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Q&A on whooping cough: Have vaccinated people still gotten sick?

September 17, 2010 | 11:15 am

WhoopingcoughA number of readers have contacted The Times wanting to know more about the whooping cough outbreak and who has been affected by the severe bacterial disease. State officials said this week that the epidemic is now the worst in the state for pertussis in 55 years, killing nine people, all infants younger than 3 months of age.

As The Times continues to cover the outbreak, readers are encouraged to send their questions to ron.lin@latimes.com.

Question: How many of the 4,000 or so people in California infected with whooping cough had been immunized against the disease?

Answer: According to the state, at least 544 adults and children, ages 15 months and older, had received at least four shots required for whooping cough immunization and still got sick.

But health officials caution that it is important to keep in mind that while other vaccines confer lifelong immunity, an inoculation to whooping cough, also known as pertussis, may only protect the recipient for as few as five years.

That’s why after babies get their first set of Dtap pertussis shots at ages 2 months, 4 months, 6 months and 12 months, they then need a booster between the ages of 4 and 6.

Adolescents between the ages of 11 and 12 should get another pertussis booster shot, a different type known as Tdap, which was just introduced in 2005. Adults can also get the Tdap booster shot.

Health officials say getting a pertussis shot is an effective way to prevent getting sick and spreading the disease. But sometimes, the vaccine fails.

In the case of the vaccinated people who still contracted whooping cough, 58 had received immunizations in the last year. Data on whether those immunized earlier had received booster shots was not immediately available. State officials said further study is needed to understand the role of vaccine failure and waning vaccine immunity in the cases.

-- Rong-Gong Lin II

Previous Q&As:

How many of the eight infants who died were immunized for whooping cough?

Are illegal immigrants fueling the outbreak? State officials say no


California weekly update for Sept. 14