April 20, 2024

Study Reveals Twice-Yearly Circulation of Coronaviruses in Malawi

New research led by the MRC-University of Glasgow Centre for Virus Research (CVR) has found that common human coronaviruses circulate twice yearly in Malawi, in contrast to annual winter peaks in more temperate climates. The study, published in The Journal of Infectious Diseases, provides insight into the circulation of seasonal coronaviruses in Africa, an area that often lacks epidemiological data on respiratory pathogens.

Human seasonal coronaviruses, which are closely related to SARS-CoV-2, typically cause mild flu-like illness but can occasionally lead to severe respiratory illness. The study, one of the largest of its kind, examined the circulation of four species of common seasonal coronaviruses between 2011 and 2017 in Blantyre, Malawi. PCR tests were conducted on nose and throat samples from over 6,000 individuals of all ages.

The findings revealed that all four seasonal human coronaviruses peaked twice a year in Malawi, although the timing of the highest circulation varied among the individual coronavirus species. This differs from their circulation in temperate climates, such as the UK, America, and Europe, where they tend to peak once a year, mostly during winter months.

The study included samples from individuals with both mild and severe acute respiratory illnesses, as well as asymptomatic individuals in a control group. Among adults, one of the circulating coronaviruses was associated with mild illness, while two were associated with severe illness. In children, all four human coronaviruses were equally likely to cause illness or an asymptomatic infection. The study also found that human coronaviruses were more frequently found together with other respiratory viruses in individuals with severe illness, compared to those with no or mild symptoms.

The research was a result of collaboration between the University of Glasgow and the Malawi-Liverpool-Wellcome Trust Clinical Research Programme, with involvement from Lancaster University, the University of Liverpool, and the US Centers for Disease Control and Prevention (CDC).

Dr. Antonia Ho, lead author of the study from the CVR, emphasized the importance of understanding the circulation patterns of human seasonal coronaviruses, as it may help predict how SARS-CoV-2 will circulate in the future. Dr. Ho also stressed the need to continue monitoring the circulation of human coronaviruses, including SARS-CoV-2, along with other respiratory viruses such as influenza and respiratory syncytial virus.

Dr. Dory Kovacs, first author from the University of Glasgow, expressed excitement over the collaboration and the opportunity to shed light on the epidemiology of seasonal viruses in an understudied geographical area.

This research provides valuable insights into the circulation patterns of coronaviruses in Africa and contributes to our understanding of respiratory illnesses in the region. By studying the behavior of common human coronaviruses in Malawi, we can gain greater understanding of how SARS-CoV-2 may circulate in Southern Africa in the future. Ongoing monitoring of respiratory viruses is crucial for effective public health measures and outbreak preparedness.

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