(CNN) -- Wearing personal protective equipment (PPE) when caring for patients with Covid-19 isn't enough to completely eliminate the threat from the virus for frontline workers, according to a new study from King's College London.
Health care workers with adequate gloves, gowns and face masks still had 3.4 times the risk of contracting the coronavirus compared to the general population, the study found, and minority health care workers had an even greater risk of testing positive.
African American, Latino and other minority care providers were five times more likely to contract Covid-19 than their White counterparts, the study found.
"A little over 20 percent of front-line health-care workers reported at least one symptom associated with SARS-CoV-2 infection compared with 14.4 percent of the general population; fatigue, loss of smell or taste, and hoarse voice were especially frequent," the researchers wrote.
The researchers used the COVID Symptom Tracker app to study the data of more than 2 million people, including almost 100,000 frontline health care workers in the United States and the United Kingdom between March 24 and April 23.
They found more than 2,700 cases of Covid-19 per 100,000 healthcare workers compared with just over 240 cases per 100,000 among the general population.
"After accounting for differences in testing for healthcare workers compared with the general community, the researchers estimate frontline workers are around 3.4 times more likely to test positive for COVID-19," the researchers wrote.
"The data is clear in revealing that there is still an elevated risk of SARS-Co-V-2 infection despite availability of PPE," said King's College London professor and senior study author Sebastien Ourselin.
Not only did researchers find that minority health care workers had an increased risk of Covid-19 infection, they also found that they were more likely to report a lack of adequate PPE and said they were forced to frequently reuse equipment, Ouselin said.
Previous studies have found that 10-20% of coronavirus infections occur among frontline workers.
"Our study provides a more precise assessment of the magnitude of increased infection risk among healthcare workers compared to the general community," said Dr. Andrew Chang, a senior study author and director of cancer epidemiology at Massachusetts General Hospital.
At the time the study was conducted, health care providers in the US and the UK were experiencing severe shortages in gloves, gowns and face masks. The authors said the results of a similar study now might be different.
"Many countries, including the US, continue to face vexing shortages of PPE," Chang said. "Our results underscore the importance of providing adequate access to PPE and also suggest that systemic racism associated with inequalities to access to PPE likely contribute to the disproportionate risk of infection among minority frontline healthcare workers."
The research suggests health-care systems should ensure adequate availability of PPE and develop additional strategies to protect health-care workers from COVID-19, particularly those from Black, Asian and minority ethnic backgrounds
The study was published Friday in the journal Lancet Public Health.