The use of at-home coronavirus tests jumped during the Omicron wave, but disparities remain, a survey suggests.

The use of at-home coronavirus tests surged during the winter Omicron wave in the United States, with white, high-income and highly educated people most likely to report using the tests, an online survey of U.S. adults suggests.

Between Dec. 19 and March 12, 20.1 percent of survey respondents who said they had symptoms consistent with Covid-19 reported using an at-home test, up from 5.7 percent between late August and early December, when Delta was the predominant coronavirus variant in the United States.

The use of at-home tests increased over the course of the fall and early winter, the survey found, peaking in January, when 11 percent of respondents reported having used an at-home test in the previous 30 days.

Nearly 40 percent of those who used at-home tests said they did so because they had been exposed to someone with Covid-19; 28.9 percent said they tested themselves because they were experiencing Covid-like symptoms. Testing for work, school and travel was less common, the researchers found. Those who were vaccinated and boosted were more than twice as likely to report using at-home tests as those who were unvaccinated.

The study was led by researchers at Boston Children’s Hospital and the Centers for Disease Control and Prevention. It is based on an online survey of more than 400,000 U.S. adults conducted between Aug. 23 and March 12. Participants were asked whether they had symptoms consistent with Covid, whether they had been tested for the virus within the previous 30 days and, if so, what kind of test they had used.

The results are consistent with reports of rising demand for at-home tests as the highly contagious Omicron variant spread and Americans relied on self-testing as a precaution before and after holiday travel and gatherings. The availability of at-home tests has also increased in recent months as manufacturers have ramped up production and the Biden administration began mailing free tests to American households in January.

Among respondents with household incomes of more than $150,000 a year, 9.5 percent reported using at-home tests, compared with 4.7 percent of those with household incomes between $50,000 and $74,999 and 3.1 percent of those with household incomes of less than $15,000. Among those with postgraduate degrees, 8.4 percent reported at-home testing, compared with 3.5 percent of those with a high school degree or less. White survey respondents were twice as likely as Black respondents to report using the tests. Improving education about testing and expanding access to free tests could help reduce the disparities, the researchers said.

The findings come as the demand for testing falls and some states begin to shutter their public testing sites. It is not clear how many of those who tested positive on at-home tests reported their results to health authorities or confirmed their infections with follow-up P.C.R. tests. But some experts have expressed concerns that an increasing reliance on at-home tests could make it more difficult for officials to keep tabs on the virus.

The self-reported use of at-home tests began declining last month, as the number of U.S. cases declined, according to the survey.