Population immunity of natural infection, primary-series vaccination, and booster vaccination in Qatar during the COVID-19 pandemic: an observational study

Qassim, Suelen H.; Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; Yassine, Hadi M.; Thani, Asmaa A. Al; Al-Khatib, Hebah A.; Hasan, Mohammad R.; Al‐Kanaani, Zaina; Kuwari, Einas Al; Jeremijenko, Andrew; Kaleeckal, Anvar Hassan; Latif, Ali Nizar; Shaik, Riyazuddin Mohammad; Abdul-Rahim, Hanan F; Nasrallah, Gheyath K.; Al-Kuwari, Mohamed Ghaith; Butt, Adeel A.; Al-Romaihi, Hamad Eid; Al-Thani, Mohamed H.; Al‐Khal, Abdullatif; Bertollini, Roberto; Abu‐Raddad, Laith J.

doi:10.1016/j.eclinm.2023.102102

Cited by 9 publications

(12 citation statements)

References 52 publications

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“…The observed pattern indicated a dose-response relationship where a higher number of vaccine doses elicited greater protection. While affirming the protective effects of vaccination within this population 15,20,33,44 and corroborating global literature, 45,46 this finding further emphasizes the criticality of vaccination for older persons.…”

Section: Discussionsupporting

confidence: 84%

“…Despite a protective effect for vaccination against infection, the magnitude of protection was notably much smaller (over the entire time of follow-up) compared with that against severe COVID-19. This divergence can be attributed to the rapid waning of vaccine protection against infection, which lasts for only a few months after the last dose, 15,21,33,[44][45][46][47] and thus did not extend over the three years of follow-up in this study.…”

Section: Discussionmentioning

confidence: 95%

“…Incidence of severe COVID-19 among older adults varied throughout the pandemic reflecting differences in infection incidence (Figure S1), severity of variants, 25,[27][28][29][30][31][32] and level of population immunity. [33][34][35] Overall, nearly 2% of the population older than 50 years of age in Qatar developed severe forms of COVID-19 over a duration of three and half years of follow-up. Nearly all severe COVID-19 cases occurred before the conclusion of the first omicron wave.…”

Section: Discussionmentioning

confidence: 99%

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SARS‐CoV‐2 infection and effects of age, sex, comorbidity, and vaccination among older individuals: A national cohort study

Mahmoud,

Ayoub,

Coyle

et al. 2023

Influenza Resp Viruses

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BackgroundWe investigated the contribution of age, coexisting medical conditions, sex, and vaccination to incidence of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and of severe, critical, or fatal COVID‐19 in older adults since pandemic onset.MethodsA national retrospective cohort study was conducted in the population of Qatar aged ≥50 years between February 5, 2020 and June 15, 2023. Adjusted hazard ratios (AHRs) for infection and for severe coronavirus disease 2019 (COVID‐19) outcomes were estimated through Cox regression models.ResultsCumulative incidence was 25.01% (95% confidence interval [CI]: 24.86–25.15%) for infection and 1.59% (95% CI: 1.55–1.64%) for severe, critical, or fatal COVID‐19 after a follow‐up duration of 40.9 months. Risk of infection varied minimally by age and sex but increased significantly with coexisting conditions. Risk of infection was reduced with primary‐series vaccination (AHR: 0.91, 95% CI: 0.90–0.93) and further with first booster vaccination (AHR: 0.75, 95% CI: 0.74–0.77). Risk of severe, critical, or fatal COVID‐19 increased exponentially with age and linearly with coexisting conditions. AHRs for severe, critical, or fatal COVID‐19 were 0.86 (95% CI: 0.7–0.97) for one dose, 0.15 (95% CI: 0.13–0.17) for primary‐series vaccination, and 0.11 (95% CI: 0.08–0.14) for first booster vaccination. Sensitivity analysis restricted to only Qataris yielded similar results.ConclusionIncidence of severe COVID‐19 in older adults followed a dynamic pattern shaped by infection incidence, variant severity, and population immunity. Age, sex, and coexisting conditions were strong determinants of infection severity. Vaccine protection against severe outcomes showed a dose–response relationship, highlighting the importance of booster vaccination for older adults.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

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SARS‐CoV‐2 infection and effects of age, sex, comorbidity, and vaccination among older individuals: A national cohort study

Mahmoud,

Ayoub,

Coyle

et al. 2023

Influenza Resp Viruses

Self Cite

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“…The effectiveness of natural infection against reinfection was estimated, both overall and by time since previous infection utilizing 3-month intervals, using the test-negative, case-control study design. 2,4,[25][26][27][28][29] This design compares the odds of previous infection among SARS-CoV-2positive tests (cases) and SARS-CoV-2-negative tests (controls). 2,4,[25][26][27][28][29][30][31] Cases and controls were defined as SARS-CoV-2-positive and SARS-CoV-2-negative tests conducted during the analysis period, respectively.…”

Section: Study Population and Study Designmentioning

confidence: 99%

“…2,4,[25][26][27][28][29] This design compares the odds of previous infection among SARS-CoV-2positive tests (cases) and SARS-CoV-2-negative tests (controls). 2,4,[25][26][27][28][29][30][31] Cases and controls were defined as SARS-CoV-2-positive and SARS-CoV-2-negative tests conducted during the analysis period, respectively. SARS-CoV-2 reinfection is conventionally defined as a documented infection ≥90 days after a previous infection, to avoid misclassifying prolonged test positivity as reinfection with shorter time intervals.…”

Section: Study Population and Study Designmentioning

confidence: 99%

Protection of natural infection against reinfection with SARS-CoV-2 JN.1 variant

Chemaitelly,

Coyle,

Kacem

et al. 2024

Preprint

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This study investigated the effectiveness of natural infection in preventing reinfection with the JN.1 variant during a large JN.1 wave in Qatar, using a test-negative case-control study design. The overall effectiveness of previous infection in preventing reinfection with JN.1 was estimated at only 1.8% (95% CI: −9.3-12.6%). This effectiveness demonstrated a rapid decline over time since the previous infection, decreasing from 82.4% (95% CI: 40.9-94.7%) within 3 to less than 6 months after the previous infection to 50.9% (95% CI: −11.8-78.7%) in the subsequent 3 months, and further dropping to 18.3% (95% CI: −34.6-56.3%) in the subsequent 3 months. Ultimately, it reached a negligible level after one year. The findings show that the protection of natural infection against reinfection with JN.1 is strong only among those who were infected within the last 6 months, with variants such as XBB*. However, this protection wanes rapidly and is entirely lost one year after the previous infection. The findings support considerable immune evasion by JN.1.

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Effectiveness of two and three doses of COVID-19 mRNA vaccines against infection, symptoms, and severity in the pre-omicron era: A time-dependent gradient

Sukik,

Chemaitelly,

Ayoub

et al. 2024

Vaccine

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Population immunity of natural infection, primary-series vaccination, and booster vaccination in Qatar during the COVID-19 pandemic: an observational study

Cited by 9 publications

References 52 publications

SARS‐CoV‐2 infection and effects of age, sex, comorbidity, and vaccination among older individuals: A national cohort study

SARS‐CoV‐2 infection and effects of age, sex, comorbidity, and vaccination among older individuals: A national cohort study

Protection of natural infection against reinfection with SARS-CoV-2 JN.1 variant

Effectiveness of two and three doses of COVID-19 mRNA vaccines against infection, symptoms, and severity in the pre-omicron era: A time-dependent gradient

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