Coronavirus tracking in California of nearly 12,000 travelers has been ineffective, says CDC report


The California Department of Public Health’s efforts to track thousands of travelers to the state this year not only prevented the coronavirus from entering, but used limited time and staff at a time when the disease was starting to spread in communities.

State health workers spent nearly 1,700 hours over six weeks – February 5 to March 17 – collecting and processing information about US citizens and permanent residents arriving from China and Iran in the California airports. However, they could only identify three positive cases out of 11,574 travelers, according to a report released Monday by the state department of public health and the United States Centers for Disease Control and Prevention.

“Despite intensive efforts, the traveler screening system has not effectively prevented the introduction of COVID-19 in California,” said the report, noting that “health services must weigh the resources needed for surveillance versus to those necessary for the implementation of mitigation activities during the COVID-19 pandemic. “

The CDC coordinated with local and state health departments in California to start the follow-up program before officials believed the disease was spreading in the community. We now know that the program started a day before the country’s first death from an unknown source in Santa Clara County, probably while the virus was already circulating in the Bay Area.

At the start of the epidemic, county public health services were able to stay on the lookout for small groups of cases through investigation and contact tracing. But most counties had very limited contact tracing personnel and, as the virus began to spread widely in early March, they were forced to reduce this intense surveillance. They also abandoned surveillance of travelers, as most people were infected with an exposure in their own community.

Instead, public health services have shifted staff and other limited resources to cheaper but more draconian efforts to prevent an explosive growth of the epidemic and protect hospitals from overflows. In fact, the state ended its travel surveillance program on March 17 – the same day, six counties in the Bay Area began sheltering there in a dramatic move to contain the virus.

As part of this program, customs and border protection officials interviewed thousands of people returning to the United States. Passengers were asked about their travel history and symptoms. If they showed symptoms, they were directed to a separate post managed by the CDC for medical assessment and mandatory quarantine. If they did not, they were encouraged to isolate themselves at home for 14 days and monitor their health. The officers then shared the names, dates of birth, addresses and telephone numbers of the travelers with the CDC, which forwarded them to the California Public Health Department.

State officials – doctors, epidemiologists and other personnel – spent nearly 1,700 hours researching information for nearly 12,000 travelers, or about 1,430 per week. A third of the hours were overtime, the report said.

The labor-intensive process has been slowed down by bad information, the state said. More than 1,500 records – 13% – contained at least one error. Most of these records had an incorrect telephone number. Some were duplicates and others did not have sufficient location data or the traveler lived outside of California. Staff suspected that there were even more errors in names and dates of birth.

The state health department had to correct the errors before sending information to 51 counties in California. The state then asked local authorities, if resources allowed, to contact and supervise travelers for two weeks.

Local public health officials then used this information to contact travelers over a two-week period and track their symptoms. This resulted in two cases of COVID-19 – two travelers from Iran, one on March 10 and another on March 14. A third person who traveled from China tested positive on March 30, six weeks after returning to the United States – but well after local health services reportedly followed suit.

The report does not say how much the state spent on the massive effort, which was also hampered by the volume of travelers.


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