More countries are announcing a shorter waiting time for people to get a COVID-19 vaccine booster amid concerns over the Omicron variant. Australia has cut the waiting time from six months to five. South Korea has cut it down to three months as it struggles to bring down record levels of infections. UK Prime Minister Boris Johnson has warned of a looming "tidal wave" of Omicron. He says everyone above the age of 18 can get booster shots starting Monday. France has extended the eligibility for a booster dose to all adults. Is there any downside to getting a booster shot too soon? CGTN's Global Watch spoke to Doctor Alice Hyun-Kyung Tan, an Internist at MizMedi Women's Hospital in Seoul. Dr. Tan said that it is a work in process, and no one has set answers yet. But the concerns of shortening dosing intervals are that people could have sub-optimal level of antibodies and T cell response, and a lower vaccination rate.