Prior Pneumonia Cases May Pose Unseen Covid Dangers, Harvard Study Finds

(Bloomberg) -- An earlier case of pneumonia appears to be a surprisingly strong indicator of whether someone infected with Covid-19 faces a higher risk of severe disease and death, Harvard University researchers said.

A prior episode of pneumonia was the second-greatest overall risk factor for death from Covid-19, according to a study of medical records from almost 17,000 patients. The top predictor of risk is age, with the risk increasing as people get older.

By itself, a single pneumonia case probably doesn't put someone at high risk, the researchers cautioned. Rather, it's more likely an indicator of underlying chronic disease -- such as chronic obstructive pulmonary disease or interstitial lung disease -- that's gone undiagnosed, they said.

Health officials have broadly prioritized older people and health workers to be first in line for potentially life-saving Covid vaccines, because of their risk of death and exposure to the disease. A machine-learning analysis of mortality patterns can help pinpoint others at high risk and alert doctors, officials and patients to respond, according to the study's leader, Hossein Estiri, an assistant professor at the Harvard-affiliated Massachusetts General Hospital's Laboratory of Computer Science.

“We could save tens of thousands of lives by prioritizing vaccines for the most vulnerable,” Estiri said in an interview. The study was published Thursday in NPJ Digital Medicine, one of the Nature group of journals.

Some 108 million people have been vaccinated against Covid worldwide, 35 million of them in the U.S., as of Wednesday, according to Bloomberg's vaccine tracker. Widespread use of vaccines is not only key to saving lives; it can stem the emergence of fast-spreading variants and help restore economies that have been strangled by the pandemic.

Yet U.S. states have varying levels of success in vaccine distribution due to issues ranging from supply to trouble reaching eligible populations. Educating people about their risk level, based on existing medical conditions, could help those who need vaccines to become less reticent about getting immunized and seeking out shots, the researchers said.

“Let's get people to self-identify and get to the vaccine clinics,” said Shawn Murphy, a neurologist at Massachusetts General Hospital and associate director of the computer science lab who helped write the study. “Let them understand that they need the vaccine and vote with their feet.”

Missed Conditions

It's common for cases of chronic pneumonia to be missed, said Zachary Strasser, a Harvard postdoctoral fellow at Massachusetts General who also contributed to the study. Still, it's probably not necessary to investigate to see whether there is chronic lung disease to classify someone as high-risk, they said, since prior cases of pneumonia are such a strong indicator.

Other conditions that probably play a greater role in Covid deaths than currently thought include high blood pressure and chronic kidney disease, the researchers said. In people from the ages of 45 to 65, conditions such as gastrointestinal bleeding and breast cancer were associated with increased risk of death from Covid.

The study was undertaken among patients with confirmed Covid-19 diagnoses from March to November of 2020. Earlier studies have come from limited patient numbers, the researchers said.

Electronic medical records systems are widespread, they said, and more hospitals and health systems should examine them to see which of their patients are at highest risk of death from Covid.

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