Publication date: Jan 29, 2025
Early investigation revealed a reduced risk of SARS-CoV-2 infection among social contacts of COVID-19 vaccinated individuals, referred to as indirect protection. However, indirect protection from SARS-CoV-2 infection-acquired immunity and its comparative strength and durability to vaccine-derived indirect protection in the current epidemiologic context of high levels of vaccination, prior infection, and novel variants are not well characterized. Here, we show that both vaccine-derived and infection-acquired immunity independently yield indirect protection to close social contacts with key differences in their strength and waning. Analyzing anonymized SARS-CoV-2 surveillance data from 9,625 residents in California state prisons from December 2021 to December 2022, we find that vaccine-derived indirect protection against Omicron SARS-CoV-2 infection is strongest within three months of COVID-19 vaccination [30% (95% confidence interval: 20-38%)] with subsequent modest protection. Infection-acquired immunity provides 38% (24-50%) indirect protection for 6 months after SARS-CoV-2 infection, with moderate indirect protection persisting for over one year. Variant-targeted vaccines (bivalent formulation including Omicron subvariants BA. 4/BA. 5) confer strong indirect protection for at least three months [40% (3-63%)]. These results demonstrate that both vaccine-derived and infection-acquired immunity can reduce SARS-CoV-2 transmission which is important for understanding long-term transmission dynamics and can guide public health intervention, especially in high-risk environments such as prisons.
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| Concepts | Keywords |
|---|---|
| California | Acquired |
| December | Contacts |
| Epidemiology | Cov |
| Vaccines | Derived |
| Durability | |
| Immunity | |
| Indirect | |
| Infection | |
| Months | |
| Protection | |
| Risk | |
| Sars | |
| Social | |
| Strength | |
| Vaccine |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | SARS-CoV-2 infection |
| pathway | REACTOME | SARS-CoV-2 Infection |
| disease | MESH | infection |
| disease | IDO | intervention |
| disease | MESH | reinfections |
| disease | IDO | susceptibility |
| drug | DRUGBANK | Methionine |
| disease | MESH | influenza |
| disease | IDO | history |
| disease | IDO | immune response |
| disease | IDO | host |
| disease | IDO | process |
| disease | MESH | death |
| disease | MESH | complications |
| disease | MESH | long COVID |
| drug | DRUGBANK | Etoperidone |
| disease | MESH | myocarditis |
| disease | MESH | breakthrough infection |
| drug | DRUGBANK | Ilex paraguariensis leaf |
| drug | DRUGBANK | Cysteamine |
| disease | MESH | infection transmission |
| disease | MESH | privacy |
| disease | MESH | Infectious Diseases |
| drug | DRUGBANK | Coenzyme M |
| disease | MESH | Emergency |
| pathway | REACTOME | Release |
| pathway | REACTOME | Reproduction |