You’ve Got Mail. Will You Get the Coronavirus?

The practice of disinfecting mail dates back to the invention of quarantine. There’s little evidence it needs to be invoked today.

You’ve Got Mail. Will You Get the Coronavirus?
A mail carrier in Manhattan on Monday.Credit...Jordan Gale for The New York Times

Scientists agree that the main means by which the SARS-CoV-2 virus jumps from an infected person to its next host is by hitching a ride in the tiny droplets that are sprayed into the air with each cough or sneeze. But with deliveries now at holiday levels as locked-down Americans shop online rather than in person, the question remains: Can you catch the coronavirus from the parcels and packages your overburdened mail carrier keeps leaving at your door?

The first formal process for curbing the spread of infection by detaining travelers from an affected region until their health was proved was instituted in what is now Dubrovnik, Croatia, in 1377, against the bubonic plague. (This temporal buffer was originally 30 days, but when that proved too short, it was extended to 40 days, or quaranta giorni, from which we derive the word “quarantine.”)

Mail disinfection soon followed, as the then Republic of Venice extended and formalized the quarantine process to include cargo. Items that were considered particularly susceptible, including textiles and letters, were also subject to fumigation: dipped in or sprinkled with vinegar, then often exposed to smoke from aromatic substances, from rosemary to, in later years, chlorine. Once the items were treated, a distinctive wax seal or cancellation was usually applied to them, so the recipient would know where and when the disinfection had been carried out. (Such marks often provide the only remaining evidence of the ebb and flow of disease; some minor outbreaks of plague or typhus in remote areas of medieval Europe, for example, would have been lost to history without their postal traces.)

The diseases changed, but for centuries mail disinfection techniques remained largely the same. As recently as 1900, during a plague outbreak in Honolulu, letters were routinely disinfected by clipping off the two opposite corners of each envelope and then spreading a batch of mail out in an airtight room filled with sulfur fumes for three hours.

A representative for the U.S. Postal Service was unwilling to discuss current sanitization protocols. But the agency’s website reports that the only mail items receiving treatment are letters and parcels sent to ZIP codes beginning in 202, 203, 204 and 205, which serve federal government agencies in Washington, D.C. In a process that began shortly after the 2001 anthrax attacks, the Postal Service sends mail destined for those ZIP codes to New Jersey, where they are put on a conveyor belt and passed under a high-energy beam of ionizing radiation that kills bacteria and viruses. The letters and packages are then “aired out” for a while, before being forwarded to their destinations. The paper is left slightly faded and somewhat crispy, but sterile.

Should mail irradiation be extended beyond these exclusive ZIP codes, to help prevent the spread of the coronavirus? On CBS News’s Face the Nation on Sunday morning, Scott Gottlieb, the former commissioner of the Food and Drug Administration, warned that SARS-CoV-2 could potentially be transmitted by contaminated objects. “This is a sticky virus,” he said. The structure of the coronavirus’s protective envelope helps it bond tightly to certain surfaces: skin in particular, as well as fabric and wood, but also plastic and steel.

Some government agencies seem concerned that all of that circulating paper might be a potential vector. In early February, when COVID-19 was still just “the coronavirus” — and, for most Americans, still someone else’s problem — China’s central bank announced that it would quarantine the country’s cash, to prevent the disease from spreading from one person to another on money. The government collected bank notes from Hubei, the worst-hit province, and then sanitized the stacks of bills, either by baking them at a high temperature or bathing them in ultraviolet rays. The newly laundered cash was then kept in isolation for seven to 14 days before being rereleased into the banking system.

A few weeks later, the U.S. Federal Reserve began quarantining dollar bills repatriated from Asia, holding them for seven to 10 days before allowing them to re-enter the domestic financial system. Bank notes are made of cotton pulp, not wood fiber, but still: Why sanitize money and not mail?

Representatives of the big three package deliverers in the United States — U.P.S., FedEx and the Postal Service — insisted there is no need. “The C.D.C. has advised that there is a low risk of transmission on packages,” said Matthew O’Conner, a spokesman for U.P.S. FedEx, in a statement. “The guidance from the W.H.O. is that the likelihood of an infected person contaminating commercial goods is low, and the risk of catching the virus that causes COVID-19 from a package that has been moved, traveled, and exposed to different conditions and temperature is also low.”

David Partenheimer, a spokesman for the Postal Service, noted that the surgeon general, Dr. Jerome M. Adams, along with the Centers for Disease Control and the World Health Organization, has “indicated that there is currently no evidence that COVID-19 is being spread through the mail.”

This is because many scientists think it is quite unlikely that you can catch the coronavirus by touching a surface that has the virus on it and subsequently touching your own mouth or nose. (One review of scientific publications on the subject concluded that hand washing seems to cut the risk of respiratory infection by a mere 16 percent — but added that the studies examined were of poor quality and more research was urgently needed.)

The German Federal Institute for Risk Assessment — Germany’s equivalent of the F.D.A. — advises that while the virus could, theoretically, be transmitted through this kind of “smear” infection, as opposed to the standard “droplet” infection, there have been no known cases in which individuals have caught the coronavirus by touching a contaminated surface and then transferring the virus to their mouth or nose. Then again, contact transmission is notoriously difficult to study and document.

A paper published in the New England Journal of Medicine last week shed more light on the subject. A group of researchers from the National Institutes of Health, the C.D.C., Princeton University and the University of California, Los Angeles, misted virus particles into a rotating drum and studied how long the floating particles survived on various surfaces. They found that the SARS-CoV-2 virus survived for up to 24 hours on cardboard — three times longer than its cousin, the original SARS.

“In that light, you might expect the virus to remain viable for hours but probably not days on mail,” said James Lloyd-Smith, one of the study’s authors. “But there are important caveats.”

Among these: The study specifically looked at aerosolized virus particles, rather than the fine droplets that infected people emit with each cough or sneeze. The line between aerosols and droplets is fuzzy, but, broadly, droplets are bigger and settle more quickly, while aerosols are smaller and float for longer.

“Little is known about the rate at which infected people generate such aerosolized viruses,” Dr. Lloyd-Smith said, although some medical procedures — including intubation to assist with breathing — are known to create aerosols. In addition, the experiment was designed to simulate indoor air; viruses like this one are expected to be stable for longer at lower temperatures and lower humidity.

In an experiment that might better mimic the effect of sneezing on a letter, researchers from Hong Kong University pipetted droplets of SARS-CoV-2 onto various surfaces. Their results, which have not yet been peer reviewed and do not include details on temperature and humidity conditions, found no infectious virus left on paper after three hours — although, alarmingly, a significant level could be detected on the outer layer of a surgical mask after seven days.

“The bottom line is that there is some hypothetical risk of viable viruses surviving on mail,” Dr. Lloyd-Smith said. “But given the time periods involved, this seems like a pretty minimal risk to the general public.”

Ben Chapman, a food safety specialist at North Carolina State University who studies the interaction of pathogens and surfaces, agreed that although the virus can persist on packages, these have not been identified as a risk factor for transmission. Nonetheless, he said, “I’d just wash my hands after handling,” rather than spray with Lysol or wipe with bleach. “I want to preserve the good sanitizers for risky things, and hand washing works just as well as spraying.”

For the delivery workers pulling 12-hour shifts to keep up with demand, and struggling to access the sanitizing supplies and hand-washing facilities they need, the situation is potentially riskier. “I would be more worried about the mail sorters and mail carriers, who are exposed to many more pieces of mail,” Dr. Lloyd-Smith said.

Delivery is deemed an “essential function” by the Department of Homeland Security, and the volume of packages is expected only to increase as more Americans are required to shelter in place. Irradiating all mail is both overkill and likely impossible, given the volumes in question and the resources required. But making sure that the people who are keeping mail moving during this pandemic are protected also seems essential, not to mention ethical.

“The safety and well-being of U.S. Postal Service employees and customers is our highest priority,” said Mr. Partenheimer, who added that the agency is closely monitoring the situation to implement C.D.C. and public health department advice.

  • Updated March 24, 2020

    • How does coronavirus spread?

      It seems to spread very easily from person to person, especially in homes, hospitals and other confined spaces. The pathogen can be carried on tiny respiratory droplets that fall as they are coughed or sneezed out. It may also be transmitted when we touch a contaminated surface and then touch our face.

    • Is there a vaccine yet?

      No. The first testing in humans of an experimental vaccine began in mid-March. Such rapid development of a potential vaccine is unprecedented, but even if it is proved safe and effective, it probably will not be available for 12 to18 months.

    • What makes this outbreak so different?

      Unlike the flu, there is no known treatment or vaccine, and little is known about this particular virus so far. It seems to be more lethal than the flu, but the numbers are still uncertain. And it hits the elderly and those with underlying conditions — not just those with respiratory diseases — particularly hard.

    • What should I do if I feel sick?

      If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.

    • How do I get tested?

      If you’re sick and you think you’ve been exposed to the new coronavirus, the C.D.C. recommends that you call your healthcare provider and explain your symptoms and fears. They will decide if you need to be tested. Keep in mind that there’s a chance — because of a lack of testing kits or because you’re asymptomatic, for instance — you won’t be able to get tested.

    • What if somebody in my family gets sick?

      If the family member doesn’t need hospitalization and can be cared for at home, you should help him or her with basic needs and monitor the symptoms, while also keeping as much distance as possible, according to guidelines issued by the C.D.C. If there’s space, the sick family member should stay in a separate room and use a separate bathroom. If masks are available, both the sick person and the caregiver should wear them when the caregiver enters the room. Make sure not to share any dishes or other household items and to regularly clean surfaces like counters, doorknobs, toilets and tables. Don’t forget to wash your hands frequently.

    • Should I wear a mask?

      No. Unless you’re already infected, or caring for someone who is, a face mask is not recommended. And stockpiling them will make it harder for nurses and other workers to access the resources they need to help on the front lines.

    • Should I stock up on groceries?

      Plan two weeks of meals if possible. But people should not hoard food or supplies. Despite the empty shelves, the supply chain remains strong. And remember to wipe the handle of the grocery cart with a disinfecting wipe and wash your hands as soon as you get home.

    • Can I go to the park?

      Yes, but make sure you keep six feet of distance between you and people who don’t live in your home. Even if you just hang out in a park, rather than go for a jog or a walk, getting some fresh air, and hopefully sunshine, is a good idea.

    • Should I pull my money from the markets?

      That’s not a good idea. Even if you’re retired, having a balanced portfolio of stocks and bonds so that your money keeps up with inflation, or even grows, makes sense. But retirees may want to think about having enough cash set aside for a year’s worth of living expenses and big payments needed over the next five years.

    • What should I do with my 401(k)?

      Watching your balance go up and down can be scary. You may be wondering if you should decrease your contributions — don’t! If your employer matches any part of your contributions, make sure you’re at least saving as much as you can to get that “free money.”

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