tetano
Editor, Senior Moderator
PLoS Comput Biol
. 2024 Aug 5;20(8):e1012211.
doi: 10.1371/journal.pcbi.1012211. eCollection 2024 Aug. Impact of waning immunity against SARS-CoV-2 severity exacerbated by vaccine hesitancy
Chadi M Saad-Roy[SUP] 1 2 [/SUP], Sinead E Morris[SUP] 3 [/SUP], Mike Boots[SUP] 2 4 [/SUP], Rachel E Baker[SUP] 5 [/SUP], Bryan L Lewis[SUP] 6 [/SUP], Jeremy Farrar[SUP] 7 [/SUP], Madhav V Marathe[SUP] 6 8 [/SUP], Andrea L Graham[SUP] 9 [/SUP], Simon A Levin[SUP] 9 [/SUP], Caroline E Wagner[SUP] 10 [/SUP], C Jessica E Metcalf[SUP] 9 11 [/SUP], Bryan T Grenfell[SUP] 9 11 [/SUP]
Affiliations
The SARS-CoV-2 pandemic has generated a considerable number of infections and associated morbidity and mortality across the world. Recovery from these infections, combined with the onset of large-scale vaccination, have led to rapidly-changing population-level immunological landscapes. In turn, these complexities have highlighted a number of important unknowns related to the breadth and strength of immunity following recovery or vaccination. Using simple mathematical models, we investigate the medium-term impacts of waning immunity against severe disease on immuno-epidemiological dynamics. We find that uncertainties in the duration of severity-blocking immunity (imparted by either infection or vaccination) can lead to a large range of medium-term population-level outcomes (i.e. infection characteristics and immune landscapes). Furthermore, we show that epidemiological dynamics are sensitive to the strength and duration of underlying host immune responses; this implies that determining infection levels from hospitalizations requires accurate estimates of these immune parameters. More durable vaccines both reduce these uncertainties and alleviate the burden of SARS-CoV-2 in pessimistic outcomes. However, heterogeneity in vaccine uptake drastically changes immune landscapes toward larger fractions of individuals with waned severity-blocking immunity. In particular, if hesitancy is substantial, more robust vaccines have almost no effects on population-level immuno-epidemiology, even if vaccination rates are compensatorily high among vaccine-adopters. This pessimistic scenario for vaccination heterogeneity arises because those few individuals that are vaccine-adopters are so readily re-vaccinated that the duration of vaccinal immunity has no appreciable consequences on their immune status. Furthermore, we find that this effect is heightened if vaccine-hesitants have increased transmissibility (e.g. due to riskier behavior). Overall, our results illustrate the necessity to characterize both transmission-blocking and severity-blocking immune time scales. Our findings also underline the importance of developing robust next-generation vaccines with equitable mass vaccine deployment.
. 2024 Aug 5;20(8):e1012211.
doi: 10.1371/journal.pcbi.1012211. eCollection 2024 Aug. Impact of waning immunity against SARS-CoV-2 severity exacerbated by vaccine hesitancy
Chadi M Saad-Roy[SUP] 1 2 [/SUP], Sinead E Morris[SUP] 3 [/SUP], Mike Boots[SUP] 2 4 [/SUP], Rachel E Baker[SUP] 5 [/SUP], Bryan L Lewis[SUP] 6 [/SUP], Jeremy Farrar[SUP] 7 [/SUP], Madhav V Marathe[SUP] 6 8 [/SUP], Andrea L Graham[SUP] 9 [/SUP], Simon A Levin[SUP] 9 [/SUP], Caroline E Wagner[SUP] 10 [/SUP], C Jessica E Metcalf[SUP] 9 11 [/SUP], Bryan T Grenfell[SUP] 9 11 [/SUP]
Affiliations
- PMID: 39102402
- DOI: 10.1371/journal.pcbi.1012211
The SARS-CoV-2 pandemic has generated a considerable number of infections and associated morbidity and mortality across the world. Recovery from these infections, combined with the onset of large-scale vaccination, have led to rapidly-changing population-level immunological landscapes. In turn, these complexities have highlighted a number of important unknowns related to the breadth and strength of immunity following recovery or vaccination. Using simple mathematical models, we investigate the medium-term impacts of waning immunity against severe disease on immuno-epidemiological dynamics. We find that uncertainties in the duration of severity-blocking immunity (imparted by either infection or vaccination) can lead to a large range of medium-term population-level outcomes (i.e. infection characteristics and immune landscapes). Furthermore, we show that epidemiological dynamics are sensitive to the strength and duration of underlying host immune responses; this implies that determining infection levels from hospitalizations requires accurate estimates of these immune parameters. More durable vaccines both reduce these uncertainties and alleviate the burden of SARS-CoV-2 in pessimistic outcomes. However, heterogeneity in vaccine uptake drastically changes immune landscapes toward larger fractions of individuals with waned severity-blocking immunity. In particular, if hesitancy is substantial, more robust vaccines have almost no effects on population-level immuno-epidemiology, even if vaccination rates are compensatorily high among vaccine-adopters. This pessimistic scenario for vaccination heterogeneity arises because those few individuals that are vaccine-adopters are so readily re-vaccinated that the duration of vaccinal immunity has no appreciable consequences on their immune status. Furthermore, we find that this effect is heightened if vaccine-hesitants have increased transmissibility (e.g. due to riskier behavior). Overall, our results illustrate the necessity to characterize both transmission-blocking and severity-blocking immune time scales. Our findings also underline the importance of developing robust next-generation vaccines with equitable mass vaccine deployment.