Survey Design and Population
We designed a cross-sectional, age-stratified SARS-CoV-2
seroepidemiological survey in community-based sites across 10 regional
capitals of Cameroon, in line with the World Health Organization (WHO)
UNITY studies framework.13, This survey took place
from October to December 2020 at 30 purposively selected community-based
sites (three in each regional capital), including marketplaces, bus
stops, and busy commercial intersections. High traffic venues were
chosen because they most likely had a broad representation of age
groups, sexes, and socioeconomic statuses. The sites were selected in
conjunction with local stakeholders [Cameroon Ministry of Health, U.S.
Centers for Disease Control and Prevention (CDC) in Cameroon]. For a
more representative sample of the regional population, we set regional
quotas for three broad age groups: 5-19 years, 20-49 years, and 50+
years (Appendix Table 1). The quotas were proportional to the regional
population based on census data (2020) for each of these age
groups.14
Children < 5 years were excluded due to the difficulty in
obtaining blood from young children, especially in such public settings.
At each site, survey staff used banners and other promotional materials
and loudspeakers to announce the survey and attract attention to the
on-site survey tent. If participants were traveling in groups, only one
adult and one child (5 years and above) per household were eligible to
participate based on self-reported relationships. Data were collected at
each site for approximately three weeks, until quotas were met.
Prior to participation in the survey, written informed consent was
obtained from adults (aged ≥21 years as per Cameroon regulations) and
emancipated minors and from parents for participants aged ≤20 years.
Written informed assent was also obtained from participants aged 10-20
years. The survey was approved by the Cameroon National Research Ethics
Committee and Columbia University reviewed and designated it as public
health surveillance. The study
was reviewed in accordance with the U.S. CDC human research protection
procedures and was determined as research. However the CDC investigators
did not interact with any individuals or have access to identifiable
data or specimens for research purposes.