Crowcroft.
It was also noted that subsequent immunizations were the acellular type. The researchers also found that if children were started out with the ACV during their first three immunizations, they were twice as likely to develop pertussis as those people who had started out with the WCV when they were infants.
Digital Journal reported on a study published in December 2014 that found that parts of the bacteria in the vaccine that “primes” the immune system to recognize and fight pertussis had changed.
At that time, researchers noted that the evolution taking place in the Bordetella pertussis bacterium started before the U.K. and U.S. switched from using the whole cell (WCV) vaccine to the acellular ACV vaccine in 2004.
The Canadian researchers are recommending that the current pertussis vaccination strategy needs to be changed or updated. This could include immunizing women during pregnancy, reintroducing the whole cell vaccine for infants, or introducing additional pertussis vaccination booster shots for older children and adults.
This recommendation makes a lot of sense, considering the U.S. Centers for Disease Control and Prevention (CDC) has finally acknowledged that the effectiveness of the acellular vaccine was waning. As a matter of fact, the CDC reported that during 2014, 32,971 cases of pertussis were reported. This represents a 15 percent increase compared 28,639 cases reported during 2013.
