Infectious Disease

COVID-19 mRNA vaccines 87% effective in preventing hospital stays amid delta surge

September 30, 2021

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Bajema does not report any relevant financial information. Co-author Vincent C. Marconi, MD, of the Atlanta Veterans Affairs Medical Center in Georgia, reports on research grants from Eli Lilly & Co., Gilead Sciences, and ViiV Healthcare.

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Among U.S. veterans at five Veterans Affairs medical centers, mRNA vaccines were about 87% effective in preventing COVID-19 hospitalizations amid the continued surge in Delta variants, according to the CDC.

The researchers, who published their results in the CDC’s Morbidity and Mortality Weekly Report, also concluded that the mRNA vaccines were 80% effective at preventing COVID-19-related hospitalization in adults aged 65 and older to prevent, compared to 95% in people aged 18 to 64 years.

US veterans at five Veterans Affairs medical centers were found to have had mRNA vaccines, according to Bajema KL et al. Morb Mortal Wkly Rep. 2021; doi: 10.15585 / mmwr.mm7037e3.

“COVID-19 mRNA vaccines (Pfizer-BioNTech and Moderna) have been shown to be highly protective against COVID-19-associated hospitalizations.” Kristina L. Bajema, MD, of the CDC COVID-19 Response Team, and colleagues wrote.

“Data on levels of protection from hospitalization among disproportionately affected populations in the United States are limited, especially during periods when the B.1.617.2 (Delta) variant of SARS-CoV-2, the virus that causes COVID-19 , predominates, “they added. “US veterans are older, more racially diverse, and have a higher prevalence of underlying diseases than individuals in the general US population.”

Kristina L. Bajema

To analyze the effectiveness of mRNA vaccines against hospital stays for COVID-19 in US veterans in connection with the dominance of the Delta variants, Bajema and colleagues conducted a test-negative case at five Veterans Affairs Medical Centers from February 1 to August – Control adult assessment by 6. These centers were located in Atlanta; the Bronx, New York; Houston; Los Angeles; and Palo Alto, California. Patient selection criteria included a COVID-19-like illness and a molecular test for SARS-CoV-2 performed within 14 days of admission or during the first 72 hours after hospitalization.

Patients with COVID-19-like illness with positive SARS-CoV-2 test results were included in the study as case participants, patients with negative tests as controls. Researchers used electronic health records to review data on patient demographics, underlying medical conditions, the disease present, SARS-CoV-2 test results, COVID-19 vaccination history, and clinical history during the hospital stay.

To assess the effectiveness of the vaccine, the researchers used multivariable logistic regression to compare the chances of full vaccination between case patients and controls, using the medical center location, date of admission, age, sex, race, and more took into account ethnicity. Complete vaccination was defined as receiving both doses of an mRNA vaccine – either Pfizer-BioNTech or Moderna – at least 14 days before performing the SARS-CoV-2 test.

A total of 1,175 participants – 388 case patients and 787 controls – were included in the analysis. Of these patients, 93% were men with a mean age of 68 years, 48.9% were black, 40.4% white, 7.9% Hispanic American of any race, and 44.4% had a Charlson Comorbidity Index of 3 or higher. A total of 13.9% of the case patients and 48% of the controls were fully vaccinated. Among the 171 case patients with a certain SARS-CoV-2 ancestry, Delta was the predominant variant at all locations until July.

According to the researchers, the overall adjusted efficacy of the mRNA vaccine against COVID-19 hospitalization was 86.8% (95% CI, 80.4% to 91.1%). In addition, vaccine efficacy was similar both before and during the ramp up of the Delta variant, at 84.1% for the February 1st to June 30th, compared with 89.3% for the July 1st to August 6th. The vaccine effectiveness was 79.8% (95% CI, 67.7% -87.4%) in adults aged 65 years and older and 95.1% (95% CI, 89.1% -97.8) %) among 18- to 64-year-olds.

“This study of US veterans hospitalized at five Veterans Affairs Medical Centers found that mRNA COVID-19 vaccines were highly effective in preventing COVID-19-related hospitalization, even during times of widespread use Circulation of the Delta variant, ”Bajema told Healio Rheumatology. “These vaccines were effective against hospitalization in all age groups, although less so in US veterans 65 and over.”

“These results are reassuring as the US veterans in this rating were older and more racially diverse,” added Bajema. “They were also more likely to develop underlying diseases, putting them at higher risk for severe COVID-19 than the general US population.”

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