A Harvard epidemiologist has warned that traveller screening in the United States may not detect most symptomatic cases of COVID-19. And he said that the 233 cases uncovered so far may be tip of the iceberg.
Marc Lipsitch, a professor of epidemiology at the Harvard T.H. Chan School of Public Health. compared the epidemic to an iceberg, with the most severe cases — those who have died or sought medical care or who have been tested — at the iceberg’s tip. He urged scientists to better understand the unseen, underwater portion.
The modelling result using a robust screening programme in Singapore showed that most countries’ screening procedures at borders miss two-thirds of travellers exhibiting COVID-19 symptoms, Lipsitch said,
The model compared the number of people likely exhibiting COVID-19 symptoms with the number caught by traveller-screening programs.
It may explain the recent appearance of a cluster of cases in Washington State, said Lipsitch, adding that travellers sick with COVID-19 likely arrived in the United States four to six weeks earlier and simply were missed in screening, thus leading to the Seattle area outbreak.
“I think you could have certainly hundreds, if not more, cases around the United States by this point,” said Lipsitch.
The U.S. Centers of Disease Control and Prevention reported 148 cases of COVID-19 as of Wednesday, including 49 which are still not clear how they get affected.
Uncertainty over how many U.S. cases there are raises the urgency of conducting more virus tests, but Lipsitch said the pace of testing is still low, and it will “take weeks until we have anything like adequate testing capacity.”
“Right now, it is a challenge if you are a doctor wanting to get somebody tested,” said U.S. Health and Human Services Secretary Alex Azar on Thursday.
“That experience will get better over the next week, week and a half, two weeks.”