COVID-19 monitoring did not track mild or asymptomatic infections at the start of the pandemic. We needed to find a way to gather information on the spread of COVID-19 without solely focusing on severe cases.
We discussed using donor samples to track immunity to the COVID-19 virus in the Welsh population with Public Health Wales. We can do this through measuring antibody levels in the blood.
Recognising testing support was needed, Swansea Bay University Health Board and Cwm Taf Morgannwg University Health Board were introduced to conduct antibody testing required for the serosurveillance.
We use samples that would otherwise be wasted for this project. Samples came from donors across the country, which helped estimate immunity levels in different parts of Wales.
By the end of 2020, we had set up a scientifically robust way to estimate immunity from the samples.
Another test was added later in 2021 to measure antibodies from vaccination, allowing us to track immunity and see how vaccines protect the population.
We can also relate some of the blood samples tested to the same donors who regularly donate throughout the year, allowing us to see changes in immunity over time and estimate how long immunity lasted.
Our project provides month-on-month estimates of the number of people with antibodies to the COVID-19 virus. From this, health bodies and Welsh Government can decide on vaccination plans and safety measures.