Postal mail poses minimal risk for transmitting COVID-19.
As of 21 March 2020, there is no data on the transmission of SARS-CoV-2 through postal mail. Experts tell us that the risk of contracting SARS-CoV-2, the virus that causes COVID-19, seems to be low.
A study published in the New England Journal of Medicine on 17 March 2020 found that
On cardboard, no viable SARS-CoV-2 was measured after 24 hours
Viable virus was detected up to 72 hours after application to [plastic and stainless steel]
The plastic used in the NEJM study was polypropylene.
The varnish on magazines and commercial postcards can include ingredients such as plastics, resins, or waxes. The Anonymous Postcard Project uses a coated polyester film laminate. There is no data yet on the viability of the virus over time on any of these materials.
The US Centers for Disease Control and Prevention (CDC) FAQ states
there is likely very low risk of spread from products or packaging that are shipped over a period of days or weeks at ambient temperatures
The World Heath Organisation (WHO) Q&A provides similar guidance.
An article in USA Today on 21 March 2020 states:
Joseph Vinetz, a professor of medicine at Yale and infectious disease researcher, said that wiping down mail may help with some people’s anxiety, but there’s no evidence that doing so would be useful to protect against coronavirus.
and
Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security, agreed that the risk is theoretical and minimal.
“I will never disinfect my mail,” he said. “And I donโt even know how you would disinfect your mail.”
An article on NBC Today on 20 March 2020 offers a similar message:
Dr. Joseph Vinetz, an infectious disease doctor at Yale Medicine in Connecticut, said people don’t need to take any special precautions while opening mail.
He wasnโt worried about the public handling letters, USPS parcels or Amazon packages as long as they kept up their hand hygiene.
References
US Centers for Disease Control and Prevention (CDC) Coronavirus Disease 2019 (COVID-19) Frequently Asked Questions
World Health Organisation (WHO) Q&A on coronaviruses (COVID-19)
“Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1” New England Journal of Medicine, 17 March 2020
“Can you get coronavirus by opening your mail?โ NBC Today, 19 March 2020
“Send Love to someone special with free An Post Postcards” An Post Press release 20 March 2020
“Coronavirus can live on surfaces for days. But it can’t travel through the mail, experts say” USA Today, 21 March 2020