What it didn’t do: stop COVID-19.
“Despite intense efforts, the traveler screening system has not effectively prevented the introduction of COVID-19 in California,” the United States Centers for Disease Control and Prevention concluded in a new report released Monday.
Only three of 11,547 international travelers reported to local health authorities for follow-up after landing at California airports from February 3 to March 17 were on the state’s list of more than 26,000 cases of coronavirus in mid -April.
Two were from Iran and a third was from China.
The report reveals the challenge of trying to hermetically seal a nation.
“Tracking travelers has been a lot of work and has been limited by incomplete information, the volume of travelers and the potential for asymptomatic transmission,” the report said.
The return traveler surveillance team, made up of the California Department of Public Health, required 1,694 “person hours” – the equivalent of six people working full time for seven weeks.
President Donald Trump said he had slowed the spread of the coronavirus in the United States by acting decisively to ban travelers from China and Iran on January 31. There have been delays in passenger screening in Italy and South Korea, despite the increase in cases in these countries.
During hearings last week, a subcommittee of the US House of Representatives, led by Democrats, said that information from several US agencies had revealed that the testing program had done little to help to stop the spread of the virus at American airports.
In recent weeks, many countries around the world, including the United States, have imposed travel restrictions to help curb the spread of the coronavirus. Airport closures, the suspension of all inbound and outbound flights, and nationwide closures are just a few of the measures that countries are taking to try to contain the pandemic.
Screening for COVID-19 by travelers presents a major challenge: it does not detect asymptomatic infections. Airport sanitation is most effective when infected travelers can be easily identified, according to the CDC.
For example, surveillance of the Ebola virus in Africa during the 2014-2015 period was effective because the disease has obvious clinical symptoms. And Ebola is not contagious until symptoms appear.
Screening is also easier if there are a relatively small number of travelers who need to be followed. During the Ebola outbreak, only 21 travelers a week from three African countries affected by the disease were followed, on average, in California.
This compares to the 1,431 travelers who had to be monitored weekly for signs of COVID-19.
In addition, the effectiveness of the California program was limited by incomplete information on travelers received by federal authorities and reported to states, as well as by the number of travelers needing follow-up, the report said.
About 13% of the records had errors and needed to be corrected. These ranged from incorrect U.S.-based phone numbers to insufficient location data, misspelled names, or wrong dates of birth. Some records were duplicates. Flight manifests or other independent recordings to verify that traveler information was not available.
This has delayed efforts to reach travelers – and some travelers have been completely lost to the authorities.
To be successful, these programs need more efficient methods of collecting and reporting passenger data, so local health authorities can quickly reach travelers at risk, according to the CDC. This would facilitate rapid testing, case identification and “contact tracing” investigations.
The effectiveness of airport control may also depend on the phase of a pandemic.
This is most effective from the start, when containment is possible – but could also be useful in the future, since community transmission is decreasing and our borders are once again in need of protection, according to the CDC.
If we are faced with new waves of disease, according to the report, “reconfigured and targeted traveler surveillance, with accurate demographic and contact information on travelers and increased staff, could be helpful in maintaining a low incidence of disease. “