The vast majority of long haulers test negative for the virus. There's nothing specific to test for lasting coronavirus symptoms.
Post-acute COVID-19 is a syndrome characterized by the persistence of clinical symptoms beyond four weeks from the onset of acute symptoms. The Center for Disease Control (CDC) has formulated "post-Covid conditions" to describe health issues that persist more than four weeks after being infected with COVID-19
COVID-19 recovery. Post-COVID-19 symptoms, such as lingering cough, on and off fever, weakness, and changes to your senses of smell or taste, can persist for weeks or even months after you recover from acute illness. Persistent symptoms are sometimes known as long COVID-19.
Immunity is complicated and, yes, you can still get reinfected with COVID-19. In fact, a recent study found that unvaccinated adults were twice as likely to get reinfected with COVID-19 than those who got vaccinated after they'd recovered from their illness.
It is important to remember that some people with antibodies to SARS-CoV-2 may become infected after vaccination (vaccine breakthrough infection) or after recovering from a past infection (reinfected).
The most common symptoms are fever with a red rash, red eyes, red lips and red palms and soles. Abdominal pain, vomiting and diarrhea also occur. Half of the patients develop trouble breathing.