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.
The number of travelers to track in each county varied from one to 4,852, according to the report, and tracking capacity “varied considerably depending on the resources and volume of travelers.” The San Francisco public health department followed hundreds of travelers, said spokeswoman Veronica Vien.
“We have been faced with challenges, including but not limited to incomplete information on passengers and travelers and asymptomatic carriers of the disease,” she said.
Such monitoring – which usually includes airport control, quarantine and tracking of travelers – has been an effective method of stopping diseases like the Ebola virus, according to the report, written by state employees. But to work well, the process requires precise contact details for travelers.
The report also says that airport surveillance may not always work to detect COVID-19, as symptoms may or may not appear a month after infection. The report recommended more efficient methods of collecting and transmitting data, including obtaining passenger information from airlines and using text messaging to reach all travelers at risk more quickly.
More rural health services likely lacked the resources to quickly track infections when the disease was already raging, said George Lemp, former director of the California HIV / AIDS Research Program in the office of the President of the University of California, who oversaw contact tracing programs during the AIDS epidemic.
“If the numbers are in the thousands, they can’t deal with them quickly,” he said. “They couldn’t do it fast enough to prevent the spread of a virus like this. “
“Contact tracing is best reserved where the incidence and the rapid speed of the virus have diminished,” he added.
Some Bay Area health services are now hiring and training thousands of people to conduct coronavirus contact tracing as part of efforts to reopen society safely. The recent state report warns of work intensity, says Lemp.
“This highlights the difficulty we face,” he said.
Column editor Erin Allday contributed to this report.
Mallory Moench is a writer for the San Francisco Chronicle. Email: [email protected] Twitter: @mallorymoench