South Korea is not adequately communicating the uncertainties of its herd immunity goals to the public, experts said Tuesday, warning that this was likely to damage the credibility of official announcements.

Inoculating 70 percent of the population with their first doses by September and reaching herd immunity by November as proclaimed by the government is “almost physically impossible,” according to Dr. Ma Sang-hyuk, the Korean Vaccine Society’s vice president.

He said in a phone interview with The Korea Herald Tuesday that based on the current pace of the efforts and the vaccine supply timeline, there were “too many variables at play” to affirm herd immunity will happen by the end of fall.

Over the past 10 days, since the mass vaccination campaign kicked off on Feb. 26, more than 383,000 people in Korea have received the first shot in a two-dose series. This translates to about 39,000 doses being administered per day.

“If you do the math, in order to vaccinate roughly 36 million people (70 percent of Korea’s 51 million population), we have to be administering some 300,000 doses each day between now and October -- considering that the vaccines, with the exception of Janssen, require two doses,” he said, adding this was a very rough calculation.

“You also have to factor in things like how Pfizer and Moderna vaccines can only be given at certain institutions equipped with the technology and training. Vaccination facilities may suffer temporary closures, with their staff quarantined, following visits by infected persons.”

Still, the pace could pick up considerably once more vaccination sites are set up, he said. The government has said it plans to operate around 10,000 vaccination centers as more vaccines reach Korea.

Aside from the 1.5 million doses of the AstraZeneca’s vaccine and the COVAX-distributed 117,000 doses of Pfizer’s that were supplied in the last week of February, the amount of vaccines confirmed as arriving before July are 1.05 million doses of AstraZeneca vaccine and 3.5 million doses of Pfizer vaccine, according to Prime Minister Chung Sye-kyun.

This was not sufficient to cover the target populations, Ma said. He also pointed out the prime minister had a history of painting a rosier outlook. Chung had told government meetings and press briefings that vaccinations in Korea would begin in early February before they were delayed, he said.

“It’s unclear at this point if the vaccines will be delivered in time to carry out the vaccination campaign as planned. We don’t know whether 70 percent is indeed the herd immunity threshold. We may never even reach herd immunity,” he said.

“The government is failing to communicate these uncertainties clearly. Those in positions of authority need to be more upfront (about the uncertainties), or else it’s going to be like the boy who cried wolf,” he said.

“The problem with such public communication is that it may send a wrong message that the virus will be vanquished come fall, when the fight may well drag on into next year,” he said.

“Many people will look to November as a point for the virus to be gone and for life to return to normal. How will they explain when people realize life won’t be returning to normal months later?”

To sustain public trust in the long run, the government should be avoiding ambiguities, he said. “Public compliance is crucial to successful vaccination campaign.”

November herd immunity “seems aspirational,” agreed virologist Dr. Paik Soon-young of the Catholic University of Korea. “I think it should be understood as the government’s commitment to get to vaccinations as fast as possible.”

As recently as March 2, President Moon Jae-in said in a Cabinet meeting that his administration “will be ready to take on any challenge that may arise” so that “there will be herd immunity by November without fail.”

Paik said as most of the scheduled vaccine supplies are concentrated in the third quarter, a lot depended on Korea’s ability to efficiently execute mass vaccinations for the general public then. It is estimated to take until July or August to get through the priority groups.

More contagious variants may render the journey to the goal more treacherous, he said, particularly the variant discovered in South Africa.

The Korea Disease Control and Prevention Agency on Monday confirmed a first community transmission of the South Africa variant, which is less responsive to the current vaccines. The agency has to date detected 182 variant cases in Korea.

But the vaccines are still the most vital tool against the virus, Paik said, and they are expected to provide at least some protection against the variants.

Paik called for planning in advance to bring in updated vaccines to defend against the new variants, and expand vaccine eligibility as people aged 65 or older are not being vaccinated right now per the local regulator decision that ruled out AstraZeneca vaccine for the age group.

“Instead of herd immunity, perhaps we should be discussing how to make vaccine more accessible to the wider public, and how to sustain public willingness to socially distance as the pandemic prolongs.”

By Kim Arin (arin@heraldcorp.com)