In the 21st century, the rate at which cases of a disease can spread across the world is unprecedented, as highlighted by the 2019-2020 COVID-19 (SARS-CoV-2) pandemic, with daily confirmed cases in the UK rising exponentially (12 confirmed on the 1st March 2020, and 3,634 on the 7th April, Public Health England). This rapid growth exemplifies the urgent and increasing need for rapid development of readily available, high performing diagnostic tools, to support global efforts in controlling the pandemic.
As stated by the World Health Organization (COVID-19 Situation report 63), diagnostic testing for COVID-19 is critical to track the virus, understand epidemiology, inform case management and to suppress transmission. With COVID-19 symptoms not easily distinguishable from the common cold and flu, population screening paired with conclusive diagnostic testing is one of the most effective methods to control the spread of infection, enabling earlier quarantine and treatment. However, for this to be effective diagnostics developers must evaluate and manufacture tests as quickly as the virus emerges, and be able to quickly adapt to changes in the outbreak. In addition, the global spread of COVID-19 has increased the geographical area where laboratory testing needs to be implemented, with intensified viral molecular testing leading to shortages of testing reagents globally for COVID-19, and for other molecular diagnostics. This further highlights the need for alternative reagents with quicker development times (WHO, Laboratory testing strategy recommendations for COVID-19, 22nd March 2020).
Currently, to ensure the necessary level of accuracy and reliability of COVID-19 diagnosis, testing depends on access to specialised laboratory equipment and trained healthcare professionals, for example in a hospital environment. However, generally it is in these settings where the most vulnerable members of the public are at risk of infection. On 11th–12th February 2020, global leading health experts met at the WHO headquarters to identify research priorities for COVID-19 to control the pandemic, with the first of the eight immediate needs agreed to be to “mobilise research on rapid point of care diagnostics for use at the community level.” (2019 Novel Coronavirus Global Research and Innovation Forum: Towards A Research Roadmap, WHO). Point-of-care (POC) testing does not require specialised laboratory equipment or skills, and gives a fast read-out, similar to a home pregnancy test. This technology offers a solution for effective mass-monitoring and disease management by enabling rapid detection of the virus away from other susceptible individuals.
Although antibodies have shown to be effective reagents in this type of immunodiagnostic assay, they have well-documented limitations, including high cost, time to manufacture, and poor specificity against certain targets, with some targets too difficult to generate antibodies for using traditional processes. The timeline of test development and evaluation can therefore be prolonged when relying on the use of antibodies, which in turn restricts the ability of diagnostics companies to respond to outbreaks fast enough.
This is where Avacta’s Affimer® technology can offer a solution as an alternative to antibodies across a wide variety of diagnostic applications. In comparison to antibodies, Affimer proteins are approximately ten times smaller, and can be developed in 12-14 weeks using cost-effective and standardised processes that only require sub-milligram quantities of antigen, compared to months for standard antibody technologies. The proteins can be expressed in very high, but consistent supply to meet demand worldwide, and can easily be formatted for a wide range of applications using a variety of complex samples. Whilst yielding these benefits, Affimer technology also offers highly specific target recognition, without limitation by the immune system, enabling Affimers to be produced against the more difficult targets.
As a vital aspect of effective disease management, it is increasingly important that limitations faced in rapid development of diagnostics, and especially POC diagnostics, are addressed, to enable the most efficient response for patients. Enabling the timely identification and containment of cases is particularly important when supporting efforts against global pandemics such as COVID-19, to prevent the spread and especially to protect the more vulnerable communities that may be less equipped to tackle and recover from the outbreak.