In a new study from the University of Sydney, researchers found vaccines are less effective against some COVID-19 variants and boosting may be required within one year to maintain efficacy above 50%.
They conducted an analysis that can help inform the COVID-19 response by identifying an ‘immune correlate’ of vaccine protection.
This research is crucial because it shows that scientists can predict vaccine efficacy from a relatively simple laboratory test.
In the study, the team analyzed existing data on how effective neutralizing antibody responses were in infected and vaccinated individuals against different variants.
They found that antibodies induced by infection or vaccination were less protective against the variants of concern and that over time, there was a drop in neutralizing antibodies, and these changes could be used to predict vaccine efficacy.
Vaccines work well in the first months after vaccination and against the viruses that were used to make them.
However, the team showed reduced vaccine efficacy against COVID-19 disease resulting from other variants, such as Delta, which declined with time.
The analysis was able to pre-emptively predict this decline based on an analysis of antibody levels.
The researchers tested this against the variants of concern, including Delta, and found that the model continues to provide a robust prediction of immune protection, despite the differences between the viral sequence seen in variants like Delta.
A major implication of the research was that booster shots of the COVID-19 vaccine were needed to maintain immune protection across a population.
Without boosters, protection from symptomatic COVID may drop below 50% after six months, which means more people will become infected.
The analysis also found that a booster shot within a year increases immunity to higher levels than those seen after a full primary vaccination schedule.
If you care about COVID vaccines, please read studies about vaccines beat natural immunity in fight against COVID-19 and findings of COVID-19 vaccines effectively prevent hospitalization in older people.
For more information about COVID and your health, please see recent studies about what happens when the COVID-19 vaccines enter the body and results showing that COVID vaccines less effective for people with these two health issues.
The study is published in The Lancet Microbe. One author of the study is Professor Jamie Triccas.
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