A major new study suggests Covid vaccines may lose effectiveness much sooner than first believed. Japanese researchers found that nearly half of participants experienced a “rapid” drop in antibodies within nine months of a booster.

The study, published in Science Translational Medicine, tracked over 2,500 adults who received Pfizer or Moderna shots. Those with falling antibody levels had about 15% higher Covid infection rates than people who maintained strong immunity. “These groups were at high risk for infection following booster vaccination,” researchers warned.

Experts say the findings highlight the need for “individualised vaccination strategies.” They suggest some people may need extra boosters or antibody therapy to stay protected. However, scientists stress more research is needed to understand why some immune systems respond less effectively.

“Vaccines saved millions of lives,” one health expert noted. “But we must keep improving protection for everyone.”

Should booster schedules be personalised to match people’s immune responses?