Over the last month, 19 children in a care home in New Jersey have fallen ill with adenovirus infections. Seven of those children have died, and it’s possible that more cases will be confirmed. The investigation into the causes of the outbreak, and the reasons for the extent of it, is ongoing.

The Wanaque Center for Nursing and Rehabilitation in Haskell, New Jersey, provides long-term care for “medically fragile children,” including children in comas or on ventilators. Although adenoviruses usually only cause mild illnesses like common colds or pink eye, they can have more serious effects in people who already have other conditions, which is probably why the viruses have been so fatal in this instance.

“Unfortunately, the particular strain of adenovirus (#7) in this outbreak is affecting medically fragile children with severely compromised immune systems,” said New Jersey Health Commissioner Shereef Elnahal in a public statement. “The strain has been particularly associated with disease in communal living arrangements and can be more severe.”

Because the virus is able to survive for long periods outside hosts or bodies of water, the CDC recommends “strictly follow[ing] infection-control practices” like hand-washing and surface disinfecting to prevent adenovirus infections. An inspection at the Wanaque Center on Sunday found “minor hand-washing deficiencies,” said Dr. Elnahal. “The facility has been instructed not to admit any new patients until the outbreak ends... and the Health Department is continuing to work closely with the facility on infection control issues.”

Nurses at the facility have “reported a shortage of nursing staff which may lead to poor infection-control practices that can put patient safety at risk,” according to a statement by Debbie White, president of the health care labor union HPAE. “Staff have urged the center’s administrators to provide enough protective gowns, gloves, and masks.” Infection-control issues were also noted at the center in 2017 and 2016.

Not the viral apocalypse, but wash your hands

“Adenovirus” is not one simple thing. In humans alone, there are seven species, which together include more than 60 different types of virus. Further types can infect other species.

Adenoviruses have been extensively studied, in part because they are able to carry a lot of genetic information and they’re particularly useful for gene therapy research: the genetic material that makes them able to replicate and cause infections is removed, and instead they’re used to carry useful genetic information into a host cell.

The different types of adenovirus can cause a range of illnesses in humans. Some cause gastroenteritis or bladder infections while others cause conjunctivitis (pinkeye). Many cause sore throats, colds, fever, and slightly more serious illnesses like bronchitis. It’s only in rare cases that they lead to severe conditions like pneumonia, mainly in people whose immune systems are compromised or who already have respiratory or cardiac illnesses.

Adenoviruses spread in the usual ways, through coughing, sneezing, and lurking on infected surfaces. They can also be transmitted in swimming pools that don’t have enough chlorine in them. That means the usual tactics for preventing infection—wash your hands, cover your mouth, don’t share drinks—apply here, too. Although there is a vaccine for two adenovirus types, it’s currently only available to the military. For most infections, over-the-counter remedies are enough to handle the symptoms while the immune system does its job.

It’s pretty important to get context on the seven deaths recorded so far in New Jersey. Influenza, for which there is a vaccine available, claims far more lives than adenovirus infections. In the current influenza season, the CDC has recorded 183 children who died from flu. That’s a reasonably high tally—in the 2011-2012 season, it was 37 children. In the pandemic year of 2009, it was 358.

Because flu deaths in adults aren’t all reported to the CDC, there aren’t such precise figures, but estimates for total flu deaths in 2011-2012 are around 12,000. The following year, the estimate was 56,000 people. And of course, many more people were hospitalized. Adenovirus outbreaks severe enough to lead to hospitalization or death are, by comparison, extremely rare. Although the outbreak in New Jersey is tragic for the children and their families, there's no need to be especially concerned about it spreading.