Unity studies
Serology and Early Investigation protocols
Serologic tests measure the antibody response in an individual. Antibodies to COVID-19 are produced over days to weeks after infection with the virus. The presence of antibodies indicates that a person was infected with the COVID-19 virus, irrespective of whether the individual had severe or mild disease, or even asymptomatic infection. Surveillance of antibody seropositivity in a population can allow inferences to be made about the extent of infection and about the cumulative incidence of infection in the population. The use of serology in epidemiology and public health research enables understanding of:
- the occurrence of infection among different populations;
- how many people have mild or asymptomatic infection, and who may not have been identified by routine disease surveillance;
- the proportion of fatal infections among those infected;
- the proportion of the population who may be protected against infection in the future
In the context of COVID-19, WHO provides a global platform on serology for public health research, detailed below.
Unity studies is a global sero-epidemiological standardization initiative, which aims at increasing the evidence-based knowledge for action.
It enables any countries, in any resource setting, to gather rapidly robust data on key epidemiological parameters to understand, respond and control the COVID-19 pandemic. The Unity standard framework is an invaluable tool for research equity. It promotes the use of standardized study designs and laboratory assays.
Laboratory group
Since 24 February 2020, WHO has been providing molecular testing kits for COVID-19 directly to countries, increasing the capacity of Member States to detect cases or clusters. Molecular testing (RT-PCR) measures acute infection, often in patients with severe disease, as these are the individuals who seek and require health care. This may miss the fraction of mild or asymptomatic infections that do not require medical attention, and as such, the full spectrum of the disease is not known.
Serology can be used to accompany COVID-19 surveillance to measure the extent of infection in the population. However, uncertainty currently remains as to the performance of serologic tests in terms of sensitivity and specificity, and their ability to assess cross-reactivity with other coronaviruses such as common human coronaviruses, as well as SARS-CoV and MERS-CoV.
The laboratory group at WHO, in collaboration with external laboratory partners and FIND, works to evaluate and validate available serologic assays for COVID-19. There are currently several hundred immunoassays marketed for COVID-19 including enzyme-linked immunosorbent assays (ELISA), rapid immunodiagnostic tests (RDT) and high throughput automated platforms. The first validation data on ELISAs and RDTs have been published, but the results are based on limited datasets and not all have been conducted with well characterized samples from COVID-19 patients. Laboratories have also developed neutralization tests which require biosafety level 3 facilities.
Solidarity II
Solidarity II is a global collaboration of public health agencies and academic institutions led by WHO to understand serology for public health in the context of COVID-19. It provides a collaborative work space and global research database for the sharing of scientific protocols, training materials, scientific publications, survey findings, and other information for collaborators.
Solidarity II facilitates the sharing of well characterized panels of sera to enable standardization of serologic assays worldwide, and access to high-quality antigen specifically for assays to conduct serologic surveys. Solidarity II is also working towards the development of a standardized serology assay for collaborators who wish to use a global standard assay and methodologies for laboratories around the world to develop their own serologic assays. It facilitates the sharing of laboratory protocols for serologic assays for the purposes of serology surveys and study protocols, such as the Unity studies (see below). It provides support with analysis of individual serologic surveys and is working towards a meta-analysis of findings across surveys from collaborators to provide a global understanding of seroprevalence and seroincidence of SARS-CoV-2 infection, and the potential impact of different control measures.
Finally, Solidarity II provides a global research database and collaborative work space for the sharing of scientific protocols, training materials, scientific publications, survey findings, and other information for Solidarity II Collaborators.
To join the Solidarity II Collaboration and work together on this shared global challenge, please email [email protected]