As the number of breakthrough infections amounts to several hundred among people who received Covid-19 vaccines, the government is considering giving booster shots to vulnerable groups.

Rep. Shin Hyun-young of the ruling Democratic Party, a doctor-turned-lawmaker, said that a total of 1,132 breakthrough infections had been reported in the country, with people in their 30s reporting the highest rate of breakthrough infections. They were followed by those in their 40s, 50s, under 30s, 60s, 80s or older, and 70s.

Of the total, 584 received the Johnson & Johnson vaccine, followed by Pfizer’s 284, AstraZeneca’s 254, and 10 people who took cross-vaccinations.

"It is difficult to specify people vulnerable to breakthrough infections as we lack immunoassay data, including neutralizing antibodies at the time of infection," Rep. Shin said. "The government's response is likely to play a significant role in selecting the target of vaccination, inoculation interval and time, and additional vaccine types in preparing for the third shots to prevent breakthrough infections."

Some countries, including the U.S., the U.K., France, have already begun giving booster shots to at-risk people, and Germany has also formalized the implementation of the booster shot. The U.K. plans to provide booster shots from September. France and Germany will start it in autumn for high-risk groups, including those vaccinated with AstraZeneca and Janssen vaccines.

In the U.S., for example, the San Francisco Department of Public Health (SFDPH) said that it would allow people who received the Janssen vaccine to take extra mRNA vaccine under doctoral consultation after deciding to implement a booster shot for the Janssen vaccine recipients.

However, SFDPH clarified that the decision was limited to simply accepting an additional mRNA dose request, not a recommendation or policy change.

SFDPH Deputy Director Naveena Bobba said, "The city is not recommending but rather accommodating special requests, contingent on a doctor's recommendation."

The Joe Biden administration has provided the Janssen for Korean military troops. The Korean government gave the vaccine to reserve forces and civil defense members, mostly in their 30s. A total of 1,129,767 people so far. Considering that Janssen vaccine recipients are relatively active workers, they might become the victims of breakthrough infections, epidemiological experts said.

While announcing its vaccination plan for August, the government also said it would review the booster shot after October and November when the nation achieves a 70 percent vaccination rate, which the officials describe as the turning point for forming herd immunity.

"We are in the process of collecting evidence for the booster shot and reviewing it with our advisors," a Korea Disease Control and Prevention Agency official said.

"There are countries that have begun implementing booster shots for high-risk groups. However, we have not decided on anything about booster shots yet as we are still collecting studies on cases of other countries and types of vaccines needed for the actual supplemental vaccination."

The health authorities explained that the details about subjects and vaccines for booster shots would likely be determined when the nation accumulates adequate evidence.

Meanwhile, the head of the World Health Organization recently called for a moratorium on administering booster shots of Covid-19 vaccines to help ensure that doses are available in countries where few people have received their first shots.

“WHO is calling for a moratorium on boosters until at least the end of September to enable at least 10 percent of the population of every country to be vaccinated,” WHO Director-General Tedros Adhanom Ghebreyesus told a news conference. “No one is safe until everyone is safe because the longer and more widely the coronavirus circulates, the greater the chance that new variants could emerge — and prolong a global crisis in fighting the pandemic.”