Pfizer and BioNTech on Monday submitted preliminary clinical data to US health authorities as part of their effort to seek authorization for a third dose of their Covid-19 vaccine for all Americans.

Last week, the United States approved the booster shot of Pfizer-BioNTech and Moderna vaccines for people with weakened immune systems.

Pfizer and BioNTech presented the results of their Phase One trial that evaluated the safety and efficacy of a third shot.

"The data we've seen to date suggest a third dose of our vaccine elicits antibody levels that significantly exceed those seen after the two-dose primary schedule," Albert Bourla, Pfizer's Chairman and Chief Executive Officer, said in a statement.

"A booster vaccine could help reduce infection and disease rates in people who have previously been vaccinated and better control the spread of virus variants during the coming season," said BioNTech Co-founder Ugur Sahin.

The companies plan to submit the same information to European authorities in the coming weeks. 

The move comes despite appeals by the World Health Organization for a moratorium on booster shots to help ease the drastic inequity in dose distribution between rich and poor nations. Israel has also began administering third doses to its citizens.

An advisory committee of the Centers for Disease Control and Preventions, a top US healthcare agency, is slated to meet in late August to discuss the approval of a third dose of the vaccine for adults over 65, care home residents and healthcare workers.