The chances of dying from COVID-19 have fallen precipitously since the pandemic began, according to two new peer-reviewed studies.
One study, from researchers at New York University's Grossman School of Medicine, found that the death rate has gone down substantially among all age groups.
Patients treated by NYU's health system had a 25.6% chance of dying when the pandemic began but that number has fallen to 7.6% in recent weeks, according to the study, which will be published in the Journal of Hospital Medicine next week.
The researchers identified multiple reasons for the drop, including increased experience with the virus among health workers, lower hospital capacity, the availability of new treatments, earlier intervention, higher community awareness, and "lower viral load exposure from increasing mask wearing and social distancing." The researchers added that it is also possible that "earlier periods had a more virulent circulating strain."
"Our findings suggest that while COVID-19 remains a terrible disease, our efforts to improve treatment are probably working," co-author Leora Horwitz said in a statement. "Even in the absence of a silver-bullet treatment or vaccine, we are protecting more of our patients through a host of small changes."
While the NYU study only looked at about 5,000 cases in a single health system in New York, another analysis by Bilal Mateen, a researcher at the Alan Turing Institute in the United Kingdom similarly found that the death rate has fallen about 20 percentage points since the pandemic began.
The study, which was released as a preprint before it is set to appear in the journal Critical Care Medicine, looked at data from more than 20,000 hospitalizations in the UK.
"This trend remains after adjustment for patient demographics and comorbidities suggesting this improvement is not due to changing patient characteristics," the analysis said. "Possible causes include the introduction of effective treatments as part of clinical trials and a falling critical care burden."
To be clear, the death rate is "still higher than many infectious diseases, including the flu," Horwitz told NPR. And many patients still have severe symptoms months after first testing positive. "It still has the potential to be very harmful in terms of long-term consequences for many people," she said.
Horwitz acknowledged that "people who are getting hospitalized now tend to be younger" and have fewer health conditions but even when adjusted for age and other diseases, the study found that the death rate among older patients has dropped by about 18 percentage points.
"Clearly, there's been something [that's] gone on that's improved the risk of individuals who go into these settings with COVID-19," Mateen told the outlet.
Doctors who were not involved in the studies agreed that there were numerous reasons for the drop.
Khalilah Gates, a critical care pulmonologist at Northwestern Memorial Hospital in Chicago, told NPR that patients in the early days of the pandemic were put on ventilators and breathing machines and perhaps offered enrollment into critical trials but "six-plus months into this, we kind of have a rhythm, and so it has become an everyday standard patient for us at this point in time."
Amesh Adalja, an infectious disease expert and emergency medicine physician at the Johns Hopkins Center for Health Security, added that doctors have also learned to quickly identify patients at risk of blood clots or "cytokine storms," when the body's immune system attacks itself.
"We know that when people are getting standardized treatment, it makes it much easier to deal with the complications that occur because you already have protocols in place," he said. "And that's definitely what's happened in many hospitals around the country."
Mateen stressed that hospital capacity has been key in reducing the death rate in the UK because when "staff are stretched, mistakes are made."
"It's night and day to take care of someone with a disease you've never seen before, than taking care of someone where you've seen hundreds," Horwitz told The Wall Street Journal. "It's also probably that the hospitals are not overwhelmed, but that can change."
Indeed, the number of new cases in the United States hit a record high of more than 77,000 on Thursday and hospitalizations hit record highs in numerous states like Ohio, Iowa, Utah, and Oklahoma. Hospitals in Utah, Wisconsin, Idaho, and others are already nearing full capacity.
As hospitals in hot spots are stretched thin, Horwitz stressed that wearing a mask could mean the difference between life and death.
A study by researchers at the University of California, San Francisco and Johns Hopkins Bloomberg School of Public Health published in the Journal of General Internal Medicine found that masks may reduce the amount of the virus the wearer is exposed to, "leading to higher rates of mild or asymptomatic infection."
"Masks, depending on the material and design, filter out a majority of viral particles, but not all," the study said. The researchers found that in some cases, "if 80% of the population wears a moderately effective mask, nearly half of the projected deaths over the next two months could be prevented."
Countries that had high levels of mask-wearing before the pandemic have fared better than other nations and subsequent resurgences have been less deadly.
"The more virus you get into your body, the more sick you are likely to get," said study co-author Monica Gandhi, an infectious disease expert at UCSF.
"Masks can prevent many infections altogether, as was seen in health care workers when we moved to universal masking. We're also saying that masks, which filter out a majority of viral particles, can lead to a less severe infection if you do get one," said Gandhi. "If you get infected, but have no symptoms – that's the best way you can ever get a virus."
The study compared outbreaks on two cruise ships in the winter. In February, 18% of 634 people who tested positive aboard the Diamond Princess cruise ship in Japan were asymptomatic. But a cruise ship in Argentina, where workers handed out surgical masks to all passengers and N95 masks to all staff after the first passenger tested positive, had an 81% asymptomatic rate among 128 people who tested positive.
Likewise, as hundreds of food processing plant workers died from the coronavirus, plants that distributed masks to workers saw high asymptomatic rates. A seafood processing plant in Oregon and a Tyson chicken processing plant in Arkansas had 95% asymptomatic rates among hundreds of infections after giving workers masks.
Gandhi said that public health agencies like the Centers for Disease Control and Prevention should stress these findings along with the current messaging that wearing a mask prevents asymptomatic people from spreading the virus to others.
"We messaged that mask wearing will protect other people, and that did not seem to convince our country as much as we would have hoped," she said. "If you think something's going to help you or your family, you are going to do it more than if you think you're helping others."