You’ve probably experienced it at some point during the covid pandemic: you get sick with all the symptoms of the virus but always test negative.
Then about a week later, you get worse and feel even sicker and, perhaps miraculously, a test comes back positive.
The phenomenon, dubbed ‘pre-Covid’, is taking hold again amid a new uptick in virus infections.
One theory is that the period of symptoms before testing positive is caused by someone contracting a mild bug or other virus, leaving their iImmune system more vulnerable to a Covid infection.
Another is that it is simply the early stages of a Covid infection, known as the incubation period, and the amount of virus in the body is too low to be detected by a test.
People can have Covid but not test positive for the virus, scientists say (file image)
Dozens of people have shared their experiences with ‘pre-Covid’ on social networks, another from Alaska wrote: ‘I’m pretty sure I have Covid, but I keep testing negative…’
They added: ‘The person I live with has it and I’m definitely sick, I just tested negative. I don’t know if I should continue to quarantine with her or not.”
A third person from Canada said: ‘I think he might be sick. However, rapid tests are coming back negative.
“The most frequent symptom is that my sinuses hurt and my nose goes back and forth from stuffy to runny. I am sneezing a lot and feel very confused.
Scientists say covid cases are now on the rise, likely fueled by the new EG.5 or ‘Eris’ variant, which is now behind one in five infections in the US.
Hospitalizations are also up 60 percent from a record low last month, and 14 percent in one week, but are still well below levels even in January of this year.
However, people suffering from flu-like symptoms who test negative for Covid could also have other illnesses, such as the common cold.
Explaining the pre-Covid phenomenon, Dr Stuart Fischer, an emergency medicine expert in New York City, told DailyMail.com: ‘The symptoms people relate to may be their immune response to Covid (triggered ) from past exposure or vaccination.
‘When someone is vaccinated, this stimulates their immune response in a way that would become memory.
“In other words, if the person were exposed again, the body would remember what to do and release chemicals to fight the infection.”
Asked how long this phase could last before someone tests positive for covid, he said it would be no more than a couple of days.
Dr. Fischer added that it was also possible for someone to have the symptoms, have covid, but never actually test positive.
He said this was because the immune system would kick in and kill the virus before it had a chance to take hold.
Dr. Thomas Moore, an infectious disease expert at the University of Kansas, said: “It takes a while for the virus to be shed in sufficient numbers to be detectable.”
If you have symptoms and the test is negative initially, you should retest 48 hours later. The chance of a positive test increases significantly every other day.
He added: ‘There are also cases where patients are convinced they have Covid or are concerned they have Covid and get tested repeatedly but get a negative result because they don’t.
“But if they continue testing, it is possible that they will eventually test positive because they coincidentally contracted the virus along the way.”
Dr. Moore also said that people are likely to show up for a covid test faster than before in the pandemic because they are now more aware of the symptoms.

The above shows how EG.5 is growing in the US and has already become the most dominant variant of the virus behind nearly one in five infections.

Covid hospitalizations are up 40 percent from their all-time lows recorded last month, but are still well below levels prior to the pandemic.

Covid deaths continue to fall, Centers for Disease Control and Prevention statistics show
It is also possible that the symptoms are due to other infections, such as the common cold, which trigger symptoms similar to those of Covid.
Symptoms someone could suffer from during the ‘pre-Covid’ stage include headaches, according to a study 2020.
He added: “All diseases exist in a subclinical form, whether it’s pneumonia, toothache, gout, hypertension, we all have a very mild version that is possibly short-lived with symptoms that are too weak to recognize.”
“A person can recognize that something is vaguely wrong, but by the time they get to the doctor it has subsided.”
Lateral flow Covid tests are still sold in most pharmacies for people to check if they have the virus, while PCR tests can be ordered online.
The CDC says that people who have symptoms of covid or who have been around someone who has tested positive for covid should also get tested for the virus.
But there is no requirement to self-isolate if you test positive, since the CDC relaxed these rules in August of last year.
They said at the time that conditions were “very different” than at the start of the pandemic.