Close to 10,000 people have contracted the new coronavirus that originated in Wuhan, China—more cases than SARS in 2003. So far, 213 people have died. The preliminary fatality rate for 2019-nCoV hovers around 3%—which is low, but still concerning because of the number of cases accumulating.
But that fatality rate is likely to be higher in older adults. Unofficial open-source data from researchers based in the UK and China show that out of 41 deaths, 39 were in people over 50. Bloomberg reports similar figures. While that’s not unexpected, it indicates the need for effective therapies targeted at this population. And as the proportion of adults over 50 continues to increase globally, future pandemics could be deadlier than they’ve been in the past.
“During the original SARS outbreak, we found that the fatality rate was 10%,” says Vineet Menachery, an immunologist at the University of Texas Medical Branch who studies how coronaviruses affect aging immune systems. “But that jumped to 50% in people over the age of 50.” There was a similar pattern of fatalities with MERS in 2015.
All three viruses—SARS, MERS, and now 2019-nCoV—fall within the category of coronaviruses, which get their names from the spiky crown of proteins on the viruses’ outer shell. So while we don’t have a firm fatality rate for older adults with 2019-nCoV, it’s likely that it’ll also be higher than in younger adults.
There are two reasons older adults are more susceptible to infections. First, seniors are more likely to have other chronic health conditions, like diabetes or chronic obstructive pulmonary disease, that make it harder for their bodies to cope with damage caused by a new pathogen. Every year, the majority of flu deaths are seen in people 65 or older.
Second, the immune system changes with age—particularly in its ability to respond to coronaviruses. Unlike the flu virus, which does most of the damage to your body on its own, most of the symptoms from coronavirus infections actually come from the body’s immune response, Menachery says. Although he and his lab team are still characterizing these reactions, it seems like coronaviruses encourage older immune systems to kick in with extra inflammation, which can have a cascading effect.
These downstream effects can be particularly acute when the virus lives and reproduces exclusively in a vital organ like the lungs—which SARS, MERS, and 2019-nCoV all do. In an effort to control the infection, the body will wall off portions of the lung that are harboring most of the infection. These sections are then not available to take in oxygen. “You can still breathe, but not with the same capacity. If you have COPD and heart disease, you have less capacity to begin with,” Menachery says, which ultimately makes the infection more likely to be fatal.
Unlike the flu, which has higher fatality rates in both young children and older adults, coronaviruses tend to only be more dangerous for seniors. In a paper published on Jan. 29, scientists writing in the New England Journal of Medicine recorded 0 cases of 2019-nCoV in children 15 and under. This doesn’t mean that children are immune to the virus, but they may be better at fighting it off if they’re otherwise healthy.
As people live to older ages and constitute a bigger part of the global population, we’ll need better health interventions to protect them specifically, Menachery says. This will be a unique challenge for scientists developing vaccines and treatments for 2019-nCoV; it’s hard to model aging because animals like mice don’t age the same way that humans do.
Right now, it’s critical that scientists develop treatments appropriate for older adults affected by 2019-nCoV, who are at the highest risk of complications. But seniors will have to be at the front of public health officials’ minds as they prepare for future pandemics, too. The more humans press into animal territory through farming, urbanization, and deforestation, the more likely it is that a virus present in animals will mutate to be transmissible in humans, just like 2019-nCoV likely did. “Will we have another coronavirus in the next 10 years?” Menachery asked rhetorically. “At this point, I’d have to say yes.”
Update: This story was updated on Jan. 31 with current infection and death figures.