Malaria amidst the COVID-19 pandemic in Gabon: an application of autoregressive integrated moving average (ARIMA) models within an interrupted time series (ITS) framework to hospital-based data.

Background: Coinciding with the SARS-CoV-2 pandemic, malaria cases and malaria-related deaths increased globally between 2020 and 2022. However, evidence linking the pandemic to increased malaria burden remains ambiguous. We assessed the extent to which an observed malaria resurgence in Lambaréné, Gabon, can be associated with pandemic-related disruptions in malaria control programmes.

Methods: Using observational data from two tertiary referral hospitals, spanning 2018 to early 2023, we applied autoregressive integrated moving average (ARIMA) models in an interrupted time series (ITS) framework to test for changes in trends and levels following the onset of the pandemic. The primary outcome is the monthly malaria diagnosis rate (per 1000 all-cause hospital diagnoses). As a sub-analysis, we focused on monthly maternal malaria incidence.

Results: Following an initial drop (-47.32, P = 0.031), potentially due to risk-averse behaviours, the malaria diagnosis rate gradually and concavely increased (linear term: 7.32, P = 0.001; squared term: -0.19, P = 0.001) to a peak above pre-pandemic levels. Additional analyses suggest that this resurgence was likely driven by disruptions to malaria control activities and a waning efficacy of malaria control tools administered pre-pandemic. Conversely, a resurgence in maternal malaria incidence was not estimated.

Conclusion: Findings align with several national and global descriptive reports, but add a more detailed understanding of underlying dynamics, therefore reinforcing the importance of maintaining malaria control in the general population. The absence of a meaningful increase in maternal malaria provides some reassurance that malaria in pregnancy-specific control remained unchanged during the SARS-CoV-2 pandemic. However, observed peaks in post-pandemic maternal malaria incidence should raise concerns given the risks that malaria poses to this group.