Sexually Transmitted Infections, the Epidemic That Persists After the COVID-19 Pandemic: a Time-series Analysis of the Primary Care Electronic Health Records Covering About 5 Million People in Catalonia

Background: The COVID-19 pandemic and related control measures have affected the diagnosis of other diseases, including sexually transmitted infections (STI). Our aim is to analyse the impact of the COVID-19 pandemic on the incidence of STI diagnosed in primary care.Methods: Time-series study of STI, using data from primary care electronic health records in Catalonia (Spain) from January 2016 to March 2021. We obtained the monthly expected incidence of STI using a temporary regression, where the response variable was the incidence of STI from 2016 to 2019 and the adjustment variables were the trend and seasonality of the time series. Excess or reduction of STI were defined as the number of observed minus the expected cases, globally and stratified by age, sexe, type of STI and socioeconomic status.Results: Between March 2020 and March 2021 we observed a reduction of 20.2% (95% CI: 13.0% to 25.8%) on STI diagnoses compared to the expected. This reduction was greater during the lockdown period (-39%), in women (-26.5%), in people aged under 60 years (up to -22.4% in people aged 30-59 years), less deprived areas (-24%) and some types of STI, specially chlamydia (-32%), gonorrhea (-30.7%) and HIV (-21.5%). Conversely, syphilis and non-specific STI were those with lesser reductions with -3.6% and -7.2%, respectively,Conclusions: The COVID-19 pandemic has impacted on STI incidence, reducing the number of diagnoses performed in primary care and raising concerns about future evolution of STI trends. Those STI that are less symptomatic or diagnosed through screening will deserve special attention regarding potential diagnostic delays.