Timeline for COVID: Contagious Period, Quarantine, Testing and More



Although there are many different COVID-19 tests available, they can generally be broken down into two types: molecular and antigen tests.

Molecular tests include nucleic acid amplification tests (NAAT) such as polymerase chain reaction tests (RT-PCR or PCR tests). They’re usually processed in a laboratory and are generally more accurate than antigen tests, but results can take longer.

At-home rapid tests are antigen tests, which use a different mechanism to detect infection. These tests can be processed right in your home using a kit that looks similar to an at-home pregnancy test and gives results within 10-15 minutes.

Antigen tests are still fairly accurate, particularly when someone is experiencing symptoms and their viral load is very high. However, they can be less accurate when someone has a lower viral load, such as in someone without symptoms. This could lead to false negative test results.
You may consider doing COVID-19 testing ahead of time as another level of precaution before holiday gatherings. If possible, taking an at-home rapid COVID-19 test the day of the event is ideal.
While these tests aren’t 100% accurate, a negative result strongly suggests that you’re not contagious at that particular time.

It’s important to understand the limitations of the test — there’s a possibility for a false negative test, especially if you test too early after a possible exposure. The Centers for Disease Control and Prevention (CDC) recommends testing 5-7 days after your last exposure, if you’re fully vaccinated.
Serial testing — meaning repeating the test several days earlier before the actual gathering — can help improve accuracy of your results. Test can cost as much as $20 to $40 a test.
Home tests will miss some infections and in rare cases mistakenly indicate an infection. One popular test misses around 15 out of 100 infections — these are called “false negatives” — and gives a false positive result in about 1 in 100 people who aren’t infected.



“Even on the unlikely event [those tested] actually have COVID and don’t know it, they are unlikely to have COVID at a level that they’re going to spread it,” she said during a Facebook Live Tuesday.
That said, those with symptoms and known exposure to COVID should opt to stay home from gatherings, she added.

“If somebody still got really bad COVID symptoms and they’ve had an exposure like that should, you know, you shouldn’t gather,” she said.

According to Dr. Nimmi Rajagopal, the associate chair of the Department of Family and Community Medicine for Cook County Health, the accuracy of the test “depends on the scenario.”
“There are, of course, with any tests, there’s a ratio of you can get false positives or false negatives and these tests fall in that same realm,” she told NBC Chicago last month. “So it kind of depends on what you’re testing for and what the risk is.”

“So if someone is having symptoms and they get a negative test, one, it depends on the severity right? If you’re having severe symptoms we don’t want you to just do a home test either,” she said. “We want you to call your doctor’s office and make sure that they have an opinion here because there are of course other things like the flu that are out there that can mimic symptoms or have similar symptoms. But if you’re having symptoms and they’re kind of mild and lingering and you use the test and it’s negative, we want you to take the precautions and then retest in three to five days. And that’s why most of these kits actually come with two tests.”

That said, those with symptoms and known exposure to COVID should opt to stay home from gatherings, she added.

“Nothing is 100% but a combination of a fully vaccinated, boosted and then even on top of it, if you want another level of protection, tested gathering is really the best thing that we have in terms of helping to keep setting as safe as they can be,” she said, adding that the at-home tests are “quite reliable and I encourage people to use them.”

Here are the Covid 19 symptoms as I understand it:
Symptoms may appear 2-14 days after exposure to the virus. People with these symptoms may have COVID-19:Fever or chillsCoughShortness of breath or difficulty breathingFatigueMuscle or body achesHeadacheNew loss of taste or smellSore throatCongestion or runny noseNausea or vomitingDiarrhea

The symptoms for Delta are similar to Covid 19:
What is the difference between the original COVID-19 virus and the Delta variant?
The Delta variant causes more infections and spreads faster than the original SARS-CoV-2 strain of the virus that cause COVID-19. Vaccines remain the best way to reduce your risk of severe illness, hospitalization, and death from COVID-19.

Dr. Sam Elgawly, director of clinical excellence at Inova System, a health care company in Virginia, recently told WJLA in Washington that there aren’t major differences.

* “I think the simplest answer to the question, honestly, is that there aren’t many actual differences between delta and omicron for the most part,” said Elgawly.Antigen tests are still fairly accurate, particularly when someone is experiencing symptoms and their viral load is very high.
Dr. Katherine Poehling, an infectious disease specialist and member of the Advisory Committee on Immunization Practices, told NBC News last week that a cough, congestion, runny nose and fatigue appear to be prominent symptoms with the omicron variant. But unlike delta, many patients are not losing their taste or smell.

Since COVID-19 is transmitted through contact with respiratory fluids carrying the infectious SARS-CoV-2 virus, a person can be exposed by an infected person coughing or speaking near them.
When you’re outside, fresh air is constantly moving, dispersing these droplets.

Look for emergency warning signs for COVID-19. If someone is showing any of these signs, seek emergency medical care immediately:Trouble breathingPersistent pain or pressure in the chestNew confusionInability to wake or stay awakePale, gray, or blue-colored skin, lips, or nail beds, depending on skin tone

Typically, vaccinated people are either asymptomatic or have very mild symptoms if they contract the Delta variant. Their symptoms are more like those of a common cold, such as cough, fever or headache, with the addition of significant loss of smell.

Rapid tests, detect molecules that are found on the virus’s surface, called antigens. They’re not as accurate, but they can be run at home and provide results in as little as 15 minutes.
The tests themselves are most accurate when a person has symptoms, studies suggest. While they are able to detect asymptomatic cases, there’s a greater likelihood for false negatives. Most experts agree that people get positive antigen results when they’re most contagious.
If the course of an infection resembles a bell curve on a chart, a PCR test is good at detecting the infection all the way through. A rapid antigen test is best at detecting within the hump of that curve, when a person is most infectious and poses the biggest risk to others.

“It takes more virus for the antigen test to be positive than it does for the PCR to be positive,” said Dr. Omai Garner, the director of clinical microbiology at UCLA Health, where he runs a testing lab. “That implies that you are more infectious if you are antigen-tested-positive.”

Garner said people need to be aware that while they may have runny noses or coughs but negative antigen tests, they should perhaps test themselves again a day or two later.
“These tests don’t seem to work really well in the early parts of these infections because it doesn’t look like omicron has as high a viral load in the first couple of days, as opposed to delta, which had a screaming-high viral load on Day One,” he said. “What is shifting now is, when did you get tested? Because there now appears to be a lower amount of virus early on, that might explain why the antigen tests are not showing up positive until Day Three, when there’s lots of positivity.”
Specifics about the reimbursement model are still unclear, however, and some experts have criticized the effort, as the program still carries an upfront cost. Testing kits that provide one to two tests are $14 to $25 at most official retailers. The price can shoot much higher at unofficial sellers.

Some concerning new wrinkles regarding antigen tests’ sensitivity are still being investigated, particularly as anecdotes about false negative results from rapid tests are on the rise.
The FDA said Tuesday that it was monitoring and evaluating antigen tests on the market for their sensitivity to the omicron variant, and it said preliminary data appeared to show a decline in receptivity.

“Early data suggests that antigen tests do detect the omicron variant but may have reduced sensitivity,” it wrote.
The potential is concerning, but the FDA did write that the findings were preliminary and added that it was “continuing to further evaluate the performance of antigen tests using patient samples with live virus.”