The study investigates the relationship between neutralization titers and immune protection from symptomatic SARS-CoV-2 infection. Using data from seven current vaccines and convalescent cohorts, the researchers estimate that a 50% protective neutralization level is 20.2% of the mean convalescent level (95% CI = 14.4–28.4%). For severe infection, the protective neutralization level is significantly lower at 3% of the mean convalescent level (95% CI = 0.7–13%, P = 0.0004). Modeling predicts a significant loss in protection from SARS-CoV-2 infection over the first 250 days after vaccination, but protection from severe disease should be largely retained. Neutralization titers against some variants of concern are reduced compared to the vaccine strain, and the model predicts the relationship between neutralization and efficacy against these variants. The study concludes that neutralization levels are highly predictive of immune protection and provides a model to assist in developing vaccine strategies to control the pandemic.The study investigates the relationship between neutralization titers and immune protection from symptomatic SARS-CoV-2 infection. Using data from seven current vaccines and convalescent cohorts, the researchers estimate that a 50% protective neutralization level is 20.2% of the mean convalescent level (95% CI = 14.4–28.4%). For severe infection, the protective neutralization level is significantly lower at 3% of the mean convalescent level (95% CI = 0.7–13%, P = 0.0004). Modeling predicts a significant loss in protection from SARS-CoV-2 infection over the first 250 days after vaccination, but protection from severe disease should be largely retained. Neutralization titers against some variants of concern are reduced compared to the vaccine strain, and the model predicts the relationship between neutralization and efficacy against these variants. The study concludes that neutralization levels are highly predictive of immune protection and provides a model to assist in developing vaccine strategies to control the pandemic.