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COVID-19 Survey Launches in Nigeria

A new study is underway to assess the prevalence of COVID-19 across four states in Nigeria. Ciheb is supporting the Nigeria Centre for Disease Control (NCDC), Nigeria COVID-19 Research Consortium, the National Population Commission of Nigeria, and the National Malaria Elimination Programme in implementing the study in three of the states, with technical support and funding provided by the US Centers for Disease Control and Prevention.

More than 200 Ciheb staff are being deployed across three Nigerian states—Enugu, Nasarawa, and Gombe—to complete this ambitious survey in less than two-months’ time. The teams will survey 2,040 randomly selected dwellings in rural and urban settings of Nigeria, with approximately 10,200 participants of all ages sampled from selected households.

“The survey will give us an idea about how deeply into the population SARS-CoV-2, the virus that causes COVID-19, has penetrated.” explained Ciheb Associate Director Kristen Stafford, PhD, MPH, one of the survey’s principal investigators. The two other principal investigators are Mrs. Elsie Ilori, MSc, Nigeria Centre for Disease Control, and Laura Steinhardt, PhD, MPH, US Centers for Disease Control and Prevention.

To date, COVID-19 surveillance in Nigeria and in other countries has primarily involved patients with detectable symptoms or severe disease. Those with mild or asymptomatic infections who do not require medical attention have generally not been captured by the existing data. The full extent of the disease in the population has thus not been thoroughly assessed.[1] 

“Considering the unknown numbers of persons that are asymptomatic within the population, the survey will provide a clearer knowledge of the burden of COVID-19 in the country, and this in turn will help inform appropriate response decisions by the Government and relevant stakeholders.”
                                                                                                                                                                   —Mrs. Elsie Ilori, Nigeria Centre for Disease Control

In addition to increasing the understanding of the prevalence of COVID-19, the results of the study, called the COVID-19 Household Seroprevalence Survey (CHSS), will inform local response efforts, including the development of strategies to target potential prevention and control interventions to high-risk groups, develop clinical treatment guidelines to mitigate the effects of COVID-19, and strengthen the health system to respond to the pandemic.

A Cross-Sectional Household Survey

Primary data collection on the CHSS will take place through a cross-sectional household survey. Randomly selected households within designated enumeration areas (obtained from the National Population Commission) will be asked to participate in the survey. Upon obtaining informed consent, surveyors will ask the head of household (or an adult member who normally resides there) to list all the members of the household.

Each member of the household, or their caregiver, will be asked to participate in the survey and, if consent is given, will be asked questions about their symptom history, testing, and care-seeking for COVID-19 since March 2020. "Surveying all people in each sampled household will give estimates of seroprevalence among different age groups, which can help better target Nigeria’s COVID-19 response efforts," Dr. Steinhardt said.

The survey will also assess underlying conditions and the extent to which the population is following public health recommendations to mitigate COVID-19 risks. Some of the questions will include whether respondents are shopping regularly at crowded markets, attending religious services, or taking public transportation. These questions will help to identify which behaviors are more closely associated with infection.

A venous blood sample will also be taken for serological testing to measure antibodies to COVID-19. A nasal swab and an oropharyngeal swab will also be collected for molecular testing for SARS-CoV-2 infection. The results will be used to estimate the fraction of asymptomatic, pre-symptomatic, or subclinical infections in the population.

The survey field staff will also conduct malaria rapid testing. The survey will provide insight on whether SARS-CoV-2 and malaria co-infections are occurring and whether malaria can influence SARS-CoV-2 infection.

"We know very little at this point about how malaria infections might influence COVID-19 infections and transmission. Testing for malaria as part of this survey in this highly endemic setting will help shed light on the situation."  
                                                                                                          —Dr. Laura Steinhardt, CDC

If a malaria test is positive, the individual will be treated with one of the first-line artemisinin-based combination therapies recommended by the Nigerian Federal Ministry of Health.

Longitudinal Follow-Up

Longitudinal follow-up will be performed along with the cross-sectional survey in order to assess how intra-household virus transmission occurs. All households that have a member who tests positive and one who tests negative during the household survey will be eligible for longitudinal follow-up at seven-day intervals for up to 28 days or until all negative members have a positive test, whichever comes sooner. The longitudinal follow-up will be started one week after the cross-sectional component.

Rapid Deployment

The team will complete the cross-sectional survey within 30 days. “Because the virus is spreading rapidly, the sampling window must be narrow in order to get an accurate assessment,” explained Dr. Stafford. Along with the longitudinal follow-up component, the entire study will be completed within seven weeks.

Ciheb will rely on the capacity developed during the 2018 Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS) to quickly ramp up for the CHSS. The NAIIS was one of the largest population-based household surveys ever conducted that assessed the prevalence of HIV, viral load suppression, and related health indicators. “Our field teams on the NAIIS have recent experience with survey implementation and household surveys, and we engaged them for the CHSS,” explained Dr. Stafford. “They’ve done this kind of work before. I have a lot of confidence in their ability to execute.”

The Director General of the NCDC, Dr. Chikwe Ihekweazu, announced the launch of the Nigerian seroprevalence study during a Presidential Task Force briefing on COVID-19 in Abuja.  Read more in the Nigerian Premium Times.

The survey teams will be equipped with full protective gear, including masks, shields, gloves, and other necessary equipment. The survey is also prepared to quarantine a team should any one of its members become infected. Should that scenario occur, “buffer teams” stand ready to take their place and resume their work.

Overcoming Challenges

In addition to the need for rapid deployment, the CHSS faces a number of other challenges. These include overcoming the potential stigma associated with COVID-19. Nigeria is no stranger to infectious disease outbreaks, and many communities have experienced field teams responding to a disease outbreak. However, because the CHSS is not a “response” to stop the outbreak, but rather a means to collect data to study the disease, the potential exists that households may be reluctant to participate.

“Our hope is that we can overcome the stigma that people think that we think they’re infected with COVID-19,” explained Dr. Stafford. To overcome this challenge, the CHSS has been reaching out to communities in the three target states to sensitize them to who the field teams are, what they will be doing, and why they are doing it.

Another challenge is the logistical hurdles involved in delivering samples from the field to the Nigerian National Reference Laboratory (NRL) in the capital city of Abuja. The reason for using the NRL is to ensure consistency of testing and help expand the bio-repository of samples at the NRL. The samples delivered to the bio-repository will be sequenced to determine whether mutations have occurred in SARS-CoV-2 and what strain(s) have been circulating in Nigeria.

However, getting the samples to Abuja from the three states of Enugu, Nassarawa, and Gombe, which are in different parts of Nigeria, within a 24-hour window is no small undertaking.

“We have nine vehicles dedicated to sample transport that will basically be running a non-stop relay,” explains Dr. Stafford. “Gombe is definitely the farthest away and is about a nine-hour drive. Each day, one of the three vehicles will get all of the samples and drive them to Abuja. They’ll stay overnight and then drive back to pick up another shipment while there’s another car coming with samples in the other direction.”

Satellite laboratories located in the three-state survey area will process the samples by centrifuging them and placing them in cryovials for stable transport.

A Window on SARS-CoV-2

To date, several SARS-CoV-2 seroprevalence surveys such as the CHSS have been conducted in higher-income countries such as Spain, Switzerland, and parts of the United States. The CHSS is one of two seroprevalence surveys being conducted on the African continent (the other is in Zambia), and additional surveys are being planned.

These surveys are helping better understand how the virus is spreading in populations across the globe. Each opens an important window on how the novel coronavirus and its associated disease have impacted communities and what steps governments can take in developing an effective response.

[1] The first case of COVID-19 was detected in Nigeria on February 27, 2020. Nearly 58,000 cases have since been confirmed as of September 22, 2020 according to the NCDC. Testing for COVID-19 in Nigeria, though initially slow, has increased. A network of molecular laboratories (currently 66) have been activated for COVID-19 testing. Nevertheless, the relatively low rates of testing in the country suggest that infections are likely to be vastly underestimated.




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