"Even After Booster Shot... Omicron Prevention Effect Decreases After 10 Weeks, UK Study Finds"

Vaccination. /Photo by Yonhap News

[Asia Economy Reporter Na Ye-eun] A study has found that the effectiveness of the COVID-19 vaccine booster shot (third dose) in preventing Omicron infection decreases after 10 weeks.

On the 23rd (local time), the UK Health Security Agency (UKHSA), based on research results from Imperial College London and the University of Edinburgh, stated, "There is evidence that vaccine effectiveness weakens, with a 15-25% decrease in protection around 10 weeks after receiving the booster shot." It was especially found to decline more rapidly against Omicron than Delta. However, protection against severe illness appears to persist.

While previous studies showed a decline in symptomatic protection after the second dose, this is the first data indicating that booster shot effectiveness may also decrease.

According to the study, individuals who received two doses of the AstraZeneca vaccine and then a third dose with Pfizer or Moderna vaccines had about 60% protection 2 to 4 weeks after the booster.

By vaccine type, Pfizer booster effectiveness dropped to 35% after 10 weeks. Moderna booster effectiveness decreased to 45%, but maintained a higher level than Pfizer.

Those who received the first and second doses with Pfizer and a Moderna booster maintained 70-75% effectiveness for up to 9 weeks.

Additionally, UKHSA estimated that "the probability of emergency room visits for Omicron-infected individuals is 31-45% lower than for Delta-infected individuals, and the probability of hospitalization is 50-70% lower," but noted, "Since the number of Omicron patients in hospitals is low and most confirmed cases are young, this analysis is preliminary and has significant uncertainty."

Meanwhile, the UK Joint Committee on Vaccination and Immunisation (JCVI) has begun evaluating whether to proceed with a fourth dose based on these research results.

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