Footnotes

• Handling editor Anna Maria Geretti

• Twitter @sexresearchnow, @KMitchinGlasgow, @fienige

• Contributors The paper was conceived by DM, PS, CHM, KM and NF. Statistical analysis was done by DM with input from MW. DM and NF wrote the first draft with further contributions from PS, CHM and KM. PS and CHM are principal investigators (PIs) on Natsal, while NF and KM are PIs on Natsal-COVID. NF is responsible for overall content as the guarantor.

• Funding The Natsal Resource, which is supported by a grant from the Wellcome Trust (212931/Z/18/Z), with contributions from the Economic and Social Research Council (ESRC) and National Institute for Health Research (NIHR), supports the Natsal-COVID Study in addition to funding from the UCL Coronavirus Response Fund and the University of Glasgow MRC/CSO Social and Public Health Sciences Unit (core funding, MC_UU_00022/3; MC_UU_00022/2; SPHSU17; SPHSU18).

• Competing interests NF served as an associate editor for BMJ STIs until May 2023. No other competing interests reported.

• Provenance and peer review Not commissioned; internally peer reviewed.