C- Consensus communication with doctors is constantly increasing vaccinations against Covid-19 disease – Nature

Complementary survey among physicians

To gather physicians’ opinions on COVID-19 vaccines, we conducted a survey in partnership with CMC, to increase coverage of the medical community. The survey was carried out online in February 2021. Since membership in the CMC is mandatory, the CMC has a list of contacts for all physicians in the country. CMC contacted all physicians who communicate with CMC electronically (70%) and asked them to participate in a short survey using the Qualtrics platform. Of the clinicians contacted, 9,650 (24%) answered the questionnaire. Doctors in our sample work in all regions of the country, on average 52 years old, 64% are female and 62% have more than 20 years of experience. A comparison of the characteristics of physicians in our sample and all physicians in the Czech Republic is presented in Supplementary Table 1.

main experience

a sample

Our main sample consisted of 2,101 participants in the ‘Life During an Epidemic’ online longitudinal dataset, organized by the authors in collaboration with PAQ Research and the NMS Survey Agency. In March 2020, the committee began providing real-time data on developments in economic, health and social conditions during the COVID-19 pandemic. We used data from 12 consecutive waves of data collection conducted at 3-4 week intervals between mid-March and the end of November 2021.

The information intervention was carried out on March 15, 2021, which we called wave 0. The sample from wave 0 is the “base sample” (n= 2,101, 1,052 female and 1,049 male participants, mean age 52.9 years (s.d. = 15.98), youngest 18 years of age, oldest 92 years of age). The base sample broadly represents the adult Czech population in terms of sex, age, education, region, municipality size, employment status before the COVID-19 pandemic, age x gender and age x education. Prague and municipalities with a population of over 50,000 have an increase in samples (200% increase). Sample statistics are presented in Expanded Data Table 1. The sample is close to being representative of the adult Czech population in terms of attitudes toward COVID-19 vaccines. The evolution of the proportion of subjects who received vaccination in the control condition closely mimics actual vaccination rates in the Czech Republic (Extended Data Fig. 1), when we evaluated the observations in our sample to be representative in terms of observable characteristics.

An important feature of the panel is that participants agreed to be interviewed regularly, and the response rate is high throughout the study period: it ranges from 76% to 92% in individual follow-up waves, and 86% for the last wave implemented. At the end of November 2021. Of the participants, 1212 (58%) participated in all twelve waves of data collection: they constitute the ‘fixed sample’. Thus, in the analysis, we report the main findings of (1) all participants from the base sample who responded in a given wave, which we refer to as the “whole sample,” and (2) the “constant sample,” made up of individuals who participated in all waves. The 12, eliminating the potential role of variations in samples across waves and making it easier to measure the dynamics of treatment effects.

enter information

At wave 0, participants were randomly assigned to either the consensus condition (n= 1,050) or control condition (n= 1,051). In the case of consensus, they were informed that CMC conducted a large survey of nearly 10,000 physicians from across the country to collect their opinions on COVID-19 vaccines. They were also informed that opinions were similar for physicians of different races, ages, and regions. Then, participants were shown three charts illustrating the distribution of clinicians’ responses regarding their confidence in vaccines, their willingness to vaccinate themselves, and the intent to recommend the vaccine to their patients. Each of the diagrams was supplemented by a short written summary. Exact wording and diagrams are provided in Section 3.3 of the Supplementary Information. In the control condition, participants received no information about the physicians’ survey.


Before information entered wave 0, we elicited preconceived beliefs about clinician opinions to identify misconceptions about clinician opinions. Specifically, participants were asked to estimate (1) the percentage of physicians in the Czech Republic who trust approved vaccines, and (2) the percentage of physicians who have been vaccinated or intend to vaccinate themselves. Later, in wave 1, we extrapolated later beliefs to estimate whether subjects in the consensus condition actually updated their beliefs about clinicians’ opinions based on the information provided. In each of the 12 waves, we asked respondents to report whether they had received a vaccine against COVID-19. The main outcome variable ‘vaccinated’ equals one if the respondent reports having received at least one dose of a vaccine against COVID-19.

In the analysis, we report two main regression specifications: (1) linear probability regression adjustment for previously recorded covariates: sex, age (6 categories), family size, number of children, region (14 regions), and city size (7) classes ) education (4 categories), economic status (7 categories), family income (11 categories), and prior vaccination intentions, and (ii) double-choice for a lasso linear regression by selecting from a broader set of controls in Expanded Spreadsheet 1, including vaccine prior uptake and beliefs About the opinions of doctors.

Additional data to check vaccination status

We collected two additional data sets to verify vaccination status reported in the main data set.

Third Party Verification

First, we used data collected for us by an independent third party. We took advantage of the fact that different survey agencies had access to the panel that our respondents were sampled from (the Czech National Panel). Although the main data collection process was performed by one agency (NMS), we partnered with another agency (STEM/MARK) to include a question about vaccination status in a survey carried out on its behalf among the same sample. As the survey agency, the graphic interface and survey subject matter were different from our main data collection, we believe that respondents considered the two surveys to be completely independent of each other, and thus it is unlikely that the experimenter’s request had a role in the second survey. The response rate was high (92.8%) and independent of treatment (Extended Data Table 6). Out of the 1,801 participants in wave 11, 1,672 also took part in a third-party verification survey which was carried out two weeks later. This allowed us to compare the reported vaccination status at the individual level for the vast majority of the sample, and to test whether consensus influences the level of consistency in vaccination reporting across surveys.

Certificate Verification

The second verification links the reported vaccination status to official proof of vaccination. We took advantage of the fact that all vaccinated people receive an EU digital COVID certificate issued by the Czech Ministry of Health, which was often used as a screening tool at the time of data collection. We collected vaccination certificate data among respondents from the full sample who (i) participated in wave 11, and (ii) reported having received at least one dose of COVID-19 vaccine in wave 11 (n= 1414). We asked respondents if they had the certificate with them. Of the participants, 96% confirmed that they had the certificate with them, and this percentage is very similar across the compliance and control conditions (χ2(1,n= 1414) = 0.999, s= 0.318). Certification holders were asked to write several specific pieces of information about the applied vaccine that a person without a certification would be unlikely to know (eg, the correct answer for those who received a vaccine from Pfizer/Biontech is ‘SARS-CoV-2 mRNA’). An evaluation of the written transcript by independent evaluators indicates that, provided they obtained certification, over 94% of respondents actually considered the certification when answering our detailed questions. This rate is again very similar across conditions (χ2(1,n=1364) = 0.473, s= 0.492).

More details on both the validation procedures and results are in the Supplementary Information.

Ethics approval

The research study was approved by the Research Ethics Committee of the Charles University School of Social Sciences. Participation was voluntary and all respondents gave their consent to participate in the survey.

Report summary

More information about the research design is available in the Nature Research report summary linked to this paper.

2022-06-01 15:12:55

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