Screening of asymptomatic people could decrease COVID-19 infections

When the novel coronavirus (COVID-19) pandemic is slowing, low-cost, recurring screening of asymptomatic people, at an expense of approximately $3 or less per test every two weeks, could decrease COVID-19 infections and deaths and be cost-effective, according to new research led by researchers at Massachusetts General Hospital (MGH) and published in the journal Clinical Infectious Diseases. Additionally, when the pandemic is surging, screening can be cost-effective when done more often, even if tests costs are higher.

COVID-19 testing refers generally to testing of people with symptoms of the illness, while screening refers to testing of individuals who do not have symptoms of the infection. In the United States, restricted testing capacity early in the pandemic led states such as Massachusetts to test only severely symptomatic people and those with a known exposure to someone with COVID-19. However, making COVID-19 testing available to all people with symptoms suggestive of the illness, as well as expanding to screening programs for the entire population, including those without symptoms, could reduce hospitalizations and deaths, allowing for safe resumption of economic and social activity, the researchers said.

The study used a dynamic transmission model developed by members of the research team to analyze the outcomes anticipated from several different strategies for COVID-19 testing and screening for the entire population of Massachusetts, using laboratory-based polymerase chain reaction (PCR) tests. The PCR test uses a sample taken from the nose or mouth, usually a nasal swab or a saliva sample, which is then sent to a laboratory that tests for the virus causing COVID-19.

The analysis revealed that repeated screening of the entire population would lead to the most favorable clinical outcomes, preventing the greatest number of infections, hospitalizations, and, ultimately, deaths. This was true in a wide range of scenarios, ranging from decreasing to rapidly rising numbers of new cases per day. Such a screening strategy could also be cost-effective, depending on the cost of the test and the frequency of screening.

“While the outbreak is now under reasonably good control, questions remain about how to optimally deploy COVID testing, both in our current situation and in other settings and communities where new infections continue to rise," said Anne Neilan, MD, MPH, lead author of the study and investigator in the MGH Divisions of General Pediatrics and Infectious Diseases and the Medical Practice Evaluation Center, in a statement. "While some have argued testing must be highly sensitive to be of value, others suggest that sensitivity can be sacrificed if tests are rapid, low-cost, frequent, and widely available."

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