People who are fully vaccinated against COVID-19 generally do not get seriously ill even if they get infected with SARS-CoV-2. However, they can still transmit the virus to others.
Associate Professor Raymond Lin, director of the National Centre for Infectious Diseases National Public Health Laboratory in Singapore, told The Straits Times that this was the centre’s observation from studying the serology test results of those diagnosed with COVID-19.
In some cases, serology tests help scientists and clinicians determine whether the antibodies were produced by natural infection or through vaccination. Knowing this can help public health officials identify “vaccine breakthrough” cases—or those who get COVID-19 even after being fully vaccinated against it.
Said Prof Lin: “Defining vaccine breakthroughs will help us study how often (such cases) occur, whether they can transmit infection, whether they develop severe disease and whether new variants infect vaccinated subjects more easily.”
He added: “So far, we observe that some infected but vaccinated subjects may transmit the virus to others.”