Cluster sampling methodology to evaluate immunization coverage

Immunization is a key component of primary health care and an indisputable human right. Vaccines are critical to the prevention and control of infectious disease outbreaks. The coronavirus disease 2019 (COVID-19) pandemic and associated disruptions over the past two years have strained the health systems, with many children missing out on essential childhood vaccines.

To evaluate the immunization coverage among 12-23-month-old children in the rural areas of Community Health Centre (CHC) Dighal and to determine the factors influencing the existing immunization coverage.

A coverage evaluation survey was conducted according to the 30-cluster sampling technique, which is the standard methodology for such surveys devised by World Health Organization. A total of 300 children aged 12-23 months were included, whose immunization details were noted from their immunization cards.

Full immunization rate was noted in 86.7% of the children, with partial and non-immunized children accounting for 9% and 4.3% respectively. The full immunization dropout rate was 4.2%. The common reasons for partial or non-immunization were family problem including illness of mother, vaccine not being available and child being ill. Place of birth (P = 0.014) and availability of immunization card (P < 0.001) were significant predictors of the immunization status. Since the study was conducted in 2020/2021, health services were disrupted due to the COVID-19 lockdown.

Due to the coverage being higher than the national average, it was concluded that the immunization coverage was optimal and not affected by the COVID-19 pandemic.