Rationale:

There is no information on how intense transmission of COVID-19 happens in Kinshasa, partly
due to a reduced laboratory capacity for polymerase chain reaction (PCR) confirmation of
acute cases, and an aspecific presentation of clinical symptoms. The focus of this COVID-19
seroprevalence study on health care workers and their households, was based on the following
rationale. Health care workers (HCW) are among the groups at higher risk as they are directly
or indirectly exposed to COVID-19 patients. They also form a group of specific interest as
they are in close contact to vulnerable patients at high risk for severe COVID-19. In
addition, their illness or absence from work significantly affects the health system's
ability to respond to the COVID-19 pandemic and retain its other essential functions. HCW are
trained in infection prevention and control (IPC). However, it is likely that at least some
of them will get infected either at their workplace(s) or elsewhere. In particular health
facilities with limited access to personal protective equipment (PPE) and regular water and
sanitation facilities, IPC could even potentially be hampered, resulting in an increased risk
of infection transmission among HCW, from HCW to their patients as well as to their household
members. Because of this crucial role played by HCW in the transmission chain, it is of
utmost importance to assess the proportion of asymptomatic infections among them.

Aim of the study:

This study aims to investigate severe acute respiratory syndrome (SARS-CoV-2) seroprevalence
and seroconversion among HCW in Democratic Republic of Congo (DRC) and their household
members, including asymptomatic ones, in order to generate insights into the transmission
dynamics as well as the clinical presentation of the disease.

Primary objectives

- Determine seroprevalence of SARS-CoV-2 infection among active HCW of hospitals and
primary health care units of Kinshasa at T0;

- Determine seroprevalence of SARS-CoV-2 infection among household members of active HCW
of hospitals and primary health care units of Kinshasa at T0;

- Determine incidence of SARS-CoV-2 seroconversions among HCW of hospitals and primary
health care units of Kinshasa over a 3 months' time period;

- Determine SARS-CoV-2 seroconversion among household members of active HCW of hospitals
and primary health care units of Kinshasa over a three months' time period.

Secondary objectives

- Identify work-related risk factors (infrastructural, availability of equipment and
behavioral) for seroconversion of HCW;

- Identify socio-demographic and behavioral risk factors for seroconversion of household
members;

- Determine the proportion of asymptomatic cases among seroconversions occurred during the
study period among HCW as well as among their household members;

- Assess secondary attack rate among household members of symptomatic and asymptomatic
HCW.

- To compare the performance of an in-house Luminex platform serologic diagnostic test,
commercialized antibody ELISA test and an antibody rapid diagnostic test (RDT) against
the gold standard serological test (neutralization) in tropical settings with intense
cocirculation of malaria and other infectious diseases

Description: 650 HCW and 1000 household members will be surveyed at 4 time moments. At each
moment, a questionnaire is filled exploring the professional and community risk exposure and
the appearance of symptoms compatible with a COVID infection. At the same time, a serum
sample is taken by the HCW and a 'dried blood spot' is done by the household members. These
samples will be analyzed to verify if the participants were exposed to the SARS-CoV2 since
the start of the epidemic. The use of a cohort will allow us to describe how the epidemic
evolves over a 4 to 6 month period in Kinshasa, but will also make it possible to evaluate
how the antibodies are waning or not waning over time.

An amendment is added to the protocol, stating an additional 2 surveys in april/June 2021 and
October/November 2021 to evaluate impact of second wave and of vaccination campaign.