The United States Food and Drug Administration announced on Friday that has narrowed the use of the Johnson & Johnson Covid-19 vaccine to use by adults unwilling or unable to receive the Pfizer-BioNTech or Moderna mRNA jabs.

The use limitation relies on the reported risk of developing thrombosis with thrombocytopenia syndrome (TTS), a potentially fatal mix of blood clots and low platelet counts related to receiving the J&J vaccine.

"We recognize that (J&J's) Janssen COVID-19 Vaccine still has a role in the current pandemic response in the United States and across the global community (...) The agency will continue to monitor the safety of the Janssen COVID-19 Vaccine and all other vaccines," FDA's biologics evaluation center director Peter Marks said in an official statement.