Controversy rises over booster shot for Janssen vaccine

A man receives a Janssen coronavirus vaccine at a medical clinic in South Gyeongsang Province, June 10. Yonhap

By Lee Hyo-jin

Controversy is rising over the administration of booster shots for recipients of Johnson & Johnson's Janssen COVID-19 vaccine, as they have reported the largest number of breakthrough infections among fully vaccinated people.

While some medical experts believe the government should immediately offer additional shots to the group, others advise that the plan should undergo a more prudent review.

President Moon Jae-in ordered the health authorities Monday to swiftly come up with a plan to administer booster shots for people who received the single-dose regimen Janssen vaccine, as a recent study in the U.S. suggested that its protection drastically weakens after five months.

According to the study which examined the vaccine's efficacy among 620,000 discharged service members in the U.S., the prevention rate plunged to 3 percent in August, from 88 percent in March.

On Oct. 15, the U.S. Food and Drug Administration's (FDA) expert panel recommended a booster dose of the Janssen vaccine around two months after the first dose.

In Korea, among the 33.18 million fully vaccinated people, 1.46 million, or about 4 percent of the total, have received a Janssen shot, according to the Korea Disease Control and Prevention Agency (KDCA). It was administered mostly to military-related personnel aged over 30 in June.

The country has reported 13,860 breakthrough infections as of Oct. 3. By vaccine type, people who received the Janssen shots made up the largest portion ― 216.1 out of 100,000 had breakthrough infections, followed by 67.9 people receiving AstraZeneca, 43.2 people receiving Pfizer, and 4.9 people receiving Moderna.

The KDCA said it will come up with a plan to provide additional shots earlier than initially scheduled for December.

Vials are seen in front of a displayed Johnson & Johnson logo in this illustration taken Oct. 31, 2020. Reuters-Yonhap

"We are currently analyzing breakthrough infection cases and the protection rate of the Janssen vaccine. We will make the final decision on the booster shot plan next week," said KDCA chief Jeong Eun-kyeong during a briefing, Monday.

The health authorities are currently offering booster shots to frontline medical workers as six months have passed since they received their last dose of the Pfizer vaccine. From Oct. 25, additional doses will be available to the elderly population aged over 60, along with medical workers at nursing homes.

Given this situation, recipients of the Janssen shots are likely to be added to the list of ongoing booster shot vaccinations.

But medical experts are divided on whether the booster shots should be administered immediately, and which vaccine should be given as the second dose.

Chon Eun-mi, a respiratory disease specialist at Ewha Womans University Mokdong Hospital said, "As the Janssen vaccine's efficacy begins to fall two months after the inoculation, they must receive an additional shot within that period. As most Janssen recipients were inoculated in June, the booster shots should be administered by the end of this year.

"It is likely that they will receive an mRNA vaccine ― Moderna or Pfizer ― as a second dose, but it would be better to give them a choice between an mRNA one or Janssen," she added.

But some experts said otherwise. Jung Ki-seok, a professor of pulmonary vascular disease at Hallym University Medical Center, said, "The government should consider offering booster shots depending on the amount of remaining doses."

He added that the government should carefully set up the booster shot plan, saying, "Vaccination plans should be devised based on scientific data, rather than urgency."

Lee Hyo-jin

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