Researchers from John’s Hopkins Center for Excellence in Influenza Research and Response (JH-CEIRR) evaluated the burden of respiratory viruses in rural Zambia during the second year of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Dr. Catherine Sutcliffe, a research professor and lead author, joined by other JH-CEIRR researchers Dr. Katherine Fenstermacher, Dr. Richard Rothman, Dr. Andrew Pekosz, Dr. Yukari Manabe, and Dr. Edgar Simulundu recently published their work in International Society for Infectious Diseases Regions. Public health and social measures implemented to control the spread of SARS-CoV-2 in 2020 also impacted the transmission of other respiratory viruses, including influenza viruses and respiratory syncytial virus (RSV). Following the ease of restrictions, RSV and influenza circulation resumed with off-season transmission and delayed seasons reported in North America, Europe, and Asia. However, although there is significant morbidity and mortality for respiratory infections in sub-Saharan Africa, there is limited data available for the region regarding trends for respiratory infections after restrictions were eased.
In 2018, the JH-CEIRR established surveillance for respiratory infections in rural Zambia to help in understanding the epidemiology and burden of respiratory pathogens in a region that is widely underrepresented in global surveillance networks. As surveillance is ongoing, the authors were able to compare the landscape of respiratory viruses before and during the SARS-CoV-2 pandemic in this region with the objective of evaluating the burden and pattern of these viruses.
Macha Hospital in Southern Province, Zambia was chosen as the location for respiratory surveillance, providing care for a population of over 150,000 individuals primarily consisting of subsistence farmers. All patients attending the outpatient department of the hospital were screened for influenza-like illness (ILI). On a weekly basis an age-stratified sample of patients positive for ILI were approached for enrollment, upon which a questionnaire was administered to collect patients’ personal and medical history. A nasopharyngeal swab was also collected at the time of enrollment and placed in universal transport media so it could be tested for influenza A and B, RSV, adenovirus, human metapneumovirus, human rhinovirus/enterovirus, parainfluenza virus 1-4, and various coronaviruses, including SARS-CoV-2.
The first SARS-CoV-2 infection in Zambia was identified in December 2020. The authors found that there was a dramatic decline in influenza and RSV in rural Zambia in 2020 that was reversed once public health restrictions were lifted in the region. After restrictions were lifted, influenza and RSV patterns mirror those observed in 2019 prior to the onset of the SARS-CoV-2 pandemic. Off-season transmission was not observed in Zambia after measures were lifted. This may be due to resumption of normal travel and gatherings during the time of year these viruses usually circulated prior to the start of the SARS-CoV-2 pandemic. Other respiratory viruses circulated consistently from 2019 to 2021, with no interruption from the measures taken during the SARS-CoV-2 pandemic.
The findings from Sutcliffe et al. (2023) underscore the importance of ongoing surveillance in underrepresented regions of the world. JH-CEIRR researchers showed how vital collecting systemic information regarding the circulation and transmission of respiratory viruses is, especially through extenuating circumstances such as the SARS-CoV-2 pandemic, to better understand the continuously changing context of these diseases.