An analysis of the medical histories of people who were tested for the new coronavirus by physicians shows that the infection exacerbates existing socioeconomic disparities.
According to a UK study, black people are four times as likely to test positive for SARS-CoV-2, the virus that causes COVID-19 compared to white people.
The research also found that people living in the most deprived areas were more than three times as likely as people living in the least deprived areas to test positive in comparison.
The study, now published in The Lancet Infectious Diseases, is one of only a few studies that investigate primary care settings for SARS-CoV-2 infection. Most research was done in hospitals and involved patients with severe illnesses.
The data would help to warn the UK about relaxing shutdown policies and recommendations on public health. And in the months ahead.
“While strong patterns have emerged from the hospital data for those with serious symptoms, the risk of infection remains a grey area in the general population,” says first author Professor Simon de Lusignan of the University of Oxford, who is also the head of the Royal College of Practitioners Research and Surveillance Centre (RSC).
“It is important to know the groups in the broader population are at greatest risk of infection, so we can better understand the transmission of SARS-CoV-2 and how to avoid new cases,” he continues.
The research examined anonymised electronic patient reports from 500 GP practice reports that upload data to the RSC automatically. The activities are generally reflective of the population at large.
A total of 587 people were identified by the researchers who tested positive for the virus and 3,215 who tested negative between January 28 and April 4 , 2020.
The patients underwent monitoring after developing influenza symptoms or other respiratory infections.
The percentage of black people who tested positively was 62.1% (36 out of 58 people) compared to 15.5% of white people (388 out of 2,497 people).
This finding was significant after adjustment to existing conditions such as high blood pressure and diabetes, which are more prevalent among black people and may also increase the risk of infection with SARS-CoV-2.
However, there is still the possibility that black people might be more likely to test positive because of other factors, such as where they work.
The authors write in their paper: “Other socioeconomic variables that we did not assess, such as high-risk jobs, schooling, income, and social barriers to health care, may have contributed to this association and should be investigated as a matter of national security.”
Contrary to a review of people who died with COVID-19 in the UK, the new study found that people in Asia were no more likely to test positive for the infection in primary care than white people, after accounting for other conditions of health.
The authors suggest their ethnicity results require caution because of the relatively small numbers in their study from minority ethnic groups.
There was a marked difference between people living in the most deprived and the least deprived areas.
Of the 668 people tested from the most deprived areas, 29.5% (197 people) were positive for the virus, compared to 7.7% (143 out of 1,855 people) in the least deprived areas.
Maybe people in urban areas tended to be more at risk than those in rural areas because of more opportunities for social mixing.
Of 1,816 individuals surveyed in urban areas, 26.2 percent (476 people) were positive, while 5.6 percent (111 out of 1,986 people) tested positive in rural areas.
Contrary to analyzes of severely ill patients receiving treatment in hospitals, chronic kidney disease and obesity were the only pre-existing health conditions which doctors could independently correlate with positive testing.
32.9 percent of those with chronic kidney disease tested positive (68 of 207 those), compared to 14.4 percent of those without the condition (519 of 3,595 people).
Although 13.2 percent of healthy-weight people tested positive (171 out of 1,296 people), 20.9 percent of obese people tested positive (142 out of 680 people).
As with other studies, males were more likely to test positive than females, and middle-aged adults were more at risk than kids.
18.4 per cent (296) of the 1,612 males tested were positive, while 13.3 percent of females tested positive (291 out of 2,190 tested).
18.5 percent tested positive (243 out of 1,316 people) among adults aged 40–64 years. Just 4.6 percent of children up to the age of 17 had positive test results (23 out of 499).
Is smoking protective?
Some of the most interesting results was that smokers were less likely than those who had never smoked to test positive for SARS-CoV-2.
11.4 percent (47 people) of 413 smokers tested positive compared with 17.9 percent of non-smokers (201 out of 1,125 people).
The authors caution: “Our findings should not be used to conclude that smoking prevents SARS-CoV-2 infection, or to encourage ongoing smoking, particularly given the well-documented harms from smoking to overall health, the potential for smoking to increase the severity of COVID-19 disease, and the potential alternative explanations for such findings.”
Smoking can affect the sensitivity of the test by reducing the concentration of virus particles in the nose and throat, the researchers note. Additionally, smokers may have a higher likelihood of having cough and thus may be more likely to submit for testing.
Bias in selection could potentially affect all the results because some groups are more or less likely to present themselves for testing.
Rachel Jordan and Peymane Adab, at the Institute of Applied Health Research, Birmingham University, UK, write comment article accompanying the paper:
“As U.K. Prepare to loosen lockdown measures; it is vital to know who is most at risk of infection. This research highlights the subgroups that are more susceptible for those with related symptoms, although we can not be sure why they are more susceptible. There is an urgent need for population level studies with testing among random samples of the general population (irrespective of symptoms), as well as accurate antibody tests of past infection.