Details of the SARS-CoV-2 seroprevalence survey supported by the US CDC

In a recent study posted on medRxiv* Preprint server, researchers with data from the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) serum survey supported by the Centers for Disease Control and Prevention (CDC) for low and middle incomes. Review and analyzed (LMI) country.

Background

The seroprevalence survey assesses the prevalence of pathogen-specific antibodies in serum. Therefore, they are used to assess the prevalence of human immunodeficiency virus (HIV), hepatitis B, and type C virus and provide information to public health models for disease management and eradication. ..

SARS-CoV-2 seroprevalence survey data may complement case monitoring data and provide important information for guiding public health strategies. This shows the actual burden of coronavirus disease 2019 (COVID-19), shows local herd immunity, identifies hotspots and risk groups for infection, and may help assess vaccination rates. ..

Only 23% of the seroprevalence surveys conducted in 2020 were from LMI countries. Therefore, other international players, including the CDC and the World Health Organization (WHO), supported seroprevalence studies in LMI countries in mid-2020.

About research

The US CDC supported 72 international serum studies in 35 LMI countries between May 12, 2020 and February 28, 2022. The CDC provided technical assistance (TA) on statistical, epidemiological, methods, and financial assistance (FA) for these serum studies through offices in LMI countries. They also provided training for sampling and techniques, field staff, protocol development, data analysis, interpretation, and dissemination of results. In addition, the CDC encouraged countries to use the WHOUNITY protocol to ensure as much standardization as possible.

The US CDC has established an International Task Force to activate the Emergency Operations Center and handle incident management systems in response to the January 20, 2020 COVID-19 pandemic. This workforce, primarily composed of CDC staff, monitors the role of the CDC in the global response to the implementation and monitoring of SARS-CoV-2 international seroprevalence studies and coronavirus-assisted economic security (CARES). Received funds from the law.

Monthly virtual group calls facilitated communication between CDC headquarters and country office staff engaged in seroprevalence work. The CDC-supported Microsoft Excel-based tracker for international seroprevalence studies helped project staff update the protocol development and implementation status of each study. The author used this data to review and analyze the information in the current paper.

The current review describes all CDC-supported serum studies and their goals and characteristics. The analysis describes the WHO area of ​​the study, the study design and population surveyed, the type of support provided by the CDC, ie TA, FA, or both, the clinical tests used, the conduct of the study, and the dissemination of the results. It is targeted. The researchers also discussed the challenges faced during the study and suggested measures to use serum survey data to inform public health activities.

Survey results

Of the 72 CDC-supported serum studies, 61% received both TA and FA, and 30% and 3% received only TA and FA, respectively. The remaining 6% were part of an informal review.

In terms of target audience, 54% of these surveys targeted the general population within the WHO Africa region, while 13%, 7%, and 7% included sample pregnant women, health care workers, and patients. It was targeted at other specific population segments. Students etc. respectively. The remaining 18% targeted other groups such as truck drivers.

Interestingly, about 55% of studies used enzyme-linked immunosorbent assay (ELISA) to detect SARS-CoV-2 antibodies in serum, but only 11% used it rapidly. antigen test. Researchers evaluated 63% of the survey rounds against the WHO UNITY criteria, but only 79% used methods that adhered to those criteria. The CDC-sponsored research was at various stages of implementation. In particular, it was carried out by the local government that owns the data. However, the CDC may gain limited and temporary access to seroprevalence data for analysis.

Data collection was completed in just 34 serum survey rounds, but only 5 studies (6%) conducted in Africa were published. In published data, estimates of seroprevalence of SARS-CoV-2 ranged from 2.1% in Zambia to 34.7% in Kenya. Similarly, the ratio of infections to reported cases ranged from 21: 1 in Ethiopia to 295: 1 in Senegal.

Conclusion

The support provided by the CDC has strengthened the regional capacity to conduct SARS-CoV-2 epidemiological surveillance in some LMI countries. However, challenges in conducting studies and interpreting seroprevalence results are constantly evolving.

Therefore, it is possible to identify and predict epidemic patterns over time, solve long-term problems with SARS-CoV-2 protection correlation (CoP), and integrate COVID-19 serum monitoring with monitoring of other pathogens. It was important. Plasmodium malaria Species, dengue virus, and other humans coronavirus.. In particular, the cross-reactivity of antigens between SARS-CoV-2 and these pathogens yields false positive results on SARS-CoV-2 serological tests. To address this, the CDC recommended conducting an independent national verification of the results, especially in the WHO Africa region.

The introduction of the COVID-19 vaccine also challenged the design and implementation of SARS-CoV-2 serum studies and the interpretation of their results. For example, the SARS-CoV-2 serum study design failed to identify potentially at-risk populations and efficiently allocate vaccines in countries that could not distinguish between innate and vaccine-induced immunity. Similarly, the phenomenon of weakened immunity hampered the assessment of both the actual burden of COVID-19 and the vaccination rate.

It is worth noting that the type of antibody assay, the timing of the test, and the severity of the infection affect it. Effectiveness of Serum survey. Therefore, the CDC has introduced a new seroprevalence protocol. They also adapted existing ones to address the epidemiology, laboratory, and other considerations of vaccine introduction. Overall, CDC’s support for international seroprevalence studies has greatly helped guide public health interventions to control the spread of the COVID-19 pandemic at the global level.

*Important Notices

medRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.