If you are tested for Covid-19 before reuniting with family and friends during the holiday season, even if your result is negative, you may not actually be in a clear place.
Given that a negative Covid-19 test has become a ticket to skip quarantine when traveling across many government lines, it’s easy to believe that a negative test means you don’t have a risk of carrying the virus.
But the reality is much more complicated. A negative test does not mean that you do not carry the virus, but rather that you did not have the virus during a particular snapshot, experts say. Covid-19 tests are not sensitive enough to detect traces of the virus on the day after someone is infected, and can sometimes take more than a week to test for the virus after infection.
Amanda Simanek, an associate professor of epidemiology at the University of Wisconsin-Milwaukee and a member of the Reputable Pandemic, a public health campaign on social media run by a cohort of female experts in public health and economics, spoke to the Guardian about basic things people need to do. you know when you rely on testing as a strategy to prevent the spread of Covid-19.
You may be tested too early
Covid-19 has an incubation period of between two and 14 days. About half of people who contract Covid-19 will develop symptoms within five days of exposure. But for some people, this can take up to two weeks.
“If until the day you were tested, or even a few days before you were tested, you simply continued to live a normal life and did not take other precautions to prevent exposure to Covid-19, this negative test really tells you you have no detectable virus that day, ”Simanek said.
“You may be exposed, tested on day two or three after that exposure, be negative, and then develop symptoms on day eight.”
Symanek quoted fellow public health expert Megan Rani, a Rhode Island-based doctor and researcher, who compared the sensitivity of Covid-19 to that of a pregnancy test. “Just as a pregnancy test cannot replace birth control, Covid-19 tests should not be seen as a substitute for solid strategies to reduce community transmission,” Rani wrote in a statement to NBC News.
This does not mean that you should avoid testing, but it does mean that testing alone cannot guarantee that you will not transmit the virus. The Covid-19 test, done after five days of quarantine, is much more informative about whether you have the virus than one taken without quarantine. “Then you know that there is a certain date on which the last known exposure may have occurred,” Simanek said.
How your quarantine matters
If you want your Covid-19 test to be useful, you need to take quarantine seriously.
This means that you should avoid the grocery store and choose to deliver your groceries. Parents of children who go to school during quarantine are not technically quarantined. You or someone in your household should not communicate in person with anyone outside your household. “This does not mean executing orders, but avoiding everything else,” Simanek said.
If you are traveling, this means that you should not make contact with people traveling to your destination. Planes, buses and trains are no exception.
“You need to isolate yourself from others, just do what you can to exclude any exposure.”
Symanek acknowledges that there are logistical challenges in conducting such a strict quarantine. “This is a challenge for families who cannot work from home or whose children go to school in person or take care of children because they themselves are the main worker.”
But this type of quarantine is the best way to ensure that a negative test is not fake.
Testing is most informative on a larger rather than individual scale
Covid-19 tests are most useful for community-based action and monitoring the spread of the virus on a large scale.
Several countries have allowed travelers to bypass a certain quarantine period for people who have tested negative for the virus, usually no more than 72 hours before arrival. While this may be useful for civil servants trying to mitigate the spread on a larger scale, the same strategy is not as useful at the individual level.
“Testing is a vital component of a broader strategy for the content of Covid-19 in your community,” Simanek said. But for people who want to visit the family, the negative test “is not very informative and does not necessarily change the course of action you should take.”
“If you’re talking about visiting grandparents, you don’t know if you’re at that 50% [of people] who develop symptoms by the fifth day. Taking a negative test and accepting that you are clean is a risk that you will pass on to your family members. This is a risk I would not take personally. “
Bottom line: Tested negative? You still need to practice other safety precautions
This does not mean that you should cancel all holiday plans, but emphasizes the need for additional safety measures if you see at risk family and friends, even if you get a negative test and especially if you have not properly quarantined against the background of potential exposure.
According to the Centers for Disease Control and Prevention (CDC) guidelines, outdoor celebrations are much safer than indoor ones, where the virus is most likely to spread. Masks and social distancing are essential. When eating, try to stay away from each other and use separate utensils.
Or have a virtual gathering, a guaranteed risk-free way to celebrate the holidays.
“The nature of this virus is that you can have it and you don’t know it yet, you don’t have symptoms, [but] you can pass it on to other people, ”Simanek said. “We all have to accept that we have been exposed and act accordingly.”