The whooping cough epidemic that spread across Washington state the last several months is waning, but health officials say people should remain vigilant about getting vaccinated.

More than 4,500 cases of whooping cough - or pertussis - were reported across the state this year, the highest number of cases in more than 70 years, according to the state Department of Health. Over the same period in 2011 just 642 cases were reported. Some areas are still dealing with high numbers of cases while others already have hit peak levels and are returning to more normal numbers.

Whatcom County was at the center of the epidemic with 327 confirmed or probable cases so far this year, though the statistics tend to lag so the number is expected to increase.

All of Whatcom County had about 50 cases in 2011, according to data from the County Health Department. That's fewer than the peak month of 2012, when 84 cases were logged in May.

Of the 2012 local cases, 29 were infants, who are most vulnerable and can die from pertussis.

Because of the danger to infants, and the possibility that the vaccine might not be as long-lasting as previously thought, an advisory committee to the Centers for Disease Control and Prevention has recommended that women get a vaccination with each pregnancy. Once born, the child will have some protection until he or she has had the proper immunizations on a regular vaccination schedule.

The CDC has done whooping cough case reviews in Whatcom County as it studies the effectiveness and longevity of the current vaccine, said Greg Stern, Whatcom County health officer. It's possible the CDC will modify its recommended vaccination schedule.

Until then, the CDC recommends that children begin a five-dose series that starts at age 2 months and concludes before age 7, followed by a booster at age 10 or 11. Adults should get a one-time booster of the vaccine known as Tdap.

The epidemic and awareness of it led to twice as many adults getting their Tdap booster in 2012 than the year before, according to the state Department of Health.

Still officials are urging those who will be around babies during the holiday season to make sure they're up-to-date on their own whooping cough vaccines.

For more information on whooping cough, go to doh.wa.gov.

Reach DEBBIE TOWNSEND at debbie.townsend@bellinghamherald.com or call 715-2280.