Importance of serology testing in COVID-19 vaccinations

To confirm COVID-19 vaccine efficacy, some countries in ASEAN are carrying out serology testing. But is it necessary? Dr Leong Hoe Nam and Asst Prof Mondej Sookpranee, infectious disease experts, share their views.

Dr Leong Hoe Nam
Infectious Diseases Physician, Rophi Clinic

Asst Prof Mondej Sookpranee
Infectious disease specialist, Medpark Hospital Thailand


There are several types of responses in vaccinated individuals: no response, a rapid decline in antibody levels or a slow decline over time, or persistent levels of antibodies over a long time. This means that 1/3 or half of vaccinated individuals are at risk because of the decline or lack of response. This would be a risk as vaccinated individuals tend to let their guard down and become more lax in following COVID-19 safety measures.

Serological tests that measure the levels of antibodies could help to quantify the risk of an individual getting infected by COVID-19. This could then inform the countries’ effective vaccine distribution strategy. As vaccines are in low supply, countries could prioritise the vaccines to those with low levels of antibodies. Those who shown no response to the first vaccine could then be given another vaccine.

More studies needed to see what is adequate for such serology tests, and the levels of antibodies needed for the different variants of the vaccines. The world would benefit from WHO leadership for a united response – Dr Leong emphasised that the world will march out of this pandemic at the pace of the slowest nation. Coordination across countries to identify the best-performing vaccines and channeling resources to manufacture those in large scale; and coordination in the diagnostics industry to harmonise serology tests, will go a long way in the ongoing COVID-19 war.

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