Drug stores and grocery stores have played a vital role in delivering Covid-19 vaccines to Americans across the country. Now they are trying to find a way forward after the Food and Drug Administration asked states Tuesday morning to temporarily suspend distribution.

CVS Health announced it has stopped all Johnson & Johnson Covid-19 vaccines in its stores. Company spokesman Mike DeAngelis said affected customers would receive an email informing them that their scheduled appointments were being canceled. He said it will follow these customers to reschedule as it continues to offer shots developed by other manufacturers.

Walgreens said in a statement that J&J vaccines would also be exposed in its stores and outside clinics. It said it would reach out to people with appointments and postpone them with another shot if supplies allowed.

Wegmans said in a statement on his website that he canceled all appointments for J&J vaccines.

Retailers began sharing their responses on Tuesday at the request of the FDA. The federal agency said it took the step “out of caution” after six women in the US developed a rare bleeding disorder. Nearly 7 million Americans have received the vaccine, according to the Centers for Disease Control and Prevention.

J & J’s vaccine is not as widely used as that of Pfizer-BioNTech or Moderna. However, the recordings offer unique advantages. They can be stored at refrigerator temperature for months and only take one shot – unlike Pfizer and Moderna, which require freezers and two rounds of shots about a month apart. This has made J & J’s vaccine an attractive option, especially for hard-to-reach populations like Americans who live in poorer communities, rural areas, or tribal areas.

It’s unclear how much of the drugstore and grocery store vaccine supply comes from J&J compared to other manufacturers – and what part of their vaccine appointments could disrupt the FDA request.

CVS offers Covid vaccines in approximately 2,000 stores in 49 states. DeAngelis, the company’s spokesman, declined to say how many of these stores use the J&J vaccine and how many of them deliver vaccines developed by Pfizer-BioNTech or Moderna.

Some states, including New York, have announced plans to use Pfizer’s two-shot vaccine at J&J for appointments that have already been made.