63% Americans wait over 1 or 2 days for Covid-19 test results, hampering efforts to control spread: Study
Timely test results are necessary to slow down Covid-19 but there are critical delays across the US, according to researchers who found that the system is too slow for contact tracing and isolation to be effective. An estimated 63% of US residents are waiting longer than one to two days to get their coronavirus test results — delays that undermine contact tracing that could identify individuals who are contagious but show no symptoms, reveals a new survey by a team from Northeastern University, Harvard University, Northwestern University, and Rutgers universities. The testing challenges are national in scope, with most states reporting a median waiting time of three days or more.
Overall, the average wait was four days, but in some cases it was as long as 10 days or more for about 10% of respondents in the study. According to the authors, the findings are significant in that health authorities consider rapid turnarounds essential to containing the Covid-19 pandemic, which has, so far, resulted in the deaths of more than 161,320 in the US and has infected over 4,940,930. Even more worrisome is that wait times do not seem to be decreasing across the country, they add.
The research team explains that a delay of even a day is critical given that the peak of contagiousness lasts about one week. In that time, many could be infected with the new coronavirus if they come in contact with someone who may seem healthy, making a positive test virtually useless. "Ideally, test results would be available the same day. Our findings indicate that the US is not currently performing testing with nearly enough speed. Most (63%) people are not getting results within the 1-2 days that would be optimal to aid contact tracing. Given the timing of how quickly and how long someone is infectious, speed in producing reliable enough results is of the essence for Covid-19,” write the authors in their report.
The online survey of 19,058 people across all 50 states and the District of Columbia was conducted between July 10 and July 26. It asked residents if they had been tested for Covid-19 and how long they waited to get the results back. About 18% of all respondents had been tested for Covid-19 at least once.
The analysis reveals that 37% of those who had been tested by nasal swab received results within two days, with 31% of tests taking more than four days and 10% for 10 days or more. Further, there are few signs that turnaround times are decreasing. For individuals who responded that their last test had been in April, they had waited on average 4.2 days to get results, for those who were tested in July, it was 4.1 days. "We find that the mean waiting time nationally was 4.1 days, and median waiting time 3 days. Only 37% of people received test results within 2 days, and 21% waited more than 5 days," the findings state.
The waiting time is strikingly similar across states — with six states (Hawaii, Iowa, Kentucky, New Jersey, Ohio and Washington) having a median waiting time of two days, 12 states (Arizona, Arkansas, California, DC, Delaware, Florida, Montana, Nevada, Oklahoma, South Carolina, Tennessee and Texas) more than three days, and for 33 states with a median time of exactly three days. The relative consistency of long waiting times throughout the country highlights that it represents a national problem, not a local one, the researchers emphasize.
The team also found that the waiting time for results is not evenly distributed across the population. While the average wait times for White respondents were 3.9 days, it was 5 days for Black people, and 4.6 days for Hispanic respondents. The longer wait times for African-Americans and Hispanic Americans mean that containment strategies will be less effective in those populations, says the team.
The reasons for delays in getting test results out faster invariably point to a bottleneck in national testing labs, according to David Lazer, a distinguished professor of political science and computer and information sciences at Northeastern, and one of the researchers who conducted the study. “They are simply overwhelmed,” Lazer writes in the study.
Why are the findings important?
Testing is a cornerstone of containing the spread of Covid-19. In particular, public health experts have indicated that a testing regime for controlling the spread of the disease should involve testing higher risk asymptomatic individuals, isolating positive cases, and testing the contacts of positive cases and repeating this cycle. According to the authors, this type of control strategy, effectively implemented, could help limit the spread of the disease while reducing reliance on far more costly interventions, such as stay at home orders and shutting down schools.
This testing and isolation strategy works because it reduces exposure of people to individuals who are contagious but have no symptoms, explain researchers. "This asymptomatic transmission is the key driver of the spread of Covid-19 since people who are infected but not showing symptoms are more likely to go about their daily routines without adopting behaviors to prevent transmission. As a point of comparison, a previous coronavirus first reported in Asia in 2003 (Severe Acute Respiratory Syndrome, or SARS) did not spread nearly as widely because infected individuals were generally infectious only after they started demonstrating characteristic symptoms,” the report states.
The authors argue that if individuals with Covid-19 “simply manifested with a purple nose” before they were contagious, the disease would be easier to contain and would quickly disappear. “Testing is the functional equivalent of that purple nose. In a world where everyone could take a perfectly accurate test every day that would produce results in a few minutes, and self-isolate after a positive result, new infections would drop to near zero within a few weeks. While we are some distance from that ideal scenario, the cycle of testing and contact tracing, if rapid enough, gets us closer to that possibility,” they explain.