COVID had a far greater impact on global health than the numbers of total hospitalizations and deaths may suggest. Many people, it turns out, have avoided routine medical screenings or gained weight during the pandemic.

The result: a hidden health crisis.

Missed screenings mean that some people are diagnosed with cancer later than they otherwise would have been—if they even know at all. As a consequence, their treatment is more complicated, the risk of infection greater, and their chance of survival is reduced.

Meanwhile, many people gained weight because of stress during the pandemic and lockdowns that made it difficult to exercise. In a self-reported study by the American Psychological Association, 40% of individuals said they had gained more weight during the pandemic than they had intended, with an average increase of 29 pounds. Obesity, of course, puts people at greater risk of diabetes and hypertension, which can cause serious long-term health problems.

To make matters worse, overdose deaths climbed during the pandemic, child immunizations “fell off a cliff,” and child lead poisoning screenings have declined precipitously, according to Dr. Leana Wen, emergency physician and visiting professor of health policy and management at George Washington University. In many cases, the health care industry, and particularly public health facilities that were under strain even before the pandemic, have been pushed to the brink by COVID and are unable to be proactive.

“We’ve been diverting resources elsewhere for a year,” Wen said last week during an online panel for Fortune Brainstorm Health. “It’s not like there’s a hurricane, and it strikes a region for a few days or weeks, and then you recover—this is a year.”

The remedy, doctors said, is an effort throughout the health care industry to encourage people to be tested or treated. A dentist, for example, could screen patients for diabetes and high-blood pressure—never mind that such tests are totally unrelated to cleaning teeth or filling cavities.

“We’re actually going through our patient list and calling anybody with diabetes or hypertension, anybody with a family history, and encouraging them to be screened,” said Dr. Wayne Frederick, president and Charles R. Drew professor of surgery at Howard University.

On the bright side, the pandemic has improved the situation in a few areas of health. Perhaps none is more obvious than the number of people who catch the flu, which has dropped significantly because of social distancing, masks, and increased hand washing.

“So yes, we have lost people to coronavirus at an alarming number,” said Dr. Frederick. “But flu infections are down significantly because some of the practices we’ve had to institute for the pandemic have had a secondary impact on the flu.”