Getting vaccinated continues to be the most effective way to prevent infection, local health experts say, as the number of confirmed measles cases grows nationwide.
Measles: A highly infectious virus
“Measles is the most infectious disease that we know of,” said Dr. Karen Smith, Sonoma County’s interim health officer. In an unvaccinated population, on average someone infected with measles will go on to infect 10 to 15 other people, Smith said. About 90% of unvaccinated people who are exposed to the virus will become infected, she added. “There are very few viruses or bacteria or any other pathogen that passes from person to person that is that efficient,” Smith said. Measles is far more infectious than COVID-19 now is and it doesn’t take much of the virus to cause an infection, Smith said. When someone with measles coughs or sneezes, tiny viral particles dry out in the air and can remain airborne for some time, compared to most other pathogens. With COVID-19, influenza and respiratory syncytial virus, or RSV, a large amount of viral particles are required for infection. Measles requires only “five viral particles is all it takes,” Smith said. As
President Donald Trump’s top health official spreads fringe theories about current measles outbreaks, Sonoma and Napa county health officials are encouraging local residents to continue inoculating their children with what is widely considered one of the best vaccines ever created. Earlier this month, Robert F. Kennedy Jr., the nation’s health and human services secretary, gave a lukewarm endorsement of the MMR vaccine, which protects against measles, mumps and rubella. But he’s since trotted out strategies against current outbreaks that include questionable treatments such as cod liver oil and the use of steroids and antibiotics. Getting vaccinated continues to be the most effective way to protect children, said Dr. Karen Smith, interim health officer for Sonoma County
, where no confirmed measles cases have yet been documented. Likewise, no cases have been reported in Napa County. State officials have yet to respond with the latest information on Lake and Mendocino counties. California so far has confirmed 5 measles cases this year. The larger outbreak in Texas, which started in late January in a
small Mennonite community , is clear evidence of what can happen to those who are not vaccinated or have no natural immunity from previous infection, Smith said. “Measles is the most infectious disease that we know of,” said Smith. In an unvaccinated population, on average someone infected with measles will go on to infect 10 to 15 other people, Smith said. About 90% of unvaccinated people who are exposed to the virus will become infected, she added. “There are very few viruses or bacteria or any other pathogen that passes from person to person that is that efficient,” Smith said. It is precisely that degree of infectiousness that requires such a high level of “herd immunity,” about 95% in a specific community, to keep the virus from spreading. During the 2023-2024 school year, the share of Sonoma County kindergartners who had all of their required Immunizations was 93.5%. Child immunization rates are higher in Napa County, where 98.99% of kids entering kindergarten had their MMR inoculations in the 2023-2024 school year. Napa County’s vaccination rates for all required school vaccines, including, polio, hepatitis B, DTaP (diphtheria, tetanus and pertussis), varicella (chickenpox) and MMR, ranged between 98.65 and 99.10% that same school year, said Dr. Christine Wu, the county’s health officer. “We have one of the highest vaccination rates for MMR in the state,” Wu said. She credited the work of a county public health nurse who closely monitors each school and tries to get kids caught up on their immunizations. As of March 6,
the latest federal report , 222 measles cases have been documented across 12 states including California, according to the Centers for Disease Control and Prevention. The CDC updates confirmed measles cases every Friday. The New York Times in its
latest reporting said the total as of Wednesday morning was 250. The latest cases include an infected Los Angeles County resident who passed through the
Los Angeles International Airport on March 5 — several weeks after the
first reported measles-related exposure in the airport this year . For the whole of last year, 285 cases were reported nationwide. In 2023, there were 58. For contrast, in 1990, nearly 28,000 confirmed measles cases were reported in the nation. The virus was declared eliminated in the United States by 2000, a year after 1,274 cases were reported. The last confirmed cases of measles circulating in Sonoma County was in 1993, according to local health officials. The last confirmed case in Sonoma County, in 2011, was that of a traveler from Europe. There were two suspected cases in 2005, among local residents with measles symptoms but there was no conclusive testing. There have been two measles deaths reported in the United States, one tied to the outbreak in Texas and one in New Mexico that is currently under investigation. The Texas death involved a school-aged child who was not vaccinated and tested positive for measles. The case in New Mexico involved a resident of Lea County who was unvaccinated and tested positive for measles, according to New Mexico health officials. The official cause of death is still under investigation but state lab testing has confirmed the presence of the measles virus. Smith warned that aside from being highly infectious, measles is a highly problematic disease that can lead to other dangerous illnesses, including pneumonia. Before the vaccine was created, measles used to be “the number one killer of children in the developing world” and even in more developed nations, she said.
