Background Epidemiological data indicate that a large part of population needs to be vaccinated to achieve herd immunity. Hence, it is of high importance for public health officials to know whether people are going to get vaccinated for COVID-19. The objective of the present study was to examine the willingness of adult residents in Greece to receive a COVID-19 vaccine. Methods A cross-sectional was survey conducted among the adult general population of Greece between April 28, 2020 to May 03, 2020 (last week of lockdown), using a mixed methodology for data collection: Computer Assisted Telephone Interviewing (CATI) and Computer Assisted web Interviewing (CAWI). Using a sample size calculator, the target sample size was found to be around 1000 respondents. To ensure a nationally representative sample of the urban/rural population according to the Greek census 2011, a proportionate stratified by region systematic sampling procedure was used to recruit particpants. Data collection was guided through a structured questionnaire. Regarding willingness to COVID-19 vaccination, participants were asked to answer the following question: “If there was a vaccine available for the novel coronavirus, would you do it?” Results Of 1004 respondents only 57.7% stated that they are going to get vaccinated for COVID-19. Respondents aged > 65 years old, those who either themselves or a member of their household belonged to a vulnerable group, those believing that the COVID-19 virus was not developed in laboratories by humans, those believing that coronavirus is far more contagious and lethal compared to the H1N1 virus, and those believing that next waves are coming were statistically significantly more likely to be willing to get a COVID-19 vaccine. Higher knowledge score regarding symptoms, transmission routes and prevention and control measures against COVID-19 was significantly associated with higher willingness of respondents to get vaccinated. Conclusion A significant proportion of individuals in the general population are unwilling to receive a COVID-19 vaccine, stressing the need for public health officials to take immediate awareness-raising measures.

INTRODUCTION Vaccination against the flu is the best method for the prevention of illness by influenza viruses. The objective of this study was to assess the impact of the COVID-19 pandemic on the seasonal influenza vaccination attitudes in Greece and to identify factors associated with a positive change in participants' choice to vaccinate against the flu. METHODS This is a sub-analysis of a cross-sectional nationwide survey (n=1004) that was conducted between 28 April and 3 May 2020 using a mixed methodology for data collection: computer assisted telephone interviewing (CATI) and computer assisted web interviewing (CAWI). Sampling followed a proportionate, stratified by region, systematic procedure to ensure a nationally representative sample of the urban/rural population. Data were collected using a structured questionnaire consisting of four parts: 1) demographics; 2) knowledge about COVID-19; 3) attitudes toward COVID-19; and 4) practices to control COVID-19 and vaccination against the flu. RESULTS Of the respondents, 66.3% (n=665) had not been vaccinated for seasonal influenza during the 2019-2020 season, the period prior to the COVID-19 pandemic. However, of those, 21.8% showed willingness to receive the vaccine (n=145) the upcoming flu season 2020-2021. Factors independently associated with increased intention to vaccinate in those that had not been vaccinated the previous flu season included: age ≥65 years; the belief that vaccination against the flu is considered preventive against the spread of the coronavirus; not believing that coronavirus was man-made in a laboratory; and not believing that the pandemic will end once a large percentage of the population is infected. CONCLUSIONS Factors that shift public opinion in favor of seasonal flu vaccination can be utilized to design effective strategies to increase vaccination uptake.