New research shows that adults who are fully vaccinated against COVID-19 rarely die from the disease, although the odds of severe outcomes and death are higher in older adults and in those with compromised immune systems and underlying conditions.

Severe COVID-19–associated outcomes and death were rare following primary vaccination, Christina Yek, MD, with the National Institutes of Health and colleagues with the US Centers for Disease Control and Prevention (CDC) COVID-19 Response Team, have reported in their study published online yesterday in the CDC’s Morbidity and Mortality Weekly Report (MMWR).

While the findings are relevant to infections during periods of pre-Delta or the Delta variant, the researchers have a caveat: The “findings might not be applicable to the risk from SARS-CoV-2 B.1.1.529 (Omicron) variant or future variants.”

Using data from 465 centers in a large US healthcare database, researchers analyzed the frequency of and risk factors for severe COVID-19 outcomes among adults who completed a primary vaccination series, defined as at least 2 weeks after receiving a second dose of a mRNA COVID-19 vaccine (Pfizer-BioNTech or Moderna) or one dose of the Johnson & Johnson COVID-19 vaccine.

Among 1,228,664 adults who completed primary vaccination during December 2020 and October 2021, 2246 (18.0 per 10,000 vaccinated persons) developed COVID-19 and 189 (1.5 per 10,000) had a severe outcome, including 36 who had a COVID-19–related death (0.3 deaths per 10,000).

Severe COVID-19 outcomes were defined as hospitalization with a diagnosis of acute respiratory failure, need for non-invasive ventilation, admission to an intensive care unit including all persons requiring invasive mechanical ventilation, or death (including discharge to hospice).

Risk for severe outcomes was higher in people aged 65 and older (adjusted odds ratio [aOR], 3.22; 95% CI: 1.81 – 5.74) and those with immunosuppression (aOR, 1.91; 95% CI: 1.37 – 2.66). Risk for severe outcomes was also higher in people with any of the following six other underlying conditions:

·         Pulmonary disease (aOR, 1.69; 95% CI: 1.31 – 2.18)

·         Liver disease (aOR, 1.68; 95% CI: 1.12 – 2.52)

·         Chronic kidney disease (aOR, 1.61; 95% CI: 1.19 – 2.19)

·         Neurologic disease (aOR, 1.54; 95% CI: 1.06 – 2.25)

·         Diabetes (aOR, 1.47; 95% CI: 1.14 – 1.89)

·         Cardiac disease (aOR,1.44; 95% CI: 1.01 – 2.06)

All adults with severe COVID-19 outcomes after completing primary vaccination had at least one risk factor, and 78% of those who died had four or more risk factors, the researchers found.

Compared with adults who received the single-shot J&J vaccine, those who got the Pfizer mRNA vaccine had similar odds of severe outcomes (aOR, 0.70; 95% CI: 0.39 – 1.26), whereas those who got the Moderna mRNA vaccine had lower odds of severe outcomes (aOR, 0.56; 95% CI: 0.32 – 0.98).

Odds of severe outcomes did not differ significantly by sex, race/ethnicity, time since primary vaccination, or whether infection occurred during the period when the Delta variant was the predominant strain.

Previous COVID-19 illness was associated with a lower likelihood of severe outcomes (aOR, 0.27; 95% CI: 0.09 – 0.84).

None of the 446 adults with COVID-19 after primary vaccination who received anti-SARS-CoV-2 monoclonal therapy (casirivimab/imdevimab [93%] or bamlanivimab/etesivimab [7%]) experienced severe outcomes.

“Even when vaccinated, persons with identifiable risk factors should receive interventions including chronic disease management, precautions to reduce exposure, additional primary and booster vaccine doses, and effective pharmaceutical therapy as indicated to reduce risk for severe COVID-19-associated outcomes,” Yek and colleagues write.

“Increasing COVID-19 vaccination coverage is a public health priority,” they add.


REFERENCE: Risk Factors for Severe COVID-19 Outcomes Among Persons Aged ≥18 Years Who Completed a Primary COVID-19 Vaccination Series — 465 Health Care Facilities, United States, December 2020–October 2021;