Vaccination homophily in ego contact networks during the COVID-19 pandemic.

Vaccine hesitancy is an inevitable risk for societies as it contributes to outbreaks of diseases. Prior research suggests that vaccination decisions of individuals tend to spread within social networks, resulting in a tendency to vaccination homophily. The clustering of individuals resistant to vaccination can substantially make the threshold necessary to achieve herd immunity harder to reach. In this study, we examined the extent of vaccination homophily among social contacts and its association with vaccine uptake during the COVID-19 pandemic in Hungary using a contact diary approach in two cross-sectional surveys. The results indicate strong clustering among both vaccinated and unvaccinated groups. The most powerful predictor of vaccine uptake was the perceived vaccination rate within the egos' social contact network. Vaccination homophily and the role of the interpersonal contact network in vaccine uptake were particularly pronounced in the networks of close relationships, including family, kinship, and strong social ties of the ego. Our findings have important implications for understanding COVID-19 spread dynamics by showing that the strong clustering of unvaccinated individuals posed a great risk in preventing the spread of the disease.

[Secondary prevention of coronary disease--at the turn of the millennium in light of the Hungarian data of the EUROASPIRE I-II. Studies]. / A koszorúér-betegség másodlagos prevenciója. Helyzetkép az ezredfordulón az EUROASPIRE I-II vizsgálat magyar adatainak tükrében.

UNLABELLED: Relevant national societies attribute special importance to the secondary prevention of coronary patients. This is well formulated in their recommendations (9, 11). Actual clinical practice was studied in 1995-1996 by the EUROASPIRE I study. Its Hungarian data were published in 1999 (8). The scope of EUROASPIRE II in 1999-2000 was to study changes occurred in these 5 years. In this paper the authors intend to answer the question whether the clinical practice of secondary prevention of coronary patients showed any changes at the turn of the millennium. Participating centres, the criteria of patient selection and the applied methods were identical in the two studies. Hospital data of 516 patients below the age of 70 were analysed. There was no difference between the two studies neither in the distribution according to gender and age, nor in the number of death. Documentation of the relevant data in the hospital records improved substantially: blood pressure was registered in every patient chart, lipid values in 91%. Information on smoking however is still missing in 1/3 of the patients, while on weight and height in half of them. The response rate at the follow up investigation on was 75%. The prevalence of obesity increased by 60%, that of smoking by 13% since the first investigation 5 years ago. This rate of increase is the largest among the 9 participating centres. The prevalence of hypertension decreased by 24.5% and the proportion of hypertensive patients receiving treatment increased by 7%. In spite of these blood pressure values over 140/90 mmHg were found in 37% of the patients. The mean triglyceride value increased by 53% and the prevalence of severe hypercholesterolaemia by 43%. Lipid lowering drugs are given to 51% of the patients in contrast to 22% 5 years earlier. In spite of this cholesterol values above 5.5 mmol/l were found in 42%. In respect of prophylactic drugs the proportion of patients receiving beta blockers increased from 58 to 84%. INTERPRETATION: The evaluation of complex risk of patients and their long-term care is still deficient. Drug treatment improved quantitatively but not qualitatively. This and the lack of lifestyle-improving medical efforts is reflected by the increase of the proportion of obese and smoking patients and the persistently high prevalence of hypercholesterolaemia and hypertension.