Thread by @ejustin46

𝙏𝙝𝙚 𝙢𝙞𝙨𝙩𝙖𝙠𝙚 𝙤𝙛 𝙗𝙚𝙡𝙞𝙚𝙫𝙞𝙣𝙜 𝙞𝙣 "𝙝𝙮𝙙𝙧𝙞𝙙 𝙞𝙢𝙢𝙪𝙣𝙞𝙩𝙮"

"𝘏𝘺𝘣𝘳𝘪𝘥 𝘪𝘮𝘮𝘶𝘯𝘪𝘵𝘺 𝘩𝘢𝘴 𝘭𝘪𝘮𝘪𝘵𝘦𝘥 𝘪𝘮𝘱𝘢𝘤𝘵 𝘰𝘯 𝘧𝘶𝘵𝘶𝘳𝘦 𝘊𝘖𝘝𝘐𝘋-19 𝘸𝘢𝘷𝘦𝘴 𝘸𝘪𝘵𝘩 𝘪𝘮𝘮𝘶𝘯𝘦-𝘦𝘴𝘤𝘢𝘱𝘦 𝘷𝘢𝘳𝘪𝘢𝘯𝘵𝘴"
bmcinfectdis.biomedcentral.com/articles/10.11…

2) The study uses an agent-based model to simulate COVID-19 transmission and evaluate the impact of hybrid immunity on future epidemic waves. Hybrid immunity refers to immunity from both past infection and vaccination.

3) It considers scenarios with different population age structures ("older" vs "younger"), vaccination coverage levels (20%, 50%, 80%), and timeline of vaccination rollout and infection waves.
For a second wave caused by the same Omicron variant, high vaccination coverage (>50%)

4) ...can delay and suppress future waves compared to low (20%) coverage, especially if past infection rates were also high (>50%).
Older populations consistently experience worse clinical outcomes like deaths than younger populations, even with the same attack rates.

5) Higher vaccination is more important in older populations to protect high-risk groups.
If the second wave is caused by an Omicron immune escape variant, previously observed protective effects of vaccination are reduced. Past and future attack rates show a linear relationship

6) ...and future rates can exceed past rates.
The benefits of vaccination and hybrid immunity depend on many factors like demography, vaccine efficacy, and variants. Hybrid immunity landscapes will become more complex over time with multiple exposures and variants.

7) In summary, the study shows how vaccination can help mitigate future COVID-19 waves, but its impact depends strongly on population characteristics, variants, and waning immunity over time.

Thanks for reading 🙏