A recent study from the Doherty Institute has challenged the notion of delaying COVID-19 booster vaccinations, finding no immunological advantage to postponing booster shots in populations with high vaccination rates. The research, published in The Journal of Clinical Investigation, supports current recommendations for individuals to receive booster doses without delay to sustain high immunity levels against SARS-CoV-2.
The randomized clinical trial investigated whether delaying a COVID-19 booster vaccine by three months would improve immunity against SARS-CoV-2. Researchers found no significant difference in immune responses between participants who received the booster immediately and those who received it three months later. Both groups exhibited similar increases in neutralizing antibodies in blood and saliva, which are crucial for protection against the virus.
"We observed no difference between participants who received the booster immediately and those who got it three months later. Both had the same immune responses, with similar increase in neutralising antibodies...in blood and saliva," said Dr. Wen Shi Lee, Research Officer at the Doherty Institute and the paper’s first author.
The study also tracked the incidence of symptomatic and asymptomatic SARS-CoV-2 infection, revealing similar rates between both groups, with approximately half of the participants experiencing infection within a year following booster administration. This suggests that delaying the booster does not reduce the risk of infection.
Booster Effectiveness and Antibody Waning
The trial utilized Moderna's bivalent Spikevax mRNA COVID-19 booster vaccine, which proved effective in triggering an immune response against Omicron strains. However, the research team observed that the elevated antibody levels were short-lived, declining significantly by day 84 and returning to pre-booster levels by day 240. This finding underscores the ongoing need for vaccines that offer longer-lasting protection and broader immunity against evolving SARS-CoV-2 variants.
Expert Recommendations
Professor Stephen Kent, Laboratory Head at the Doherty Institute and senior author of the study, emphasized the importance of maintaining robust COVID-19 booster programs to sustain population immunity, particularly as the virus continues to evolve. "Our research shows that if it has been a long time since you were last vaccinated or infected with COVID-19, delaying your booster does not lead to better immunity. So, if you are eligible, go ahead and get your booster shot," said Professor Kent.
Health authorities recommend that all adults receive COVID-19 booster vaccinations every 12 months to maintain optimal protection against severe illness, hospitalization, and death from COVID-19. This recommendation is particularly crucial for individuals aged 65 years and older and those at higher risk of severe COVID-19.
