Earlier this summer, the Centers for Disease Control reported that cases of pertussis, or whooping cough, are soaring: 18,000 infections have been reported so far in 2012, which is twice the number seen by this time in 2011. Dr. Anne Schuchat, a director at the CDC, said recently in a briefing: “We may need to go back to 1959 to find a year with as many cases reported by this time.”
In general, about half of infected children under the age of one are hospitalized, and so far this year, nine babies have died. Outbreaks are often blamed on unvaccinated kids. But scientists and public health officials say that in this case, part of the problem may be that the current vaccine (on the market since 1997) doesn’t work as well long-term, since many cases are being seen in vaccinated kids. In Washington state, for example (where an epidemic was declared this spring), over 75 percent of pertussis patients were up-to-date on immunizations. In a letter in the Journal of the American Medical Association this month, Australian researchers support this idea, finding that children who received the current pertussis vaccination are more likely to be infected than those who had the older version. The pre-1997 shot was a “whole cell” formulation and was switched to an “acellular” version, which is more purified form that carries a lower risk of adverse effects after injection.
— Stephanie Precourt
— Carolyn Castiglia
— Melanie Petersen
But even though many of this year’s cases of whooping cough occurred in vaccinated people, typically the course of the disease for them is milder and less often requires hospitalization. So the recent findings are no reason to skip the vaccine — in fact, quite the opposite, says the CDC. To curb the spread of the disease, they are urging that all babies and children still get the pertussis shot and that adults receive boosters, especially pregnant women and anyone who will be around young babies (who, before the age of two months, are too young to be vaccinated themselves). Schuchat reiterates that vaccines are the number one defense against infection, and unvaccinated children are eight times more likely to get pertussis.
For now, most parents heed this advice. Despite the headlines you often see about parents choosing not to vaccinate their kids, or the long-debunked myth that vaccines cause autism, the U.S. has high and steady vaccine rates: at least 90 percent of kids get shots for most vaccine-preventable diseases. In fact, vaccination rates actually increased between 2009 and 2010, and less than one percent of toddlers born between 2007 and 2009 haven’t been vaccinated at all. Keeping these stats up produces “herd immunity“— the community protection that comes when a critical number of people are vaccinated. When vaccination rates fall below a certain level, diseases are apt to spread more rapidly.
Whether rates will stay high remains to be seen, though, due to the current tug of war over just how easy it should be for parents to opt out of required shots for school. In my son’s southern California preschool, for example, a simple parent signature on a form clears kids from required vaccines. California is considering a bill that would make this more difficult (involving a doctor’s consultation instead of just signing a paper), but meanwhile other states that currently have tighter restrictions than California are weighing legislation to make the process less strict.
Still on the fence about school-mandated vaccines? Schuchat tells us a lot of parents take advantage of vaccine exemptions because they think certain diseases are no longer a threat, but in recent years the U.S. has seen formerly low-level diseases spiking among communities where there’s a higher number of parents opting out of vaccinating their kids, such as a measles outbreak that occurred this winter as a result of close quarters at the Super Bowl. Measles used to be considered eliminated in the U.S., but in 2011 there were 222 cases — the most seen in 15 years. The disease is often imported from other parts of the world, where it continues to infect 20 million and kill 200,000 annually. The fact that this disease has disappeared from most kids’ medical records — largely thanks to vaccination — doesn’t mean the threat is no longer there.
We should still have a healthy fear of formerly obscure diseases, say public health officials. Schuchat warns of the current outbreak, “There is a lot of pertussis out there, and I think there may be more coming to a place near you.” Experts warn that if the trend moves toward lower immunization rates, or schedules that vary from the CDC’s recommended one, unvaccinated people — whether by choice, because of age, or for health reasons — will be at higher risk.