[Q&A] Is the 2-valent vaccine effective against BQ and BA.2.75 variants?

"BQ and other BA.5 subvariants
likely to have infection prevention effects"

[Image source=Yonhap News]

[Asia Economy Reporter Kim Young-won] From the 14th, vaccination with Pfizer's bivalent vaccine (updated vaccine) targeting the BA.4/5 variant and the original Wuhan strain of the COVID-19 virus will begin for adults aged 18 and over. In addition to the advance reservations that started on the 27th of last month, same-day on-site vaccinations using leftover vaccines are also available.

When did the winter vaccination start?

The government named the vaccination plan "winter vaccination," shifting from a dose-centered approach such as the 2nd and 3rd doses to a season-centered approach similar to influenza (flu) vaccination. Winter vaccination using the bivalent vaccine first began on the 27th of last month. The initial priority groups for winter vaccination were elderly people aged 60 and over, immunocompromised individuals, and residents and workers of nursing hospitals and facilities. From the 7th, the target was expanded to adults aged 18 and over. The BA.4/5-based bivalent vaccine began to be administered for the first time on this day.

What types of updated vaccines have been introduced domestically?

Currently, Moderna's vaccine targeting Omicron BA.1, Pfizer's BA.1-targeting vaccine, and Pfizer's BA.4/5-targeting vaccine are used for winter vaccination. In Moderna's case, a comparison of immunogenicity using virus-specific neutralizing antibody titers four weeks after additional vaccination showed that the bivalent vaccine group (334 people) had 1.75 times higher neutralizing antibodies against BA.1 and 1.22 times higher against the Wuhan strain compared to the original vaccine group (260 people). For Pfizer's BA.1 bivalent vaccine, a comparison between 178 bivalent vaccine recipients and 163 original vaccine recipients four weeks after additional vaccination showed that the immunogenicity of the bivalent vaccine recipients was 1.56 times higher against the Omicron variant than that of the original vaccine. The BA.4/5-targeting vaccine, which began administration on this day, showed a 2.6-fold increase in neutralizing ability against these variants compared to the original vaccine in preclinical results.

Which vaccine should be taken during winter vaccination?

The health authorities recommend the bivalent vaccine over the original vaccine developed against the Wuhan strain, but they have not set a priority among the three bivalent vaccines. Baek Kyung-ran, Commissioner of the Korea Disease Control and Prevention Agency, said, "The bivalent vaccine targeting the Omicron variant is expected to provide prevention against severe illness and death, as well as some protection against infection from the Omicron variant."

Experts noted that recombinant vaccines such as Novavax and Skycovione may be less effective compared to bivalent vaccines but can be used as an option for those who have concerns about side effects. Currently, all bivalent vaccines are messenger RNA (mRNA) based. Baek Soon-young, Emeritus Professor at the Catholic University Medical School, explained, "For people who experienced side effects from the initial mRNA vaccine series, recombinant vaccines can be used for additional vaccination. It is certain that these vaccines have fewer side effects, and there are definitely people who need to receive these vaccines."

Is the BA.4/5 bivalent vaccine effective against recent variants like BQ and BA.2.75?

Experts believe that the BA.4/5 bivalent vaccine will have some preventive effect against infections from BA.5-based variants such as the BQ lineage and BF.7. Professor Baek said, "BF.7 and others are subvariants of BA.5, so the vaccine is expected to be more effective in preventing infection than the BA.1-targeting vaccine. Once vaccination starts, it will be the most efficient for infection prevention."

Regarding variants like BA.2.75 and XBB, it is also explained that the vaccine will likely be more effective than the original Wuhan strain vaccine. Professor Kim Woo-joo of Korea University Guro Hospital's Infectious Diseases Department pointed out, "It can be considered more effective than the Wuhan strain vaccine, but it is still unknown which among the BA.1-targeting or BA.4/5 vaccines will be effective against BA.2.75."

Can those aged 12 to 17 receive the bivalent vaccine?

Currently, it is not possible. Pfizer's bivalent vaccine has been approved and granted emergency use authorization for additional vaccination in those aged 12 and over, but health authorities are prioritizing its use for those aged 18 and over, the common age group for bivalent vaccine administration. A Korea Disease Control and Prevention Agency official stated, "Expansion of the vaccination target to those aged 12 and over will be decided after review of the Ministry of Food and Drug Safety's approval, consultation with pediatric and adolescent experts, and examination by the Vaccination Expert Committee to determine the recommendation level."

This content was produced with the assistance of AI translation services.