WASHINGTON, United States (AFP) — Half of the US population is now fully vaccinated against COVID-19, the White House said Friday, as inoculations rise in response to the surging Delta variant of the novel coronavirus.

“50 per cent of Americans (all ages) are now fully vaccinated. Keep going!” Cyrus Shahpar, White House COVID-19 data director, said in a tweet.

That means more than 165 million people have received either the two-dose Moderna or Pfizer vaccine or the one-and-done Johnson & Johnson shot. 

The threshold of half of all adult Americans fully vaccinated was reached in late May.

Shahpar said the seven-day average of newly vaccinated people is up 11 per cent from last week and up 44 per cent over the past two weeks.

For four straight weeks, the average number of people getting vaccinated each day has risen, White House COVID coordinator Jeff Zients said Thursday.

The United States is the nation hardest hit by the pandemic with 615,000 deaths.

Biden has been pressing hard for Americans to get vaccinated ever since he took office in January. 

The aggressive vaccination program had raised hopes of a return to some semblance of normal life this summer, but the plan did not pan out because of the Delta variant.

After peaking in April, the rate of new inoculations fell off sharply.

Daily new cases, deaths and hospitalizations are up sharply in recent weeks, and cities like New York and Los Angeles are imposing new restrictions such as demanding proof of vaccination for entering indoor venues like restaurants and gyms.

Last week there was an average of 90,000 new coronavirus cases per day. Florida and Texas accounted for a third of them, the White House said.

That figure marks a 43 per cent rise from the previous week, the Centers for Disease Control and Prevention said Thursday.

The level of community transmission of the virus is “high” or “substantial” in 85 per cent of the country, the CDC says.

Hospitalisations are up to a nationwide daily average of around 7,300 per day in the seven days. Deaths are up sharply at around 380 per day.

Breakout cases of infection among vaccinated people are still rare but preliminary research shows that when they do happen, the risk of contagion is greater than with previous strains of the virus. 

And this poses a higher risk for the non-vaccinated who come into contact with infected vaccinated people.

In light of all these numbers the CDC changed course recently and recommended the wearing of masks indoors in high risk areas, even for people who are vaccinated.