Even compared to a group of 73 people who had weathered a bout with COVID-19and went on to get two doses of an mRNA vaccine, the boosted group’s median antibody level was 68% higher.

Study leader Alexis Demonbreun, a cell biologist at Northwestern University’s Feinberg School of Medicine, said the data demonstrate that no matter how well protected a vaccinated person may think she is, getting a booster shot is likely to increase her neutralizing antibodies — and with it, her immunity — considerably. And because scientists expect large antibody responses to create more durable immunity, the protection afforded by the booster should last longer than the initial two-shot regimen did.

“If I was going to Vegas, I’d bet on the booster rather than getting the virus to protect me,” Demonbreun said.