BACKGROUND: The COVID-19 pandemic has disrupted HIV and sexually transmitted infection (STI) testing accessibility. We sought to assess the longer-term impacts of COVID-19 on HIV and STI testing and diagnosis in Oregon. METHODS: First, we examined HIV, Neisseria gonorrhoeae / Chlamydia trachomatis (CT), and syphilis tests conducted at the Oregon State Public Health Laboratory (public sector) and a large commercial laboratory (private sector) and HIV, N. gonorrhoeae , CT, and primary and secondary (P&S) syphilis diagnoses in Oregon from January 1, 2019, to December 31, 2021. We compared monthly testing and diagnosis rates in 5 prespecified periods: pre-COVID-19 (January 2019-February 2020), stay-at-home order (March 2020-May 2020), reopening (June 2020-December 2020), vaccine availability (January 2021-June 2021), and Delta/early Omicron spread (July 2021-December 2021). Second, we calculated the number of HIV and STI diagnoses per test in the public and private sectors. Finally, we used seasonal autoregressive integrated moving average models to predict expected HIV and STI diagnoses for comparison to those observed. RESULTS: Both public and private sector HIV and bacterial STI testing fell to nadirs in April 2020 with incomplete recovery to 2019 levels by the close of 2021. Compared with pre-COVID-19, public sector and private sector testing was significantly lower in all subsequent periods. Compared with pre-COVID-19, P&S syphilis cases were 52%, 75%, and 124% greater in the reopening, vaccine availability, and Delta/early Omicron periods, respectively. From March 2020 to December 2021, we observed an excess of P&S syphilis cases (+37.1%; 95% confidence interval, 22.2% to 52.1%) and a deficit in CT cases (-10.7%; 95% confidence interval, -15.4% to -6.0%). CONCLUSIONS: By December 2021, HIV/STI testing had not recovered to pre-COVID-19 levels, and HIV/STI continues to be underdiagnosed. Despite decreased testing, P&S syphilis cases have increased substantially.