In Africa, infections rise whereas COVID-19 severity remains low
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Screening in Mali, where 60% of people have been infected with SARS-CoV-2, found no difference in the rates of respiratory or gastrointestinal symptoms among people who had been infected vs. people who were not, according to a study.
John Woodford, MD, a malaria researcher at the National Institute of Allergy and Infectious Diseases, and colleagues conducted an analysis of clinical information during a two-visit serosurvey at three sites in urban and rural locations in Mali. Their findings were presented at the American Society of Tropical Medicine & Hygiene meeting.
The first study visit, which included 2,533 participants, was conducted from July through October 2020, before malaria season. The second was completed in January 2021, just after malaria season, with 2,672 participants.
At the first visit, when comparing participants who were seronegative vs. those who were seropositive, the researchers found that systemic symptoms were more common among those who were seropositive, such as fever (8.5% vs. 4%), chills (1.7% vs. 0.4%), myalgia (3.5% vs. 0.7%) and headache (11% vs. 3.7%). During the second visit, after malaria season, just chills (3.7% vs. 2.1%) and fatigue (4.3% vs. 2.5%) were more common among those who were seropositive.
Further, “respiratory and gastrointestinal symptoms did not clearly differ based on serostatus at either visit,” the researchers reported.
“This is just not the level of symptoms, complications, hospitalization and deaths you see in a population in the United States that has experienced such a high rate of exposure,” Woodford said in a press release. “Like the rest of sub-Saharan Africa, the population of Mali is relatively young. But this comparatively low burden of COVID-19 disease remained unchanged, even when we adjusted for age.”
The researchers said COVID-19 rates may fall to background levels during malaria transmission.
‘Malaria may have a protective effect’
In another study presented at the meeting, Jane Achan, PhD, a senior research advisor at the Malaria Consortium, and colleagues assessed malaria infections among hospitalized patients with COVID-19 in Uganda. They found that people with high malaria exposure rates were less likely to have severe COVID-19.
“We went into this project thinking we would see a higher rate of negative outcomes in people with a history of malaria infections because that’s what was seen in patients coinfected with malaria and Ebola,” Achan said in the release. “We were actually quite surprised to see the opposite — that malaria may have a protective effect.”
The researchers’ assessment of 597 hospitalized patients showed that those with low malaria exposure had a higher frequency of severe COVID-19 infection (30.2%) and a higher burden of comorbidities like hypertension (30.2%) and diabetes (22.6%), and death (3.8%). Just 5% of patients with high exposure to malaria had a severe case of COVID-19, they found.
In participants with no comorbidities, those with low malaria exposure still had a severity rate higher than those with high malaria exposure (18.2% vs. 2%).
Worse outcomes for Native Americans
A third study by Douglas J. Perkins, PhD, director of the University of New Mexico School of Medicine Center for Global Health, and colleagues showed that Native American populations were more at risk for severe COVID-19 infection.
Perkins’ team conducted an analysis of 94 patients with COVID-19, including 45.7% who identified as Native American. They defined severe infection as elevated blood viral loads, which was more commonly observed among Native Americans (OR = 7.46; 95% CI, 2.2-25.29), according to findings presented at the meeting.
SARS-CoV-2 peripheral blood, or viremia, was higher among Native Americans cumulatively over the course of 14 days. Native American ancestry was associated with a greater risk for having viremia (OR = 4.73; 95% CI, 1.67-13.43). Viremia during hospitalization was associated with severe disease (OR = 9.19; 95% CI, 3.33-25.34)
“These findings may explain, at least in part, the disproportionate disease burden of COVID-19 witnessed in this population,” Douglas and colleagues wrote. “It will be important to define the biological/molecular basis of these virological findings in future studies to design interventions for improved clinical outcomes.”
References:
Achan J, et al. Abstract 0029. Presented at: American Society of Tropical Medicine & Hygiene Annual Meeting; Nov. 17-21, 2021; virtual.
Perkins DJ, et al. Abstract 1384. Presented at: American Society of Tropical Medicine & Hygiene Annual Meeting; Nov. 17-21, 2021; virtual.
Woodford J, et al. Abstract 0906. Presented at: American Society of Tropical Medicine & Hygiene Annual Meeting; Nov. 17-21, 2021; virtual.
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Woodford J, et al. Abstract 0906. Presented at: American Society of Tropical Medicine & Hygiene Annual Meeting; Nov. 17-21, 2021; virtual.
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