Vashon’s low vaccination rates among school children have persisted this year, and school nurse Sarah Day hopes to see an increase in the numbers of students vaccinated against two of the most contagious and potentially serious diseases: pertussis and measles.

Statistics about who is vaccinated and who is not have recently been tabulated, and according to Day, who was new to the district this fall, the results are worrisome. District wide, 33 percent of students have not been fully vaccinated against pertussis, also known as whooping cough, a respiratory illness potentially deadly for infants. Twenty-two percent have not been fully vaccinated against measles, which had been eradicated in North America in 2000, but has since made a resurgence, largely because of parents declining to vaccinate their children.

Day stressed that she understands vaccination has long been a contentious issue on the Island and beyond and that she believes parents choose to vaccinate or not based on what they believe will be best for their children. She also stressed that science points to the safety of vaccines, and she feels increasing the vaccination rate among students for these two illnesses will hold benefits for the individual students and the community as a whole.

“I would love for folks who have an exemption for measles or pertussis to look at current data and reexamine that decision,” Day said.

The measles vaccine, in particular, raised concern for parents when British surgeon and researcher Adam Wakefield published a paper in the respected medical journal The Lancet in 1998, raising concerns about the potential link between autism and the measles, mumps and rubella vaccine (MMR). While Wakefield still has some followers, his work has been discredited, and considerable research since indicates there is no link between the MMR and autism. Still those concerns and other vaccine-safety concerns linger, and concern about measles is on the rise in many quarters, including Vashon.

“Measles is coming,” Day said recently.

Fear about measles  is so high, Day said, because it is among the most contagious of diseases, and it has a high rate of serious complications, including pneumonia and encephalitis, an inflammation of the brain that can cause permanent disability.

In Washington in 2011, there were four cases of measles, according to Michele Roberts of the Washington State Department of Health. As the occurrence of measles has begun to increase after its eradication in this country 11 years ago, Washington has seen anywhere from no cases each year to a handful of cases. Other states have not been quite so lucky this year, she noted.

“There is a significantly higher number of cases than in recent years,” she said.

According to the CDC, between Jan. 1 and May 20 of this year, there were 118 cases of measles in the United States, the highest number since 1996. Eighty-nine percent of the people who got the disease were unvaccinated. Forty percent were hospitalized, with the highest hospitalization rates in infants and children under 5.

Other countries have had much larger outbreaks than the United States, including Canada and France, which, according the World Health Organization (WHO), had more than 14,000 cases in the first seven months of this year, nearly triple the number from 2010. A vaccination campaign in that country began this fall in an effort to curtail the disease, which is extremely costly to contain.

Both Day and Roberts noted that as people travel and then return to their communities, those who have not been vaccinated become vulnerable.

“All it would take is one unprotected person who … would bring it back here,” Day said. “We would have a person with a highly contagious disease with a high rate of complications in a population that could not provide good protection for those people who are the most vulnerable.”

Day also noted that the measles vaccine is very effective: Given appropriately, it will protect more than 99 percent of those who receive it. According to WHO, if at least 95 percent of a population is vaccinated against measles, the disease can be eliminated completely.

For pertussis — which Day called “bad news for babies and younger kids” — the picture is a bit different. Neither the illness itself nor the vaccine provides lifelong immunity to the disease, and the vaccine is not as effective as the measles vaccine. In fact, it is only 59 to 89 percent effective in preventing pertussis, Day said, making it even more important that high numbers of people are vaccinated against the illness.

“We need a higher level of herd immunity to keep this one at bay,” she said.

Keeping whooping cough at bay is particularly important because of the risk it carries for infants. The recommendation is that students receive the DTaP series as young children and the Tdap booster before they enter middle school. Day noted that even if the vaccine does not provide complete protection, it is valuable because it attenuates the illness in those who do contract it.

According to data from the state Department of Health, there were 728 cases of pertussis in Washington from Jan. 1 to Dec. 17. This compares with 529 cases in the same time period last year. Eighty-six infants under 1 had the illness and 29 were hospitalized, including 23 who were under 3 months. Two infants died. Looking closer to home, King County has had 81 confirmed cases this year, according to James Apa, the communications manager for Public Health – Seattle & King County. This is within the normal range, he said, but both Pierce and Snohomish counties are experiencing higher than normal rates of the disease.

At the state level, Roberts said public health officials are always concerned about pertussis because of the disease’s severity in infants and the fact that some level of pertussis is always circulating. She noted two infants died in Washington in 2010 as well.

At the school district, Day said that by law she is required to notify parents if they are missing any of the required vaccines, but she noted she will make an extra effort for these two illnesses, which she believes carry the highest risk for Vashon.

“We have vulnerable friends and neighbors,” she said. “We know these people. We’re an Island.”

Soon she will email letters to parents with information she feels is important and will follow up if she does not hear back.

“I would like to see if we could boost our numbers of people who are protected,” she said.