As many people around the holidays shifted to using rapid coronavirus tests, infectious disease experts say they’re confident the at-home swabs are picking up the new omicron variant.

All of the data shows that the rapid tests are detecting the extremely contagious omicron variant, just as well as the tests picked up the highly contagious delta variant, according to Harvard epidemiologist Michael Mina.

Many have been concerned about the rapid antigen COVID-19 test’s reliability, as some people have been staying negative in the first days they have symptoms. But Mina said this means the vaccines are working.

“This is expected,” he tweeted about people testing negative while it feels like they’re infected. “Symptoms don’t = contagious virus … This is literally a reflection of the fact that vaccines are doing their job!”

Mina explained that with vaccines, immunity kicks in quickly after getting exposed to COVID-19. That causes the symptoms to start before the virus grows up and becomes infectious.

The rapid antigen tests turn positive when people are contagious, he said.

“If you are symptomatic and negative — although it means you’re (probably) not contagious at that moment, be very very cautious,” Mina tweeted. “Quarantine even if possible and test the next morning or that night. (Sometimes even longer)

“With Omicron, the virus is growing even faster than before so please DO take precautions if you have symptoms,” he added. “Listen to your symptoms for a reasonable amount of time and retest even daily if possible.”

Abbott produces the popular at-home BinaxNOW rapid antigen tests. The company said it conducted an assessment of the omicron variant and is “confident our rapid and PCR tests can detect the virus.”

“While the Omicron variant contains mutations to the spike protein, Abbott’s rapid and molecular tests — antigen and PCR — do not rely on the spike gene to detect the virus,” Abbott said in a statement.

Abbott is manufacturing more than 100 million COVID-19 rapid and PCR tests a month, as testing demand balloons across the U.S. and world.