The coronavirus (SARS-CoV-2) is much smaller than the wavelength of visible light and, therefore, has no intrinsic color. It is essentially transparent to the human eye, even when viewed with an optical microscope.
SARS-CoV-2 particles can be between 50 and 140 nanometers across, or roughly 1,500 to 500 times smaller than the width of a human hair. These images were created using scanning electron microscopy.
If you see any line on your COVID test, err on the side of caution and take precautions to avoid spreading the virus to others. While a dark line that shows up quickly is a sign that there's more virus in your body, even a faint line can be positive (and may turn darker if you test again in the coming days). Katella K.
Currently, the dominant variant nationwide is XFG, with 61% of cases, followed by XFG.14.1, with 15% of cases, and XFG.1, with 5% of cases. "The original omicron variant is gone now," says Dr. Rupp. "Currently subvariants of omicron are circulating, including XFV, NW.1 and XFZ."
Overview. Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus. Most people infected with the virus will experience mild to moderate respiratory illness and recover without requiring special treatment.
Subclade K is a newly emerged subgroup of a well-established human seasonal flu virus called H3N2 influenza A virus. So far, there's no evidence from laboratory or population studies that this strain can bypass existing immunity from past influenza infections or vaccines.
We are still learning how long different symptoms of Long COVID can last, and our understanding of the condition continues to evolve. For some, Long COVID symptoms may last three months after an infection, while for others, symptoms can continue even longer — sometimes for years. Everyone's experience is different.
One of the most talked-about emerging strains this year is the NB.1.8.1 variant, part of the Omicron family. While current evidence suggests it is not more severe than previous variants, it is spreading quickly and causing concern due to its highly contagious nature.
Doing the test
In short, coronavirus is a type of virus that causes the disease known as COVID-19.
"If you see a test line, it means that there are the viral nuclear protein antigens in your specimen, which is supposed to be interpreted as a positive test result," he said. A positive result: Two lines on control (C) and test (T). Negative: One line on control (C).
They can degrade. Just like food in your cabinet has an expiration date, the tests have an expiration date.” Dr. Rhoads said if a person uses an expired COVID test, they risk getting a “false negative” even if they are actually sick.
“A faint line is a positive test result,” says infectious disease expert Amesh Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security. Thomas Russo, MD, a professor and chief of infectious diseases at the University at Buffalo in New York, agrees.
Coronavirus virions are spherical or variable in shape and composed of an outer layer of lipid covered with a crown of club-shaped peplomers or spikes. Within each spike is a helical single-stranded RNA-containing structural protein.
Symptom check: Is it COVID-19 or a cold? COVID-19 symptoms usually start 2 to 14 days after exposure to SARS-CoV-2. But symptoms of a common cold usually appear 1 to 3 days after exposure to a cold-causing virus. There's no cure for the common cold.
The COVID virus has more success surviving on hard surfaces, such as glass and plastic, than on porous ones like bedding. Once the virus lands on a porous material like a fabric, the droplets evaporate much quicker than they do on a hard surface.
a high temperature – you may feel hot, cold or shivery, or your skin is hot to touch on your chest or back (you do not need to measure your temperature) a new, continuous cough – this means coughing a lot for more than an hour, or 3 or more coughing episodes in 24 hours. a loss or change to your sense of smell or taste.
PCR tests are accurate nearly 99% of the time. Antigen tests don't pick up all COVID-19 infections, but timing is also important. People sometimes test negative because they take the rapid at-home test too soon during the course of their illness.
Taking Care of Yourself at Home
Older adults are at highest risk of getting very sick from COVID-19. More than 81% of COVID-19 deaths occur in people over age 65. The number of deaths among people over age 65 is 97 times higher than among people ages 18-29 years.
Compared with flu, COVID-19 can cause more severe illness in some people. Compared to people infected with influenza virus, people infected with SARS-CoV-2 may take longer to show symptoms and may be contagious for longer periods of time.
Ultimately, long COVID is a chronic condition that can significantly affect quality of life, mental wellbeing and overall health. While long COVID is not usually immediately or directly life-threatening, it's possible it could exacerbate existing conditions, and play a role in a person's death in this way.
Since August 24, 2025, a total of 33,059 COVID-19 detections have been reported (from 434,597 tests). A total of 25,497 laboratory-confirmed COVID-19 detections with age information have been reported. Individulas aged 65+ years reported the highest proportion of all detections (59%) (Figure 5).
We now know that, unfortunately, COVID can damage the brain in many ways. When people first become sick from the virus, they may develop encephalitis — inflammation of the brain — causing confusion, difficulty concentrating, and memory problems.