Has the COVID-19 pandemic wiped out the seasonality of outpatient antibiotic use and influenza activity? A time-series analysis from 2014 to 2021

Clin Microbiol Infect. 2022 Jan 10;S1198-743X(21)00730-8. doi: 10.1016/j.cmi.2021.12.022. Online ahead of print.


Objectives: To assess the influence of the emergence of SARS-CoV-2 and the implementation of public health measures on seasonality of outpatient antibiotic use and its possible association with the incidence of influenza.

Methods: We performed a time-series ecological study in 1,516 primary care centres of Andalusia, Spain, comparing the COVID-19 period (April 2020 to March 2021) with the six previous years. We assessed the number of packs and DDD per 1,000 inhabitants of antibacterials and key antibiotics commonly used for acute respiratory tract infections (ARTIs) and the number of influenza-positive cases per 100,000 inhabitants. We calculated the correlation between variables and analysed the seasonal patterns and differences in quarterly antibiotic use.

Results: For all the quarters, a significant correlation was observed between influenza activity and antibiotic use (Spearman's r=0.94; p<0.001). Before the pandemic period, both variables presented similar seasonal patterns. After the start of the pandemic, the influenza activity was suppressed and the antibiotic use pattern flattened off turning into a straight line (R2=0.96; p=0.022) with a quarterly percentage of change of 3.9% (p=0.007). Total antibiotic use and antibiotics used for treating ARTIs showed significant reductions in all quarters compared to the previous year (p<0.01).

Conclusions: The COVID-19 pandemic has strongly influenced the seasonality of antibiotic use in primary care. The decline in respiratory viruses, for which the influenza virus is a major player and may act as a proxy, is proposed as a reason for the flattening out of the seasonal fluctuations of outpatient antibiotic use in our region.