99% of the Population Have COVID Antibodies... Why Are Confirmed Cases Increasing?

Amid the recent continued spread of COVID-19, it has been found that the vast majority of our citizens possess antibodies that prevent COVID-19 infection. However, as time passes, COVID-19 antibodies decrease, making individuals more vulnerable to infection.

The Korea Disease Control and Prevention Agency's National Institute of Health announced on the 9th the results of the third nationwide survey on COVID-19 antibody positivity rates conducted from March 27 to April 15 this year, targeting 9,798 people aged 5 and older in collaboration with the Korean Society of Epidemiology and local community organizations. According to the survey results, the overall antibody positivity rate, combining antibodies from natural infection and vaccination, was 99.2%, a slight increase compared to the first survey in August-September last year (97.6%) and the second survey in December of the same year (98.6%).

The natural infection antibody positivity rate obtained through COVID-19 infection was 78.6%, rising from 57.2% in the first survey and 70% in the second survey. This means that nearly 8 out of 10 citizens have been infected with COVID-19 and still possess antibodies.

The proportion of 'hidden infections'?those who were actually infected but not confirmed due to being asymptomatic or other reasons?is 19.1%, about 1 in 5 people. This is similar to the levels in the first (19.4%) and second (18.5%) surveys.

COVID-19 Spread

The natural infection antibody positivity rate (94.1%) was highest among children aged 5 to 9, who have a low vaccination rate. This rate decreased with increasing age. However, the natural infection antibody positivity rates for those aged 50-64 and 65 and older were 77% and 68.8%, respectively, which is more than a 10% increase compared to the second survey. This is interpreted as an effect of the minimal additional vaccination rates among these groups at the end of last year.

A representative from the Korea Disease Control and Prevention Agency stated, “Our society has confirmed that the overall antibody positivity rate against COVID-19 is high due to continuous vaccination and infections. This is considered one of the factors for the reduced severity and fatality rates following the Omicron wave.”

However, antibody levels decrease over time, so reinfection with COVID-19 is possible. According to the agency, unvaccinated individuals had a 2.02 times higher risk of reinfection compared to those vaccinated with the original monovalent vaccine, and a 3.1 times higher risk compared to those vaccinated with the updated bivalent vaccine.

Additionally, the survey results showed that immunity in the hybrid immunity group, acquired through both COVID-19 infection and vaccination, lasted longer than in groups who were vaccinated only or had natural infection only.

However, as immunity wanes over time in all groups including the hybrid immunity group, the risk of reinfection remains. To prevent severe illness, the agency urged the elderly to be cautious about COVID-19 infection and to participate in additional vaccinations in the second half of the year. The Korea Disease Control and Prevention Agency made this appeal.

This content was produced with the assistance of AI translation services.