According to recent data from World Health Organization (WHO), over 4.98 billion COVID-19 vaccine doses in 183 countries have been administered worldwide.
While infection with the COVID-19 virus typically provides natural immunity, which means the body creates antibodies after infection with the virus, vaccine-derived immunity refers to antibodies created after receiving the vaccine.
A positive antibody test indicates that the person has likely been infected with COVID-19 at some time in the past or can be used to evaluate the immune response following vaccination. Specifically, an antibody test examines the presence of antibodies in the blood of tested individuals, demonstrating an immune response to the infection.
Antibody tests are essential for detecting previous infections in people who had few or no symptoms of COVID-19, and determining the level of immunity across different communities, or in the workplace. So far, antibody tests have played a key role in tracking the number of COVID-19 infections and evaluating the progress of the pandemic.
To date, several large-scale studies have been carried out to evaluate trends in COVID-19 infection levels and immunity across several populations. For instance, the REACT (Real Time Assessment of Community Transmission) study conducted in the UK in 2020 in both healthcare workers and the general population. This nation-wide antibody surveillance study involved self-testing at home helped researchers evaluate trends in infection across the country and develop more accurate antibody tests. The REACT study was commissioned by the Department of Health and Social Care, and was conducted in partnership with Imperial College London, Imperial College Healthcare NHS Trust and Ipsos MORI.
“The thorough and rigorous work carried out by Imperial College London has allowed us to find a robust at home finger prick test for COVID-19 antibodies. This is the springboard for developing a far greater understanding of COVID-19 antibodies and how prevalent they are in the population through our large-scale antibody study, conducted with over 100,000 members of the public,” said Kelly Beaver, Managing Director – Public Affairs, Ipsos MORI.
Taken together, the results of such studies have shown that monitoring COVID-19 antibody levels across various populations can help scientists to determine the level of risk of COVID-19 infections and prevent their spread. Importantly, this research helps scientists to determine the level of protection antibodies provide following vaccination and/or infection, as well as how long immunity can last.
The sensitivity and specificity of antibody tests are factors that are crucial to their performance, since more accurate antibody tests provide the most reliable results. COVID-19 antibody tests have helped researchers and healthcare professionals to understand the spreading of the virus in specific settings. In addition, they have played a key role in helping individuals decide when it is safe to return to work, travel, and socialize without the risk of transmitting the infection to others or becoming infected.