Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs
Objectives To evaluate the benefits of vaccination on the case fatality rate (CFR) for COVID-19 infections.Design, setting and participants The US Department of Veterans Affairs has 130 medical centres. We created multivariate models from these data—339 772 patients with COVID-19—as of 30 September...
| Main Authors: | , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMJ Publishing Group
2022-12-01
|
| Series: | BMJ Open |
| Online Access: | https://bmjopen.bmj.com/content/12/12/e064135.full |
| _version_ | 1797787295434145792 |
|---|---|
| author | Heather M Campbell Glen H Murata Allison E Murata Douglas J Perkins Jenny T Mao Brent Wagner Benjamin H McMahon Curt H Hagedorn |
| author_facet | Heather M Campbell Glen H Murata Allison E Murata Douglas J Perkins Jenny T Mao Brent Wagner Benjamin H McMahon Curt H Hagedorn |
| author_sort | Heather M Campbell |
| collection | DOAJ |
| description | Objectives To evaluate the benefits of vaccination on the case fatality rate (CFR) for COVID-19 infections.Design, setting and participants The US Department of Veterans Affairs has 130 medical centres. We created multivariate models from these data—339 772 patients with COVID-19—as of 30 September 2021.Outcome measures The primary outcome for all models was death within 60 days of the diagnosis. Logistic regression was used to derive adjusted ORs for vaccination and infection with Delta versus earlier variants. Models were adjusted for confounding factors, including demographics, comorbidity indices and novel parameters representing prior diagnoses, vital signs/baseline laboratory tests and outpatient treatments. Patients with a Delta infection were divided into eight cohorts based on the time from vaccination to diagnosis. A common model was used to estimate the odds of death associated with vaccination for each cohort relative to that of unvaccinated patients.Results 9.1% of subjects were vaccinated. 21.5% had the Delta variant. 18 120 patients (5.33%) died within 60 days of their diagnoses. The adjusted OR for a Delta infection was 1.87±0.05, which corresponds to a relative risk (RR) of 1.78. The overall adjusted OR for prior vaccination was 0.280±0.011 corresponding to an RR of 0.291. Raw CFR rose steadily after 10–14 weeks. The OR for vaccination remained stable for 10–34 weeks.Conclusions Our CFR model controls for the severity of confounding factors and priority of vaccination, rather than solely using the presence of comorbidities. Our results confirm that Delta was more lethal than earlier variants and that vaccination is an effective means of preventing death. After adjusting for major selection biases, we found no evidence that the benefits of vaccination on CFR declined over 34 weeks. We suggest that this model can be used to evaluate vaccines designed for emerging variants. |
| first_indexed | 2024-03-13T01:19:57Z |
| format | Article |
| id | doaj.art-f060b4d73e85453091f906c8242704b4 |
| institution | Directory Open Access Journal |
| issn | 2044-6055 |
| language | English |
| last_indexed | 2024-03-13T01:19:57Z |
| publishDate | 2022-12-01 |
| publisher | BMJ Publishing Group |
| record_format | Article |
| series | BMJ Open |
| spelling | doaj.art-f060b4d73e85453091f906c8242704b42023-07-05T05:00:07ZengBMJ Publishing GroupBMJ Open2044-60552022-12-01121210.1136/bmjopen-2022-064135Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans AffairsHeather M Campbell0Glen H Murata1Allison E Murata2Douglas J Perkins3Jenny T Mao4Brent Wagner5Benjamin H McMahon6Curt H Hagedorn7VA Cooperative Studies Program, Clinical Research Pharmacy Coordinating Center, Albuquerque, New Mexico, USAVA Cooperative Studies Program, Clinical Research Pharmacy Coordinating Center, Albuquerque, New Mexico, USAClinical Research Pharmacy Coordinating Center, VHA Cooperative Studies Program, Albuquerque, New Mexico, USACenter for Global Health, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USAMedicine Service, New Mexico VA Health Care System, Albuquerque, New Mexico, USAResearch Service, New Mexico VA Health Care System, Albuquerque, New Mexico, USATheoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, New Mexico, USAMedicine Service, New Mexico VA Health Care System, Albuquerque, New Mexico, USAObjectives To evaluate the benefits of vaccination on the case fatality rate (CFR) for COVID-19 infections.Design, setting and participants The US Department of Veterans Affairs has 130 medical centres. We created multivariate models from these data—339 772 patients with COVID-19—as of 30 September 2021.Outcome measures The primary outcome for all models was death within 60 days of the diagnosis. Logistic regression was used to derive adjusted ORs for vaccination and infection with Delta versus earlier variants. Models were adjusted for confounding factors, including demographics, comorbidity indices and novel parameters representing prior diagnoses, vital signs/baseline laboratory tests and outpatient treatments. Patients with a Delta infection were divided into eight cohorts based on the time from vaccination to diagnosis. A common model was used to estimate the odds of death associated with vaccination for each cohort relative to that of unvaccinated patients.Results 9.1% of subjects were vaccinated. 21.5% had the Delta variant. 18 120 patients (5.33%) died within 60 days of their diagnoses. The adjusted OR for a Delta infection was 1.87±0.05, which corresponds to a relative risk (RR) of 1.78. The overall adjusted OR for prior vaccination was 0.280±0.011 corresponding to an RR of 0.291. Raw CFR rose steadily after 10–14 weeks. The OR for vaccination remained stable for 10–34 weeks.Conclusions Our CFR model controls for the severity of confounding factors and priority of vaccination, rather than solely using the presence of comorbidities. Our results confirm that Delta was more lethal than earlier variants and that vaccination is an effective means of preventing death. After adjusting for major selection biases, we found no evidence that the benefits of vaccination on CFR declined over 34 weeks. We suggest that this model can be used to evaluate vaccines designed for emerging variants.https://bmjopen.bmj.com/content/12/12/e064135.full |
| spellingShingle | Heather M Campbell Glen H Murata Allison E Murata Douglas J Perkins Jenny T Mao Brent Wagner Benjamin H McMahon Curt H Hagedorn Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs BMJ Open |
| title | Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs |
| title_full | Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs |
| title_fullStr | Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs |
| title_full_unstemmed | Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs |
| title_short | Effect of vaccination on the case fatality rate for COVID-19 infections 2020–2021: multivariate modelling of data from the US Department of Veterans Affairs |
| title_sort | effect of vaccination on the case fatality rate for covid 19 infections 2020 2021 multivariate modelling of data from the us department of veterans affairs |
| url | https://bmjopen.bmj.com/content/12/12/e064135.full |
| work_keys_str_mv | AT heathermcampbell effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT glenhmurata effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT allisonemurata effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT douglasjperkins effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT jennytmao effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT brentwagner effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT benjaminhmcmahon effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs AT curthhagedorn effectofvaccinationonthecasefatalityrateforcovid19infections20202021multivariatemodellingofdatafromtheusdepartmentofveteransaffairs |