WASHINGTON (AFP) - One hundred million people in the United States are now fully vaccinated against Covid-19, White House pandemic response coordinator Jeff Zients said on Friday (April 30).

"That's 100 million Americans with a sense of relief and peace of mind knowing that after a long and hard year they're protected from the virus, knowing their decision to get vaccinated protects not just themselves, but also protects their families, their friends and their communities," he said.

The country has distributed 237 million doses, and 55 per cent of adults have now received at least one dose.

The US vaccination campaign got off to a shaky start in December, but the rate of immunisation rose rapidly through spring.

The vaccination rate peaked in early April and is now slowing, since many people who wanted to receive vaccines have already received them.

Health groups are now attempting to help people who faced access barriers, or who still have questions about whether they should be vaccinated.

According to data from the Kaiser Family Foundation, Republicans remain more likely to say "definitely not" to a vaccine, with 29 percent saying they will never be immunised, against 5 per cent of Democrats and 9 per cent of independents.