NEW YORK (AP) — States are beginning to ease coronavirus restrictions, but health experts say we don’t know enough yet about variants to roll back measures that could help slow their spread.

As more people are vaccinated and the daily number of COVID-19 cases and deaths decline, public health officials have relaxed mask mandates and re-opened businesses like restaurants, bars and retail establishments.

But the country’s genetic surveillance system is still not robust enough to accurately track variants, which means they could be spreading unchecked.

Experts say continued public health measures like social distancing can help avoid a variant-powered surge of the virus.