Despite cases of the measles now showing up in Santa Clara County, some Palo Alto schools still have up to 12 percent of elementary school students who are not properly immunized, according to data from the California Department of Public Health.
Five Palo Alto Unified School District elementary schools range from 88 to 93 percent immunized students; two private Palo Alto elementary schools fall below 94 percent. For a population to be adequately protected from measles, researchers generally think up to 94 percent of people must be immune either by prior infection or by vaccination. Some studies, however, assert that rate could be as low as 83 percent.
Measles is a highly contagious respiratory disease that is caused by a virus. California has recently seen 79 confirmed measles cases as of Wednesday, Jan. 28. Two cases each were in Santa Clara and San Mateo counties. An outbreak at Disneyland accounted for 52 cases, according to the department of public health.
Palo Alto schools in general have a high rate of students whose measles vaccinations are up to date. Duveneck Elementary's students are all vaccinated, and 99 percent of Nixon's are.
But 12 percent of Addison students are not adequately vaccinated; 9 percent of Walter Hays, Ohlone and Juana Briones students are lacking immunization, as are 7 percent at El Carmelo.
The private Challenger School has a 13 percent unvaccinated rate, and St. Elizabeth Seton's is 10 percent, according to the state data. (UPDATE: St. Elizabeth Seton disputes the figures and says 100 percent of students are immunized.)
But school district spokesperson Tabitha Kappeler-Hurley questioned the state's figures. Children whose families traveled during the summer might not have gotten a needed vaccine just before school, she said, but they were immunized later and that fact was not capture in the public-health department's numbers.
The district's figures for measles under-immunization show Addison at 5.1 percent, Juana Briones at 3.5 percent, Ohlone 7 percent and Walter Hays at 3.2 percent.
Challenger School officials did not return requests for comment on why the numbers of unvaccinated students are high.
In East Palo Alto, all public elementary schools are within the 96- to 100-percent immunization range, according to the state data.
A Kaiser Permanente study published Jan. 18 in the journal Pediatrics found that race, ethnicity and neighborhood income were not dominant factors where clusters of low immunization were found. But there were lower vaccination rates in families with more graduate degrees. The study did not analyze the reasons.
Dr. Ross DeHovitz, an immunization expert at Palo Alto Medical Foundation, said that resistance to immunizing has come in waves, with the most recent wave occurring after the 1998 Wakefield study linked autism to the measles vaccine. That study has since been debunked, and the medical journal The Lancet retracted the research. But hesitancy is still pervasive, he said.
Some parents do receive exemptions based on personal, faith or for medical reasons, Kappeler-Hurley noted. But California law now requires a signature from a health care practitioner to obtain the exemption.
The Kaiser study did find a correlation between under-vaccination and increased disease incidence.
"Measles cases were relatively rare until 2014. It's taken off across the country, aided by previous outbreaks in Ohio and New York and now at Disney," Dr. Charles Weiss, a Palo Alto Medical Foundation public-health expert, said.
Parents who have not had their children vaccinated should be very concerned, he added.
"If you put one person with active measles into a population without measles who are not immune, it will spread to 12 to 18 people," Weiss said. By comparison, someone with influenza would infect one or two people, he said.
Measles begins with a fever that lasts a couple of days, followed by a cough, runny nose, conjunctivitis (pink eye) and a rash. The rash typically appears first on the face, along the hairline and behind the ears and then affects the rest of the body, according to the public-health department. Infected people are usually contagious from four days before the rash appears to four days afterward. Weiss said complications can include pneumonia, severe diarrhea, encephalitis and death.
Palo Alto Medical Foundation does not normally see any cases of measles. So far, systemwide, PAMF has confirmed two cases, one each in 2014 and 2015, Weiss said.
Measles vaccine is a live virus that has been weakened through manufacturing. Two doses are necessary because only 90 percent of people respond to the first vaccine by creating adequate antibodies. The second brings the response rate to 99 percent, DeHovitz said.
The vaccine can sometimes cause a very mild infection, he said. The vaccinations provide a lifetime of protection, he added.
Adults born before 1957 are generally considered immune to measles because it was so pervasive at that time, so no further action is necessary.
To count as up to date for school records, a child must have received both doses on or after the first birthday, according to the state health department.
If anyone suspects they might have measles, they should not run to the doctor's office, Weiss said. The disease is so contagious that it could infect people in the waiting room.
"Call if you or a family member develops a fever and rash that is associated with a runny nose, cough and red eyes. Stay put at home. Don't come in without calling. You'll be met at a side door and given a mask by a staff person," he said. Anyone who has traveled within 21 days and has symptoms should also tell their doctor.