...A negative test isn't enough to have a safe holiday. Here's why.
More frequent Covid-19 testing is one key to help end the pandemic. But as individuals, we can't rely on testing alone to protect ourselves and others.
Take this recent example: Public health officials in New Zealand reported on a cluster of cases that likely spread aboard a long-haul flight. Yet the suspected index cases -- the people who likely spread the virus to others -- tested negative for the virus a couple of days before boarding their plane in Switzerland and thought they weren't infected.
This goes to show: A negative test is not an all-clear in terms of being able to safely interact with others without masks or other precautions. "Testing negative is not like a passport for people to go out and do whatever they want to do," as Muge Cevik, a virologist and physician at the University of St. Andrews, told me earlier this fall.
As people make (unwise) plans to travel this Thanksgiving week, they should understand that testing negative does not mean it's safe to be in close contact with other people. It does not mean it's safe to take masks off.
Scientists don't yet know exactly when a person who is infected with the coronavirus will start testing positive for the virus. There are situations when a person could test negative, be infected, and also be contagious. It's also possible -- since the virus multiplies itself exponentially in the body very quickly -- that someone could test negative in the morning (and not be contagious), but by the afternoon test positive (and be very contagious). ...