The proportion of the population who have had COVID-19 or have been exposed to COVID-19 is unknown and remains challenging to assess. Social distancing measures and new ways of working means that new methods of blood sample collection are urgently needed for studies, including the need for remote testing. Whilst several studies are using venous blood draws for antibody testing, there is a need for a validation of alternative methods including the dried blood spot (DBS) method. A validated DBS method for measuring COVID-19 antibodies could make tests more widely available, be more acceptable to patients and study participants, and place fewer demands on the healthcare system because the method requires less blood and samples could be taken remotely.

We are running a large-scale surveillance study in the MRC Fenland cohort to determine the prevalence of antibodies against COVID-19 with repeated measures over a 6-12 month period to ascertain changes in infection during the study period. We are using a novel OneDraw device  from Drawbridge Health for remote DBS sample acquisition from participants in a standardised manner. The advantages of the device are the ability for participants to provide a sample without needing to visit a clinical setting or be visited at home by a healthcare professional, in a minimally invasive, minimal blood volume, and less painful way, which is likely to translate to better compliance with the sampling. This makes it a desirable choice for use in a population-based study with repeated blood collection measures.

There is now a need for a validation study to determine the agreement of COVID-19 IgG antibody measurements using two DBS blood collection methods (OneDraw and a standard finger-prick) with a standard venous sample in a population of COVID-19 antibody negative participants and COVID-19 antibody positive participants. The results of this study will inform the use of the OneDraw device and a DBS COVID-19 antibody test in the Fenland cohort and other populations. It will also inform the use of a traditional finger-prick dried blood spot method for COVID-19 antibody measurement for situations where the OneDraw device is not suitable.

The objectives of this study are therefore to determine whether the DBS sample collected either by a finger-prick or by the novel OneDraw device, provides the same COVID-19 antibody test result as a venous blood sample in a population who have previously been tested for COVID-19 antibodies and tested negative or positive.

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