tetano
Editor, Senior Moderator
Nat Commun
. 2026 Aug 8;17(1):8014.
doi: 10.1038/s41467-026-76312-x.
Healthy vaccinee effect in the evaluation of updated COVID-19 vaccines in elderly populations
Johan Lyth[SUP] 1 [/SUP], Armin Spreco[SUP] 2 [/SUP], Jorma Hinkula[SUP] 3 [/SUP], Olle Björneld[SUP] 4 5 [/SUP], Olle Eriksson[SUP] 6 [/SUP], Dennis Nordvall[SUP] 6 [/SUP], Örjan Dahlström[SUP] 7 [/SUP], Elin A Gursky[SUP] 8 [/SUP], Thomas Schön[SUP] 3 9 [/SUP], Toomas Timpka[SUP] 10 11 [/SUP]
Affiliations
Established determinants of health in the elderly help guide routines for indicated vaccine administration, while unmeasured frailty may limit vaccine access. We evaluate the performance of the 2024-2025 COVID-19 vaccine adapted to the Omicron JN.1 lineage in a Swedish population aged ≥65 years (N = 245 696). Vaccine effectiveness (VE) on COVID-19-related hospitalization and a negative control outcome (NCO; all-cause mortality) are assessed in various cohorts between October 1, 2024 to March 31, 2025. The VE was 75% (95% CI 70%-79%) overall, and 84% (95% CI 80%-87%) and 65% (95% CI 34%-82%) in individuals with and without vaccination with the prior updated COVID-19 vaccine in 2023-2024, respectively. The NCO in individuals exposed to the study vaccine in 2024-2025 was half of that seen in those not exposed to the vaccine (HR 0.43 [95% CI 0.40-0.45]). Removing individuals hospitalized with COVID-19 from this population did not change the difference in NCO (HR 0.43 [95% CI 0.41-0.46]). These findings suggest the presence of selection effects arising from under-provision of health services to elderly individuals with frailty. The healthy vaccinee effect should be considered in observational studies of the effectiveness of updated COVID-19 vaccines in elderly populations.
. 2026 Aug 8;17(1):8014.
doi: 10.1038/s41467-026-76312-x.
Healthy vaccinee effect in the evaluation of updated COVID-19 vaccines in elderly populations
Johan Lyth[SUP] 1 [/SUP], Armin Spreco[SUP] 2 [/SUP], Jorma Hinkula[SUP] 3 [/SUP], Olle Björneld[SUP] 4 5 [/SUP], Olle Eriksson[SUP] 6 [/SUP], Dennis Nordvall[SUP] 6 [/SUP], Örjan Dahlström[SUP] 7 [/SUP], Elin A Gursky[SUP] 8 [/SUP], Thomas Schön[SUP] 3 9 [/SUP], Toomas Timpka[SUP] 10 11 [/SUP]
Affiliations
- PMID: 42570961
- PMCID: PMC13452808
- DOI: 10.1038/s41467-026-76312-x
Established determinants of health in the elderly help guide routines for indicated vaccine administration, while unmeasured frailty may limit vaccine access. We evaluate the performance of the 2024-2025 COVID-19 vaccine adapted to the Omicron JN.1 lineage in a Swedish population aged ≥65 years (N = 245 696). Vaccine effectiveness (VE) on COVID-19-related hospitalization and a negative control outcome (NCO; all-cause mortality) are assessed in various cohorts between October 1, 2024 to March 31, 2025. The VE was 75% (95% CI 70%-79%) overall, and 84% (95% CI 80%-87%) and 65% (95% CI 34%-82%) in individuals with and without vaccination with the prior updated COVID-19 vaccine in 2023-2024, respectively. The NCO in individuals exposed to the study vaccine in 2024-2025 was half of that seen in those not exposed to the vaccine (HR 0.43 [95% CI 0.40-0.45]). Removing individuals hospitalized with COVID-19 from this population did not change the difference in NCO (HR 0.43 [95% CI 0.41-0.46]). These findings suggest the presence of selection effects arising from under-provision of health services to elderly individuals with frailty. The healthy vaccinee effect should be considered in observational studies of the effectiveness of updated COVID-19 vaccines in elderly populations.