New York, Feb 28 (IANS): The US Food and Drug Administration (FDA) has approved the single-shot Johnson and Johnson (J&J) Covid-19 vaccine for emergency use, the third to be authorised against the disease in the country.

The authorisation allows the vaccine to be distributed in the US for use in individuals 18 years of age and older, the FDA said on Saturday.

"The authorisation of this vaccine expands the availability of vaccines, the best medical prevention method for Covid-19, to help us in the fight against this pandemic, which has claimed over half a million lives in the United States," Acting FDA Commissioner Janet Woodcock, sia din a statement.

The totality of the available data provides clear evidence that the Janssen Covid-19 Vaccine may be effective in preventing the coronavirus, the FDA said.

The Janssen Covid-19 vaccine is manufactured using a specific type of virus called adenovirus type 26 (Ad26).

The vaccine uses Ad26 to deliver a piece of the DNA, or genetic material, that is used to make the distinctive "spike" protein of the SARS-CoV-2 virus.

While adenoviruses are a group of viruses that are relatively common, Ad26, which can cause cold symptoms and pink eye, has been modified for the vaccine so that it cannot replicate in the human body to cause illness.

After a person receives this vaccine, the body can temporarily make the spike protein, which does not cause disease, but triggers the immune system to learn to react defensively, producing an immune response against SARS-CoV-2.

The Janssen Covid-19 Vaccine is administered as a single dose.

At this time, data are not available to determine how long the vaccine will provide protection, nor is there evidence that the vaccine prevents transmission of SARS-CoV-2 from person to person, the FDA said.