Hospitalization of Vaccinated Older COVID-19 Patients Raises Concerns

While making sure that older adults – and those who have underlying conditions, including immunocompromise – stay up-to-date on COVID-19, that might not be enough to guarantee that they stay out of the hospital if they become infected. Find out what other measures are strongly urged by CDC-led authors of a new study showing that more than 44% of hospitalized patients had received primary vaccination and one or more booster dose.

ATLANTA – Being unvaccinated was a significant risk factor for hospitalization for COVID-19 during the Omicron BA.2–predominant period. But patients who were older adults and those with underlying medical conditions also had a much greater likelihood of being admitted to hospitals, according to a new report.

“Increased hospitalization rates among adults aged ≥65 years compared with rates among younger adults were most pronounced during the Omicron BA.2–predominant period,” according to an article in the Morbidity & Mortality Weekly Report. “Among hospitalized nonpregnant patients, 44.1% had received primary vaccination and ≥1 booster or additional dose.”

Still, the authors from the national Centers for Disease Control and Prevention and colleagues note, “Hospitalization rates among unvaccinated adults were approximately triple those of vaccinated adults.”

Public health officials advise that adults should stay up to date with COVID-19 vaccination, including booster doses, adding, “Multiple nonpharmaceutical and medical prevention measures should be used to protect persons at high risk for severe SARS-CoV-2, regardless of vaccination status.”

The authors point out that, from March 20–May 31, 2022, coinciding with the period of the Omicron BA.2 variant predominance, COVID-19–associated hospitalization rates increased among adults 65 and older relative to those in younger adults. The result was that a greater proportion of those hospitalized were 65 and older compared with the Delta and BA.1 periods. Nearly all of them also had one or more underlying medical conditions, they add.

“Hospitalization rates continue to remain higher among unvaccinated adults than among adults who received a primary COVID-19 vaccination series and ≥1 booster or additional dose,” the researchers emphasize. “Approximately one-third of hospitalized adults during the BA.2 period completed a primary series and received 1 booster or additional dose, and 5.0% received ≥2 booster or additional doses. These findings underscore the continued risk for COVID-19–associated hospitalization, particularly among unvaccinated persons and among older adults, irrespective of vaccination status.”

Background information in the report notes that older adults have experienced the highest hospitalization rates throughout the COVID-19 pandemic, although their proportion of inpatients increased during the Delta and Omicron periods. “Approximately 90% of COVID-NET hospitalizations among adults aged ≥65 years during the BA.2 period were likely admitted for COVID-19–related illness, which demonstrates that severe COVID-19 continues to affect older adults,” the authors write.

The study team suggests several reasons why older adults had a disproportionate increase in COVID-19–associated hospitalization rates:

  • Older age remains the strongest risk factor for severe COVID-19 outcomes;
  • Other risk factors include the presence of certain underlying medical conditions; and
  • Being unvaccinated or not having received a COVID-19 primary vaccination series and a booster dose.

 “Although vaccines remain effective at preventing severe illness, the proportion of hospitalized patients who are vaccinated is expected to increase as vaccination coverage increases,” the authors warn. They point out that, as of July 6, 2022, 91.6% of adults 65 and older had received a primary series, 64.4% had received 1 booster or additional dose, and 22.2% received a second booster or additional doses, which was recommended for adults 50 and older on March 29, 2022, during the BA.2 period.

In addition to not being up to date with COVID-19 vaccination, the researchers suggest increased hospitalization rates among older adults might be because COVID-19 vaccine effectiveness has been found to decline 6 months after vaccination. That waning immunity is suspected of disproportionately affecting rates among vaccinated older adults who received approval for vaccines earlier than those in other age groups.

Because of that, the authors strongly urge that, in addition to encouraging all adults to stay up to date with vaccinations, pharmacists and other healthcare professionals should implement a variety of measures to help protect those at high risk for severe illness and hospitalization because of older age, disability, moderate or severe immunocompromise, or other underlying medical conditions. Those include:

  • the use of masks or respirators that provide more protection for the wearer,
  • early access to and use of antivirals, including ritonavir-boosted nirmatrelvir (Paxlovid) and remdesivir (Veklury),
  • preexposure prophylaxis if indicated (e.g., Evusheld for persons who are immunocompromised), and
  • following guidance on testing, isolation, and managing exposures.

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