Response Rates in a COVID-19 Seroepidemiological Survey in Nigeria: Variations by State, Age Group, and Urban-Rural Settings

The COVID-19 pandemic has presented substantial global challenges, necessitating a deep understanding of infection dynamics across diverse populations. Seroepidemiological studies offer valuable insights into these dynamics but depend heavily on obtaining representative samples. This study aimed to assess participant response rates across different age groups and residence settings in Nigeria, focusing on three distinct locations: Lagos, Delta, and Sokoto States. The study utilized a probability sampling procedure, employing a two-stage cluster sampling method to select Enumeration Areas (EAs) and then households with equal probability. Data from the sero-epidemiological survey served as secondary data for analyzing response rates. The American Association for Public Opinion Research (AAPOR) Response Rate 4 (RR4) method was applied. Response rates were calculated, and analyses stratified by age and residence were conducted to examine survey response patterns. In Lagos State, response rates varied significantly across age groups and residence settings. Children aged <2 years had a response rate of 87.9%, but a lower survey response rate of 54.3%. The 2-9 years age group had a high response rate of 97.4% with a survey response rate of 75.5%. Adolescents (10-17 years) showed a response rate of 99.3% and a survey response rate of 83.5%. Adults aged 18-64 years had a response rate of 99.2% and a survey response rate of 86.8%. The 65+ years age group showed a response rate of 96.3% and a survey response rate of 85.9%. Urban areas had a higher response rate (99.1%) compared to rural areas (95.2%), with corresponding survey response rates of 85.5% and 73.1%, respectively. Sokoto State presented lower response rates, particularly among children aged <2 years (4.3%) and the elderly (65+ years) at 19.8%. Urban areas in Sokoto had significant challenges, with an overall response rate of 35.9% and a survey response rate of 4.1%. In contrast, Delta State showed more consistent results, with response rates of 93.2% overall and a survey response rate of 81.8%. The study highlights variations in response and survey response rates across different age groups and residence settings in Lagos, Delta and Sokoto States. These findings underscore the importance of considering demographic and geographic factors when interpreting seroepidemiological data.