In a study from Northwestern Medicine, scientists found the first COVID-19 vaccination could ‘hurt’ subsequent boosters.
They found the antibodies generated by those prior vaccinations or infections can actually “hurt” the booster shots.
That’s because these antibodies rapidly “mop up” the booster from the body before it has a chance to stimulate the cells from the immune system.
In the study, the team examined 85 people who had been vaccinated with the Moderna or Pfizer-BioNTech vaccines.
The scientists found that lower antibody levels before a booster were linked to a higher-fold increase in antibody levels after the booster.
This suggests that pre-existing antibodies induced by prior vaccinations may negatively affect the level of responses induced by mRNA booster vaccines.
The scientists’ subsequent studies in mice showed that antibodies generated by prior vaccinations accelerated the clearance of the vaccine from the body, limiting the amount of vaccine available to trigger new immune responses after the booster shot.
In other words, the antibody responses generated after prior vaccinations rapidly wipe out the vaccine during a subsequent booster shot, limiting the immune response that can be generated by the booster shot
This was not caused simply by competition between antibodies and B cells for the vaccine antigen but seems to be the result of so-called “antibody effector mechanisms” that clear foreign substances from the body.
In experiments in mice, scientists found the updated omicron vaccines are superior to the original vaccines at clearing the omicron infection if the animal’s immune system has never “seen” the original SARS-CoV-2 via vaccination before.
But the relative superiority of an omicron vaccine is more limited if the animal has already had the original vaccine.
The new findings also suggest why increasing the time between vaccinations is beneficial for the immune response.
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The study was conducted by Pablo Penaloza-MacMaster et al and published in Cell Reports.
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