“Just because you need a third dose doesn’t mean the two dose schedule is having issues or anything”
Filed under: CDC Watch, News, Opinion, Parents' Pages, Vaccine/Disease Analysis
Because of continued spread, health authorities working with communities in Orange County are giving schoolchildren a third dose of the MMR vaccine. Gallagher says it will be two or three months before it’s known whether the effort succeeded.
Why do they need a third dose?
The infections happened despite high coverage with the measles-mumps-rubella (MMR) vaccine. Among patients ages 7 to 18 — the age group that had the most cases — 85% of patients had received the two recommended MMR vaccine doses.
This doesn’t mean the MMR vaccine isn’t working, says epidemiologist Kathleen Gallagher, DSc, MPH, the CDC’s team leader for measles, mumps, and rubella.
“Two doses of mumps vaccine is believed to be 90% to 95% effective,” Gallagher tells WebMD. “But that means people can still get mumps. If the vaccine is 90% effective and 100 people are exposed to mumps, 10 will get the disease.”
If we imagine that mumps is being sprinkled from the sky and spread evenly throughout the population, then yes, one out of ten vaccinated people would catch mumps if the vaccine was, indeed, 90% effective, or one out of twenty if it were 95% effective. But if the vaccine creates “herd immunity” then the disease shouldn’t be able to jump from vaccinated person to vaccinated person to vaccinated person.
In related news the former Deputy Secretary of Health and Human Services said yesterday:
When I served at the Department of Health and Human Services, we found that the anti-vaccine forces had so demonized the Centers for Disease Control that CDC messages on vaccines had been significantly devalued. As a result, senior officials up to and including the Secretary of HHS had to spend precious time better directed elsewhere fighting back against anti-vaccine messages because of the skepticism with which CDC messages were received.
My goodness! Skepticism? Frankly, the problem seems to be a lack of accuracy in the messages, not skepticism amongst the public. For example during the 2006 epidemic, the CDC said:
During the outbreak in 2006, when many mumps cases occurred in those who had been vaccinated, two doses of the vaccine were estimated to be 79% – 88% effective in preventing mumps.
At that rate, 12 to 21 people out of every 100 vaccinated with two doses would be coming down with the mumps.
Today, in 2010, the CDC spokesperson is saying that the mumps vaccine is 90 to 95% effective. If doubly mumps-vaccinated people are transmitting mumps from vaccinated person to vaccinated person to vaccinated person, how is the mumps vaccine considered to be 90-95% effective? How is herd immunity functioning here?
Why, in 2006, was the CDC saying that two doses of the the mumps vaccine was 79 – 88% effective?
The CDC wants to be trusted, yet flip-flops on the effectiveness of the mumps vaccine depending on which story they spin. How does the CDC expect to inspire public confidence in anything of real significance when their messages are not in line with the science? Why is the CDC surprised that the public doesn’t believe that CDC’s other science is anything more than selective publication of research to suit their changing stories?
If the CDC wants to be thought to be reliable, scientific and accurate, perhaps they might want to decide which “fact” is science, and which “fact” is marketing, and whether they want to deal in fact or marketing.
Perhaps they want to consider that there might come a day when they suggest a fourth MMR, and the public rebels against anything they have to say.
Perhaps members of the American public who believe that CDC is dishonest, incompetent, or worse, deserve an evidence based explanation as to why a third MMR doesn’t mean two MMRs aren’t doing their job.