SARS-CoV-2 elicits non-sterilizing immunity and evades vaccine-induced immunity: implications for future vaccination strategies

Neither vaccination nor natural infection result in long-lasting protection against SARS-COV-2 infection and transmission, but both reduce the risk of severe COVID-19. To generate insights into optimal vaccination strategies for prevention of severe COVID-19 in the population, we extended a Susceptible-Exposed-Infectious-Removed (SEIR) mathematical model to compare the impact of vaccines that are highly protective against severe COVID-19 but not against infection and transmission, with those that block SARS-CoV-2 infection. Our analysis shows that vaccination strategies focusing on the prevention of severe COVID-19 are more effective than those focusing on creating of herd immunity. Key uncertainties that would affect the choice of vaccination strategies are: (1) the duration of protection against severe disease, (2) the protection against severe disease from variants that escape vaccine-induced immunity, (3) the incidence of long-COVID and level of protection provided by the vaccine, and (4) the rate of serious adverse events following vaccination, stratified by demographic variables.

Automated summary

Neither vaccination nor natural infection provide long-lasting protection against SARS-COV-2 infection and transmission, but both reduce the risk of severe COVID-19. To determine optimal vaccination strategies for preventing severe COVID-19 in the population, a mathematical model was extended to compare the impact of vaccines highly protective against severe disease but not against infection, with vaccines that block SARS-CoV-2 infection. The analysis shows that vaccination strategies focusing on preventing severe disease are more effective than strategies aiming to achieve herd immunity. Key uncertainties influencing the choice of vaccination strategies include the duration of protection, vaccine effectiveness against variant strains, incidence of long-COVID, and adverse events following vaccination stratified by demographics.