CDC Clarifies Risk for More Severe COVID-19 Outcomes

Damian McNamara

June 25, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Obesity poses a greater risk as an underlying condition when someone develops COVID-19, whereas newer evidence suggests hypertension poses a lower risk compared with the reports at the beginning of the pandemic in the United States, officials with the Centers for Disease Control and Prevention (CDC) announced today in a press briefing.

CDC Director Robert Redfield, MD, also told reporters on the briefing that the number of people infected with the novel coronavirus might be 10 times higher than reported.

Among those who are infected, the connection between obesity and more severe COVID-19 outcomes — defined as hospitalization, ICU admission, and/or death — early on was "most obvious among people with a BMI over 40," said Jay C. Butler, MD, CDC deputy director of infectious diseases and COVID-19 response incident manager.

"Now with more data, it appears that even obesity at a BMI over 30 may increase the risk as well," he said.

The potential contribution of hypertension to elevated risk shifted over time as well, Butler added during the briefing. He explained that high blood pressure is a risk factor for a number of conditions, and more recent studies helped CDC officials better tease out the individual risk associated with COVID-19.

The agency expanded its list of underlying conditions associated with the more severe COVID-19 outcomes. For example, in addition to a BMI of 30 or more, evidence suggests serious heart conditions, sickle cell disease, type 2 diabetes and other conditions elevate the risk for severe illness. Joining hypertension in the "might be at increased risk" category are people with moderate-to-severe asthma, dementia, and cystic fibrosis.

"We are talking about the strength of evidence rather than upgrading or downgrading the level of risk" for each of these conditions, Butler said.

No More Specific Age Distinction

The CDC also removed an age cutoff associated with elevated risk for more serious COVID-19, previously set at older than 65 years. Instead, it's more of a continuum. "As you get older, your risk for hospitalization, intensive care, and death increases," said Redfield.

Although increased age is an independent risk factor, the agency acknowledged that older Americans tend to have more underlying conditions as well. 

Pregnancy Risks Linked to COVID-19

Pregnant women with COVID-19 appear to be at elevated risk for hospitalization, intensive care unit admission, and use of mechanical ventilation, according to research published online today in Morbidity and Mortality Weekly Report (MMWR). At the same time, however, this study of 8207 pregnant women with confirmed COVID-19 infection had no significantly increased risk of death.

"The good news is that the data we have so far is that pregnant women are not at increased risk of death," Dana Meaney-Delman, MD, MPH, COVID-19 deputy incident manager at the CDC, said during the briefing.

"But we do see increased risk of ICU admission and mechanical ventilation," she added. So it remains "important to get the message out there that pregnant women need to take precautions."

Of 91,412 (28%) women with laboratory-confirmed infections reported to the CDC between January 22 and June 7, 9% were pregnant.

Among the women with COVID-19, almost 32% of pregnant women were hospitalized compared with 6% of women who were not pregnant. Furthermore, the pregnant women were 50% more likely to be admitted to an ICU (adjusted relative risk [aRR], 1.5; 95% confidence interval, 1.2 - 1.8) and 70% more likely to be placed on mechanical ventilation (aRR, 1.7; 95% CI, 1.2 - 2.4). These analyses adjusted for age, underlying conditions, and race/ethnicity.

Multiply Confirmed Cases By 10

Addressing a recent increasing number of cases in the United States, Redfield said "there are a number of states, particularly in the Southeast and the Southwest, that are seeing increases in COVID-19 cases."

Many factors are driving the increase, he added, including outbreaks in particularly challenging settings, increased testing, and community transmission.

"This virus causes so much asymptomatic infection, we don't know the exact number," Redfield said.

More data are coming in from antibody testing and public health surveillance. "We probably recognized about 10% of the outbreak during March, April, and May," he said. The agency is working now to enhance detection closer to real time, he added.

"The best estimate for now is, for everyone diagnosed there were 10 other cases," Redfield said. Although data will be refined in next few weeks, "that is a good rough estimate for now."

At the same time that the number of positive cases is increasing, data is pointing to a higher infection rate among younger people, as reported by WebMD Health News.

"Obviously we are seeing infections that are targeting younger individuals, as in Florida or the Southeast and Southwest of the country," Redfield said. "In the past, I don't think we diagnosed these infections."

Redfield "remains concerned" about the public health messaging for people under age 45 or even under 30. "The impact of COVID-19 on them may not be associated with hospitalization and death, but they do act as transmission connectors to individuals who could be at higher risk."

"Everyone needs to understand there is some risk of severe illness, including among young people," he added.

Future Concerns

"It's clear that many individuals in this nation are still susceptible," Redfield said. The risk will vary with different prevalence rates in different states.

He estimated that between 5% to 8% of Americans have experienced COVID-19 infection so far, "whether they recognize it or not." This also means that greater than 90% of the public has not experienced the virus, although they are susceptible.

"This outbreak is not over, this pandemic is not over, and we need to continue to take steps we know are effective at limiting COVID-19," he said. The most powerful tool we have is social distancing. He emphasized the need to maintain 6 feet of distance with others, wearing a face covering "when we cannot maintain social distancing," and continuing frequent hand hygiene practices.

"As we go into the fall and winter, these will be important defense mechanisms," Redfield said. 

Follow Damian McNamara on Twitter: @MedReporter.

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