Restoring waning COVID-19 immunity is on track in South Korea.
The country's health authorities have cut the interval between getting fully vaccinated and receiving booster shots from six months to four months, for people aged 60 and above or those in high-risk facilities.
Those in their 50s are now able to get the extra jab FIVE months after full inoculation.
The reason behind the changes? Growing concerns over decreasing antibodies.
"Due to the Delta variant spreading multiple breakthrough cases have been reported from nursing homes and high risk facilities particularly an increase of severely ill cases and deaths among the elderly."
According to health officials 99 out of 100-thousand cases are breakthrough infections mostly in people aged over 60 which has led to cases of severely illness or death.
The question remains: can shortened vaccine interval for booster shots restore vaccine-efficacy to fight against these breakthrough and critically ill cases?
"I think the government did well shortening to 4 months. Of course, this can't solve the recent outbreak right away. As the long winter approaches the fact that around 13 million people will get booster shots at the end of this year means they are now protected safely until early next year."
However, others said that breakthrough infections will keep popping up even after booster shots.
"Breakthrough infections will occur even after getting booster shots. We are hoping to see a reduction in breakthrough infections, but they won't completely disappear. Some people don't have immunity after vaccinations even if they get six booster shots, they will not get enough immunity against breakthrough infections.
And, will the booster shots work against Delta infections?
People in Israel have been getting additional jabs amid the rapid spread of delta variants.
Those given booster shots showed 10 or 20 times more vaccine-efficacy after 12 days.
Elsewhere Hungary and Belgium have begun administering booster shots four months after full vaccination.
The UK government are considering to shortening the vaccine interval from 6 months to 5 months.
However, authorities added that uncertainty remains over whether to give extra booster shots later based on the future situation in terms of the delta spread.
With the following changes, almost 14 million people will be eligible for booster shots by the end of this year.
Choi Won-jong, Arirang News.