"Rare Blood Clots Very Uncommon"... AZ Vaccine Resumption, Under 30 Excluded (Comprehensive)

"Rare Thrombosis Incidence Only 1.3 per Million in Korea"
However, Vaccination Risk Exceeds Benefit for Those Under 30
Plan to Adjust Vaccine Recipients and Supplement Q2 Strategy

[Asia Economy Reporter Kim Ji-hee] The administration of the AstraZeneca (AZ) vaccine, which had been suspended due to controversy over blood clot formation, will resume from the 12th. However, considering the analysis results from the European Medicines Agency (EMA) and others, those under 30 years old will be excluded from the AZ vaccine recipients.

Jung Eun-kyung, head of the COVID-19 Vaccination Response Promotion Team, stated at a briefing on the 11th, "We will resume the vaccination with the AZ vaccine, which was temporarily postponed and put on hold on the 8th, starting tomorrow according to the second quarter vaccination schedule." Accordingly, vaccinations will begin for special education, childcare for disabled children, and infection-vulnerable facilities, whose vaccination start dates were postponed on the 7th, and vaccinations will also resume for those under 60 years old in nursing hospitals, nursing facilities, and medical institutions at the hospital level or higher.

However, those under 30 years old are excluded from the AZ vaccine recipients. It was judged that for those under 30, the benefits of vaccination do not outweigh the risks of rare thrombosis that may be induced by the vaccine. The UK also recommends other vaccines for those under 30 without underlying diseases based on similar analyses.

On the afternoon of the 15th, medical staff demonstrated the preparation of the AstraZeneca (AZ) vaccine at the COVID-19 vaccination center set up in the auditorium of Seongdong-gu Office in Seoul. Photo by Moon Honam munonam@

Vaccination Expert Committee: "Domestic COVID-19 risk continues... For those under 30, vaccination risk > benefit"

The Promotion Team held expert consultations and the Vaccination Expert Committee from the 8th to review domestic and international trends including EMA announcements and prepared this AZ vaccine vaccination plan. Previously, the EMA, the UK Medicines and Healthcare products Regulatory Agency, and vaccine advisory bodies recognized on the 7th that rare thrombosis cases are possible adverse reactions to the AZ vaccine based on additional analysis results. Accordingly, the Promotion Team and domestic thrombosis and vaccine experts referred to UK cases and derived vaccination plans through risk-benefit analysis by age and group.

Choi Eun-hwa, chairperson of the Vaccination Expert Committee, explained, "Most of the thrombosis cases reported after AZ vaccination in Europe are very rare specific thromboses accompanied by low platelet counts and some bleeding, such as cerebral venous sinus thrombosis and visceral venous thrombosis, which occur very rarely in Korea." She added, "According to domestic adverse reaction surveillance results, three cases of thrombosis after vaccination were reported, one of which was recognized as causally related to the vaccine, but it did not meet the case definition set by the EMA."

Accordingly, the committee maintained the position that the benefits of AZ vaccination outweigh the risks of very rare specific thrombosis occurring after vaccination. However, "Rare thrombosis tends to occur more frequently in younger ages, whereas the risk of severe infection and death from COVID-19 increases significantly with age," and "Analyzing benefits and risks by age, vaccination is recommended for those 30 and older, but not recommended for those under 30, where the benefit-risk ratio is not high," the committee stated.

Professor Jung Jae-hoon of Gachon University Department of Preventive Medicine said, "The domestic epidemic situation is better than overseas but is gradually increasing," and "The incidence of rare thrombosis caused by the vaccine is estimated at about 1.3 per million people in Korea, but according to EMA announcements, it is about 6.5 per million, roughly five times higher than in Korea." According to six scenarios derived by Professor Jung considering various variables, even the most conservative prediction showed that for those aged 50 and above, the benefits of vaccination overwhelmingly outweigh potential harms.

Professor Jung added, "For those aged 30 to 49, it is difficult to evaluate the harms and benefits of vaccination. However, this result was evaluated for the general public, and the second quarter vaccination targets are not exactly the general public but those with higher exposure risk to COVID-19 or those who need to protect patients, so the evaluation might differ slightly. Also, the domestic vaccine supply situation was somewhat considered."

Professor Na Sang-hoon of Seoul National University College of Medicine's Department of Cardiology also said, "According to the EMA final report, cases of rare thrombosis with strong association and accompanied by thrombocytopenia in specific venous sites must be distinguished, and no such case has yet occurred in Korea," adding, "For cerebral venous sinus thrombosis without thrombocytopenia, the incidence in Korea is about one-fifth that of Western countries."

On the morning of the 26th, Shin Jeong-sook, a caregiver at an elderly care center, is answering questions from reporters after receiving the first dose of the AstraZeneca (AZ) COVID-19 vaccine at the Geumcheon-gu Public Health Center in Seoul. Photo by Joint Press Corps

Who will receive the doses excluded from those under 30?

With those under 30 excluded from vaccination, some adjustments to the vaccination plan have become inevitable. Among the AZ vaccine recipients planned for the second quarter, the largest age group is 65 to 74 years old, approximately 4.97 million people. Those under 65 eligible for the AZ vaccine number about 2.38 million, and among them, those under 30 excluded this time are estimated to be about 640,000, roughly 27%. Most are workers in infection-vulnerable facilities, caregivers for the disabled and elderly, flight attendants, teachers, and essential social workers.

Jung Eun-kyung, director of the Korea Disease Control and Prevention Agency, said, "We will continue monitoring safety and effectiveness for the current targets and revise and supplement vaccination plans for vaccines other than AZ. We will also revise the second quarter vaccination plan to adjust the AZ vaccine doses originally planned for those under 30 to other recipients and inform accordingly."

She added, "We judged that vaccination for those aged 65 to 74 is much more urgently needed than for other age groups, and since a large quantity of AZ vaccine will arrive in May and June, we plan to vaccinate through entrusted medical institutions starting in May. We will continue to improve vaccine supply management and vaccination plans to possibly advance the schedule."

To prepare for possible vaccination refusal due to the exclusion of those under 30, the authorities plan to strengthen the response system. They will establish a surveillance system for early detection and treatment of rare thrombosis and enhance diagnostic and treatment capabilities through case sharing with related academic societies such as the Thrombosis Society and Neuroscience Society. Since thrombosis can prevent severe worsening and death if detected and treated early, the Promotion Team plans to supplement the vaccination guide for vaccine recipients so that those vaccinated can recognize adverse reactions early and seek medical care promptly.

Those who have already completed the first dose will proceed with the second dose as scheduled regardless of age. Among AZ vaccine first-dose recipients, those without rare thrombosis-related side effects will receive the second dose with the same vaccine. Currently, about 910,000 people have received the first AZ dose, of which approximately 135,000 are estimated to be under 30.

The authorities stated, "The committee and expert review opinions are that if rare thrombosis occurs after the first dose, the second dose is not recommended." They added, "Cross-vaccination is not recommended yet due to lack of evidence. As more medical evidence is established, vaccination criteria will continue to be updated."

[Image source=Yonhap News]

First Quarter Vaccine Effectiveness... AZ 85.9%, Pfizer 91.7%

Meanwhile, among about 760,000 people vaccinated against COVID-19 in Korea as of the 8th, 83 cases of infection were confirmed. About half of these infections occurred after the 14-day antibody formation period following vaccination.

According to the first quarter vaccine effectiveness announced by the Central Disease Control Headquarters on this day, among 767,253 people who completed one dose by the 8th, 83 were infected with COVID-19. The incidence rate was 10.9 per 100,000 vaccinated. Among 706,635 who received the AZ vaccine, 79 were infected, recording 11.2 per 100,000, and among 60,618 Pfizer vaccine recipients, 4 were infected, 6.6 per 100,000.

There were 40 cases (6.2 per 100,000 vaccinated) confirmed 14 days after AZ vaccination, while no cases were confirmed in the Pfizer group during the same period.

Among 137,374 unvaccinated individuals eligible for vaccination in the first quarter, 109 were confirmed infected with COVID-19. The incidence rate was 79.3 per 100,000, significantly higher than among vaccinated individuals.

Accordingly, the overall vaccine effectiveness among the first quarter vaccination targets since February 26 was 85.9% for AZ and 91.7% for Pfizer. Vaccine effectiveness confirmed 14 days after one dose was 92.2% for AZ and 100% for Pfizer.

However, the authorities explained that these results should be interpreted cautiously as they do not adjust for differences in observation periods after vaccination among subjects.