County Halts Use Of J&J Vaccine After Rare Blood-Clot Cases

BETHESDA, MD — Montgomery County will temporarily halt using the Johnson & Johnson coronavirus vaccine after six recipients in the U.S. suffered blood clots, officials announced Tuesday.

The county's mass vaccination site — located at Montgomery College's Germantown campus — planned on administering about 960 doses of the single-shot vaccine on Tuesday. They will be substituted with the first dose of the Pfizer vaccine.

"This morning's news regarding the Johnson & Johnson vaccine is causing concern for many and it is understandable," said County Executive Marc Elrich. "I am one of millions who received the Johnson & Johnson vaccine and I have felt no side effects. Until further notice our health department will be substituting Pfizer doses for the Johnson & Johnson doses."

The county's top health official, Dr. Travis Gayles, said none of the blood-clot cases came from Montgomery County.

All six recipients were women between the ages of 18 and 48, and symptoms occurred six to 13 days after vaccination, the U.S. Centers for Disease Control and Prevention said in a joint statement with the Food and Drug Administration.

As of Monday, nearly seven million people have received the Johnson & Johnson vaccine. While those blood clot cases "appear to be extremely rare," the CDC and FDA say they are taking "all reports of health problems following COVID-19 vaccination very seriously."

The CDC said it will hold a meeting on Wednesday to review these cases and assess their potential significance.

How the Johnson & Johnson Vaccine Works

There are three vaccines currently available in the United States: Pfizer; Moderna; and Johnson & Johnson.

Both Pfizer and Moderna deliver mRNA — a genetic recipe that teaches your body how to build the spike protein found on the surface of the coronavirus. If the real virus enters the body, your immune system will recognize it and know how to fight it.

Johnson & Johnson, however, uses a different technology to prime the body to fight against COVID-19. Instead of mRNA, it utilizes an adenovirus — a common cold virus that cannot replicate and make a person sick once it enters the cells.

Ultimately, the cold virus will deliver the coronavirus-fighting genetic blueprint into the cells and teach the immune system how to recognize the spike protein found on the surface of the coronavirus.

Adenovirus vaccines can be refrigerated for up to three months at 36 to 46 degrees Fahrenheit, according to Johns Hopkins University.

Clinical trials showed the Johnson & Johnson vaccine as being less effective against the virus compared with the vaccines developed by Moderna and Pfizer. The company said the vaccine has a 72 percent efficacy rate among trial participants in the U.S., but is about 85 percent effective against the most severe forms of the virus. Moderna and Pfizer tout efficacy rates at or near 95 percent.

Johnson & Johnson's vaccine is for people 18 years old and up.