How long do symptoms last? When should you test? A Covid timeline.

The highly contagious subvariant of Omicron, known as BA.2, has prompted concern among health officials as it becomes the dominant version of the coronavirus around the world. So far, signs suggest that BA.2 is 30 to 80 percent more transmissible than the original version of Omicron, and cases are already going up in several states across the United States.

While we have tools to prepare for a spike in cases — vaccination, frequent testing, high-quality masks and social distancing — experts worry that the public’s capacity to keep up with precautionary measures is waning.

To make matters even trickier, you won’t know for sure if you’re dealing with BA.2 or the original Omicron subvariant. “It’s not something that’s reported clinically,” said Dr. Stuart Ray, an infectious diseases specialist at Johns Hopkins University School of Medicine in Baltimore.

But regardless of which subvariant you have, you can apply the same course of action, Dr. Ray said. You should mark your calendar and test at the first sign of illness, track your oxygen levels with a pulse oximeter and be on the lookout for signs that your infection is becoming more serious, like difficulty breathing or chest pains.