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The screening method represents a simple, quick, and practical tool for estimating vaccine effectiveness (VE) using routine disease surveillance and vaccine coverage data, even if these data cannot be linked. In Germany, where notification data, laboratory testing data, and vaccine coverage data cannot be linked due to strict data protection requirements, the screening method was used to assess COVID-19 VE continuously between July 2021 and March 2023. During this period, when Delta and Omicron variants circulated, VE estimates were produced in real-time for different age groups and clinical outcomes. Here we describe the country’s overall positive experience using the screening method, including its strengths and limitations, and provide practical guidance regarding a few issues, such as case definition stringency, testing behaviour, and data stratification, that require careful consideration during data analysis and the interpretation of the results.


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  1. World Health Organization (WHO). Evaluation of COVID-19 vaccine effectiveness: Interim guidance (17 March 2021). Geneva: WHO; 2021. Available from: https://www.who.int/publications/i/item/WHO-2019-nCoV-vaccine_effectiveness-measurement-2021.1
  2. Thomas HL, Andrews N, Green HK, Boddington NL, Zhao H, Reynolds A, et al. Estimating vaccine effectiveness against severe influenza in England and Scotland 2011/2012: applying the screening method to data from intensive care surveillance systems. Epidemiol Infect. 2014;142(1):126-33.  https://doi.org/10.1017/S0950268813000824  PMID: 23591102 
  3. Legrand J, Vergu E, Flahault A. Real-time monitoring of the influenza vaccine field effectiveness. Vaccine. 2006;24(44-46):6605-11.  https://doi.org/10.1016/j.vaccine.2006.05.063  PMID: 16806607 
  4. Remschmidt C, Rieck T, Bödeker B, Wichmann O. Application of the screening method to monitor influenza vaccine effectiveness among the elderly in Germany. BMC Infect Dis. 2015;15(1):137.  https://doi.org/10.1186/s12879-015-0882-3  PMID: 25887460 
  5. Seyler T, Bella A, Puzelli S, Donatelli I, Rizzo C, screening method working group. Estimating pandemic vaccine effectiveness in two Italian regions using the screening method, 2009-2010. Vaccine. 2012;30(2):109-11.  https://doi.org/10.1016/j.vaccine.2011.11.013  PMID: 22100893 
  6. Cohen AL, Taylor T Jr, Farley MM, Schaffner W, Lesher LJ, Gershman KA, et al. An assessment of the screening method to evaluate vaccine effectiveness: the case of 7-valent pneumococcal conjugate vaccine in the United States. PLoS One. 2012;7(8):e41785.  https://doi.org/10.1371/journal.pone.0041785  PMID: 22870248 
  7. Moline HL, Whitaker M, Deng L, Rhodes JC, Milucky J, Pham H, et al. Effectiveness of COVID-19 Vaccines in Preventing Hospitalization Among Adults Aged ≥65 Years - COVID-NET, 13 States, February-April 2021. MMWR Morb Mortal Wkly Rep. 2021;70(32):1088-93.  https://doi.org/10.15585/mmwr.mm7032e3  PMID: 34383730 
  8. Horváth JK, Ferenci T, Ferenczi A, Túri G, Röst G, Oroszi B. Real-Time Monitoring of the Effectiveness of Six COVID-19 Vaccines against Laboratory-Confirmed COVID-19 in Hungary in 2021 Using the Screening Method. Vaccines (Basel). 2022;10(11):1824.  https://doi.org/10.3390/vaccines10111824  PMID: 36366334 
  9. Mazagatos C, Monge S, Olmedo C, Vega L, Gallego P, Martín-Merino E, et al. , Working Group for the surveillance and control of COVID-19 in Spain, Working group for the surveillance and control of COVID-19 in Spain. Effectiveness of mRNA COVID-19 vaccines in preventing SARS-CoV-2 infections and COVID-19 hospitalisations and deaths in elderly long-term care facility residents, Spain, weeks 53 2020 to 13 2021. Euro Surveill. 2021;26(24):2100452.  https://doi.org/10.2807/1560-7917.ES.2021.26.24.2100452  PMID: 34142647 
  10. World Health Organization (WHO). COVID-19 vaccine effectiveness estimation using the screening method: Operational tool for countries. Geneva: WHO. 2022.
  11. Stoliaroff-Pepin A, Peine C, Herath T, Lachmann J, Hellenbrand W, Perriat D, et al. Vaccine effectiveness against severe COVID-19 during the Omicron wave in Germany: results from the COViK study. Infection. 2023;51(4):1093-102.  https://doi.org/10.1007/s15010-023-02012-z  PMID: 36913112 
  12. Stoliaroff-Pepin A, Peine C, Herath T, Lachmann J, Perriat D, Dörre A, et al. Effectiveness of vaccines in preventing hospitalization due to COVID-19: A multicenter hospital-based case-control study, Germany, June 2021 to January 2022. Vaccine. 2023;41(2):290-3.  https://doi.org/10.1016/j.vaccine.2022.11.065  PMID: 36509640 
  13. Harder T, Koch J, Vygen-Bonnet S, Külper-Schiek W, Pilic A, Reda S, et al. Efficacy and effectiveness of COVID-19 vaccines against SARS-CoV-2 infection: interim results of a living systematic review, 1 January to 14 May 2021. Euro Surveill. 2021;26(28):2100563.  https://doi.org/10.2807/1560-7917.ES.2021.26.28.2100563  PMID: 34269175 
  14. Harder T, Külper-Schiek W, Reda S, Treskova-Schwarzbach M, Koch J, Vygen-Bonnet S, et al. Effectiveness of COVID-19 vaccines against SARS-CoV-2 infection with the Delta (B.1.617.2) variant: second interim results of a living systematic review and meta-analysis, 1 January to 25 August 2021. Euro Surveill. 2021;26(41):2100920.  https://doi.org/10.2807/1560-7917.ES.2021.26.41.2100920  PMID: 34651577 
  15. Külper-Schiek W, Piechotta V, Pilic A, Batke M, Dreveton LS, Geurts B, et al. Facing the Omicron variant-how well do vaccines protect against mild and severe COVID-19? Third interim analysis of a living systematic review. Front Immunol. 2022;13:940562.  https://doi.org/10.3389/fimmu.2022.940562  PMID: 36091023 
  16. Robert Koch Institute (RKI). Monitoring des COVID-19-Impfgeschehens in Deutschland: Monatsbericht [Monthly monitoring report on COVID-19 vaccination in Germany]. Edited by Department of Infectious Disease Epidemiology. Berlin: RKI. 2022-2023.
  17. Farrington CP. Estimation of vaccine effectiveness using the screening method. Int J Epidemiol. 1993;22(4):742-6.  https://doi.org/10.1093/ije/22.4.742  PMID: 8225751 
  18. Mary-Krause M, Mary JY, Valleron AJ. Conditions of validation and use of the screening method for vaccine efficacy evaluation. Rev Epidemiol Sante Publique. 1993;41(2):155-60. PMID: 8493394 
  19. Faensen D, Claus H, Benzler J, Ammon A, Pfoch T, Breuer T, et al. SurvNet@RKI--a multistate electronic reporting system for communicable diseases. Euro Surveill. 2006;11(4):614.  https://doi.org/10.2807/esm.11.04.00614-en  PMID: 16645245 
  20. Perumal N, Steffen A, Ullrich A, Siedler A. Impact of COVID-19 immunisation on COVID-19 incidence, hospitalisations, and deaths by age group in Germany from December 2020 to October 2021. Vaccine. 2022;40(21):2910-4.  https://doi.org/10.1016/j.vaccine.2022.04.002  PMID: 35428498 
  21. Robert Koch Institute. Digitales Impfquotenmonitoring zur COVID-19-Impfung [COVID-19 vaccination coverage surveillance in Germany]. Available at www.rki.de/covid-19-impfquoten.
  22. Sievers C, Zacher B, Ullrich A, Huska M, Fuchs S, Buda S, et al. SARS-CoV-2 Omicron variants BA.1 and BA.2 both show similarly reduced disease severity of COVID-19 compared to Delta, Germany, 2021 to 2022. Euro Surveill. 2022;27(22):2200396.  https://doi.org/10.2807/1560-7917.ES.2022.27.22.2200396  PMID: 35656831 
  23. Relan P, Motaze NV, Kothari K, Askie L, Le Polain de Waroux O, Van Kerkhove MD, et al. Severity and outcomes of Omicron variant of SARS-CoV-2 compared to Delta variant and severity of Omicron sublineages: a systematic review and metanalysis. BMJ Glob Health. 2023;8(7):e012328.  https://doi.org/10.1136/bmjgh-2023-012328  PMID: 37419502 
  24. Stowe J, Andrews N, Kirsebom F, Ramsay M, Bernal JL. Effectiveness of COVID-19 vaccines against Omicron and Delta hospitalisation, a test negative case-control study. Nat Commun. 2022;13(1):5736.  https://doi.org/10.1038/s41467-022-33378-7  PMID: 36180428 
  25. World Health Organization (WHO). Evaluation of COVID-19 vaccine effectiveness in a changing landscape of COVID-19 epidemiology and vaccination (Second addendum to Evaluation of COVID-19 vaccine effectiveness: Interim guidance). Geneva: WHO. 2022.
  26. Betsch C, Eitze S, Sprengholz P, Korn L, Shamsrizi P, Geiger M, et al. Ergebnisse aus dem COVID-19 Snapshot MOnitoring COSMO. Stand 02.12.22. [Results from the COVID-19 Snapshot Monitoring (COSMO) study: Update from December 2022]; Dec 2022. German. Available from: https://projekte.uni-erfurt.de/cosmo2020/files/COSMO_W70.pdf
  27. UK Health Security Agency (UKHSA). COVID-19 vaccine quarterly surveillance reports (September 2021 to October 2023). London: UKHSA. 2023.
  28. Meyer ED, Sandfort M, Bender J, Matysiak-Klose D, Dörre A, Bojara G, et al. BNT162b2 vaccination reduced infections and transmission in a COVID-19 outbreak in a nursing home in Germany, 2021. Influenza Other Respir Viruses. 2023;17(1):e13051.  https://doi.org/10.1111/irv.13051  PMID: 36082799 
  29. Barda N, Dagan N, Cohen C, Hernán MA, Lipsitch M, Kohane IS, et al. Effectiveness of a third dose of the BNT162b2 mRNA COVID-19 vaccine for preventing severe outcomes in Israel: an observational study. Lancet. 2021;398(10316):2093-100.  https://doi.org/10.1016/S0140-6736(21)02249-2  PMID: 34756184 

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