Africa: Malaria Exposure May Have Led to Mild Covid-19 in Africa

Africa: Malaria Exposure May Have Led to Mild Covid-19 in Africa


Special Feature — When COVID-19 swept the globe in early 2020, health experts braced for devastation in Africa.

The continent’s healthcare systems, already stretched thin by endemic diseases like malaria, seemed ill-equipped to handle a new pandemic. Yet as the virus spread, a puzzling pattern emerged – many African countries reported lower COVID-19 severity rates than their counterparts in Europe and North America.

Dr. Jane Achan, a pediatrician and Principal Advisor at Malaria Consortium who oversees research across Africa and Southeast Asia, suspected there might be more to this story than healthcare infrastructure alone.

Her hypothesis led to groundbreaking research that would challenge assumptions about disease interactions and reveal an unexpected relationship between malaria exposure and COVID-19 outcomes.


Follow us on WhatsApp | LinkedIn for the latest headlines

“You recall that there was significant alarm around how Africa would manage this pandemic, given the challenges in healthcare, but we did realise that overall, because of high exposure to malaria in some settings, many of the patients with COVID-19, of course, seem to have a milder manifestation,” Dr. Achan said.

In their first study of 600 COVID-19 patients, the Malaria Consortium’s research team found a clear pattern. “Individuals who had a high previous exposure to malaria tended to be largely asymptomatic or have mild symptoms of COVID-19, whereas individuals who had a low previous exposure to malaria had very severe symptomatology of COVID-19.”

The implications were striking. While about 12% of patients had concurrent infections with both diseases, those who had battled malaria multiple times in the past seemed better equipped to handle COVID-19. “Many of them ended up in ICU, but also had prolonged hospitalisation,” Dr. Achan said about patients with low malaria exposure, contrasting sharply with those who had repeatedly faced the mosquito-borne disease.

The science behind the protection

The mechanism behind this protection appears to be immunological.

“When you get malaria, your body mounts an immunological response that protects you from either progressing to severe clinical disease or prevents the parasites from causing any disease. We believe there are correlations in the immunological response to malaria that may have contributed to protection in individuals who had COVID,” Dr. Achan explains.

This primed immune system may offer cross-protection against COVID-19 through two key pathways. First, the immunological response developed against malaria could provide broader protection against viral infections. Second, malaria exposure modulates cytokine responses – the same inflammatory molecules that cause severe tissue damage in COVID-19.

“One of the things that malaria does… it also modulates your cytokine response, and we think that maybe this co-infection or immunological relationship could have modulated the cytokine response in these individuals, such that the tissue destruction was lower because of the modulatory effect of your previous exposure to malaria,” Dr. Achan elaborates.

The study revealed that those with high previous malaria exposure “tended to have asymptomatic illness or mild illness, did not require ICU admission, and then also tended to have a lower risk of mortality compared to those that had had a low previous exposure to malaria”.

The findings filled a crucial knowledge gap, explaining the “potential explanation as to why COVID-19 may have manifested differently on the African continent” compared to the Global North. However, the research team faced an unexpected challenge in communicating their results.

“We struggled a bit with ensuring that the study findings are not misunderstood, because in some of the press, they actually thought: ‘Oh, we must now drop malaria protection and ensure that we are protected from COVID’,” Dr. Achan said. “The excitement around the findings was much higher than we anticipated,” requiring careful messaging to prevent dangerous misinterpretation.

The study helped explain “some of the differences that were observed at the time in terms of the clinical manifestation of COVID in the context of Africa, where malaria burden is high, and also what we saw, for example, in the European countries like Italy, where, you know, there was very severe disease, and the burden and the magnitude of mortality was very high”, she said.

Understanding disease interactions

Dr. Achan’s research underscores a fundamental principle in global health: diseases don’t exist in isolation. “When new diseases come in, they come in a context where there are other endemic diseases,” she reflects. “So in the African continent, the endemic disease is malaria. And when new diseases come in, I think it’s of important public health significance that we understand how these diseases relate.”

Her work provided crucial insights into why the pandemic evolved differently across different global contexts. The study demonstrated “the importance of really understanding co-infections. When new diseases come in, they come in a context where there are other endemic diseases.”

Interestingly, Dr. Achan’s follow-up research revealed that COVID-19 survivors developed protective behaviors against malaria. “The experience of acute COVID illness changed patient behavior so significantly that they tended to present more frequently for any illness to the hospital,” she said.

This behavioral shift proved beneficial: “In the second study, we found a lower risk of malaria among the people who had suffered from COVID in the past.” Survivors were “using the malaria prevention more so… overwhelmingly, all of them are sleeping under the mosquito nets compared to the other population.”