A Nationwide Observational Study of Chlamydia trachomatis Infections in Denmark during the COVID-19 Pandemic

  1. Paula L. Hedley
  2. Steen Hoffmann
  3. Ulrik Lausten-Thomsen
  4. Marianne Voldstedlund
  5. Karsten Dalsgaard Bjerre
  6. Anders Hviid
  7. Lone Krebs
  8. Jørgen S. Jensen
  9. Michael Christiansen

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Abstract

The aim of this study was to determine whether COVID-19 restrictions had an impact on Chlamydia trachomatis infections compared with 2018 and 2019. A retrospective nationwide observational study was performed using monthly incidences of laboratory-confirmed chlamydia cases and number of tests, obtained from Danish national surveillance data. Testing rates and positivity rates were compared using Poisson and logistic regression. The first Danish COVID-19 lockdown (12 March to 14 April 2020) resulted in a reduction in the number of chlamydia tests performed (rate ratio 0.72, 95% confidence interval  0.71–0.73) and a consequent reduction in the number of laboratory-identified cases (66.5 vs 88.3 per 100,000 population during the same period in 2018 to 2019). This period was followed by a return of testing and test positivity close to the level seen in 2018 to 2019. The second Danish COVID-19 lockdown (17 December to 31 March 2021) resulted in crude incidence rates of laboratory-confirmed chlamydia infection that were similar to the crude incidence rates seen during same period in 2018 to 2019. In conclusion, the Danish COVID-19 restrictions have had negligible effects on laboratory-confirmed C. trachomatis transmission.

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  1. Version published to 10.2340/actadv.v102.2324
  2. ScreenIT

    SciScore for 10.1101/2021.06.30.21259819: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: Ethics: All data were aggregate and most from publicly available sources supplemented with national surveillance data, so approvals from neither scientific ethics committees nor Data Authorities were necessary as per Danish law and regulations.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    Data sources: Numbers of laboratory confirmed C. trachomatis infections were obtained via extracts from MiBa via the webportal at Statens Serum Institut.10 11 The monthly number of C.trachomatis laboratory tests performed since January 2018 were obtained from national surveillance data extracted from MiBa12.
    Numbers
    suggested: (BioNumbers, RRID:SCR_002782)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    The lack of relation between limitations in mobility and social interaction and chlamydia incidence may be a result of the extent to which dating apps were used, particularly important among young adults.21 28 In conclusion, the first Danish lockdown period was associated with a decrease in testing and a subsequent reduced incidence of laboratory confirmed chlamydia. This was not seen in the second lockdown period and the intervening period of eased restrictions. Thus, the period of COVID-19 restrictions, with its significant effects on behaviour, was not associated with appreciable changes in chlamydia transmission.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2021.06.30.21259819v1 on medRxiv