The San Mateo County civil grand jury suggests that school and public health officials be on guard for the kind of measles outbreak seen elsewhere in the country. The grand jury issued its report on July 17. There have been 1,123 confirmed cases of measles in the United States from Jan. 1 to July 11, 2019, and the outbreak spans 28 states. This is the greatest number of measles cases reported in the nation since 1992.
Measles was declared eliminated in the U.S. in 2000, when there were only 86 cases reported and no continuous transmission of the disease for more than 12 months. Since then, the highest annual number reported was 667, in 2014.
The outbreak is linked to travelers who brought measles back from countries like Israel, Ukraine and the Philippines, where large measles outbreaks are occurring, officials say.
In 2019, four isolated cases of measles have been reported in San Mateo County, according to the grand jury’s report.
The San Mateo County Health Communicable Dis-ease Control Program has ensured that, once identified, infected individuals are isolated and other exposed individuals are tracked down to limit the spread of measles. As a result, none of the cases of measles reported in 2019 were able to spread further, the grand jury notes.
The San Mateo grand jury was interested in the measles immunization rates of children and adults and the actions taken by San Mateo County agencies to minimize the risk of an outbreak.
California law requires vaccinations against measles, among other diseases, to enter preschool, kindergarten and seventh-grade classes in public and private institutions. Health officials consider vaccination rates of at least 93 percent to be acceptable immunity. The average vaccination rates for San Mateo County youth have exceeded this percentage in recent years, but vaccination rates fell below that threshold in some county schools in the 2017-2018 school year.
The state allows some medical exemptions. State Sen. Richard Pan has proposed Senate Bill 276, which tightens medical exemptions to a list outlined by the Centers for Disease Control and Prevention. The law would require California’s Department of Public Health to create a uniform document for doctors to administer an exemption, and exemptions would be monitored by the state health department.
While the vaccination rate of children in San Mateo County is well monitored and documented, much less is known about the vaccination rates of the adult population. Health officials believe that people born before 1957 developed an immunity due to exposure to the disease, and while vaccinations have been available across the U.S. since 1963, the rates of vaccination have fluctuated.
Experts say California’s relatively strict vaccination law is why it has been largely spared during the current measles outbreak, which is much more severe in New York, for example. The outbreak in New York, which allows a number of exemptions, began when an unvaccinated child became infected while visiting Israel. That state subsequently declared a public health emergency. Locally, the major transportation systems, including an international airport in San Mateo County, add to the risk of transmission, experts say.