eTable 4. Population-based studies on health literacy.

Study	Time of measurement	Subject	Proportion of low health literacy
HLS-GER 1	July/August 2014	Representative study to establish the health literacy of the population in Germany N = 2000 (aged 15 and above)	54.3%
HLS-GER 1‘	August/September 2020	Establishing the health literacy of the population in Germany over time N = 504 (aged 18 and above) Direct comparison with HLS-GER 1	64.2%
HLS-GER 2	December 2019/ January 2020	Extended representative study on health literacy of the population in Germany N = 2000 (aged 18 and above) Advanced methods	58.8%
HLS-GER 2‘	September/October 2020	Additional survey to HLS-GER 2: Health literacy during the corona pandemic and trend analysis N = 500 (aged 18 and above) Direct comparison with HLS-GER 2	55.9%

Direct comparison HLS-GER 1 vs. HLS-GER 1‘ (2014/2020) (22). This comparison shows that health literacy in the population in Germany has deteriorated. Since this comparison is based on the same survey and analysis methods, it provides the most reliable evidence of the deterioration.

HLS-GER 2 with the added survey HLS-GER 2‘ (both from 2020; conducted before and during the corona pandemic using advanced survey and analysis methods) (7). Even with the advanced methods, HLS-GER 2 still indicates that health literacy continues to deteriorate. A direct comparison of the results of the HLS-GER 2 versus HLS-GER 2’ shows that health literacy has slightly improved during the corona pandemic (7).

HLS-GER, Health Literacy Survey Germany