Changes in population immunity against infection and severe disease from SARS-CoV-2 Omicron variants in the United States between December 2021 and November 2022

Abstract

Importance: While a substantial fraction of the US population was infected with SARS-CoV-2 during December 2021-February 2022, the subsequent evolution of population immunity against SARS-CoV-2 Omicron variants reflects the competing influences of waning protection over time and acquisition or restoration of immunity through additional infections and vaccinations. Objective: To estimate changes in population immunity against infection and severe disease due to circulating SARS-CoV-2 Omicron variants in the United States from December 2021 to October 2022, and to quantify the protection against a potential 2022-2023 winter SARS-CoV-2 wave. Design, setting, participants: Bayesian evidence synthesis of reported COVID-19 data (diagnoses, hospitalizations), vaccinations, and waning patterns for vaccine- and infection-acquired immunity, using a mathematical model of COVID-19 natural history. Main Outcomes and Measures: Population immunity against infection and severe disease from SARS-CoV-2 Omicron variants in the United States, by location (national, state, county) and week. Results: By November 10, 2022, 94% (95% CrI, 79%-99%) of the US population were estimated to have been infected by SARS-CoV-2 at least once. Combined with vaccination, 97% (95%-99%) were estimated to have some prior immunological exposure to SARS-CoV-2. Between December 1, 2021 and November 10, 2022, protection against a new Omicron infection rose from 22% (21%-23%) to 63% (51%-75%) nationally, and protection against an Omicron infection leading to severe disease increased from 61% (59%-64%) to 89% (83%-92%). Increasing first booster uptake to 55% in all states (current US coverage: 34%) and second booster uptake to 22% (current US coverage: 11%) would increase protection against infection by 4.5 percentage points (2.4-7.2) and protection against severe disease by 1.1 percentage points (1.0-1.5). Conclusions and Relevance: Effective protection against SARS-CoV-2 infection and severe disease in October 2022 was substantially higher than in December 2021. Despite this high level of protection, a more transmissible or immune evading (sub)variant, changes in behavior, or ongoing waning of immunity could lead to a new SARS-CoV-2 wave.

Characterization of SARS-CoV-2 recombinants and emerging Omicron sublineages

“…Moreover, different types of nanovaccines have been developed to help overcome COVID-19 infections caused by Omicron variants and other VOCs in the future [89]. However, the battle against SARS-CoV-2 is far from over due to its rapid evolution rate [90].…”

The COVID-19 Pandemic—A Potential Role for Antivirals in Mitigating Pandemics

“…With increasing vaccination rates and a large Omicron wave in early 2022, the overall seroprevalence rates in most of these countries are now above 90% [ 29 , 32 ], and most, but not all, non-pharmaceutical interventions have been lifted. By mid-November 2022, over 94% of the US population was estimated to have been infected with SARS-CoV-2 at least once, and half of the population was estimated to have been infected more than once [ 33 ]. Even so, most people may not have experienced multiple exposures with different variants to develop broad B- and T-cell immune responses.…”

Viral kinetics of sequential SARS-CoV-2 infections

“…An estimated 65% of the US population had at least two SARS-CoV-2 infections by November 2022, but the impact of prior infection on disease course in subsequent infections has been debated. 1 Some evidence indicates SARS-CoV-2 infection provides a temporary reduction in reinfection risk 2 and a durable reduction in the risk of COVID-19-related hospitalization and death, 3 while a handful of studies suggest that an initial SARS-CoV-2 infection may limit recovery from COVID-19 infections. 4 These contrasting findings may result from biases that can arise in population-level studies when differences in exposure history, vaccination status, and comorbidities are not fully accounted for.…”