NEW YORK - About 60 percent of the US population is heading into the winter months with reduced protection against the coronavirus, according to data released this week by the US Centers for Disease Control and Prevention (CDC), while health experts warned that those who were vaccinated early in the year are likely to have waning immunity.

Currently, around 6 in 10 Americans are fully vaccinated with over half having received their last shot more than six months ago, the threshold recommended for a Moderna or Pfizer booster. However, combined with the 100 million unvaccinated people, only 40 percent of the Americans are at their strongest immunity level against COVID-19, said the CDC.

As of Saturday morning, 229,291,004 people received at least one dose of COVID-19 vaccine, making up 69.1 percent of the whole US population. Fully vaccinated people stood at 195,920,566, accounting for 59 percent of the total. A total of 33,454,832 people, or 17.1 percent of the fully vaccinated group, received booster shots, according to CDC data.

Meanwhile, The New York Times (NYT) reported that the seven-day average of confirmed cases of the pandemic stood at 93,196 nationwide on Friday, with the 14-day change striking a 30 percent rise. COVID-19-related deaths were 1,134 on Friday, with the 14-day change realizing a 6 percent fall.

More shockingly, according to two new studies published by the CDC on Friday, pregnant women who become infected with the Delta variant are at increased risk of a stillbirth or dying during childbirth. The research expanded on reports from doctors nationwide who have noted an unprecedented rise in pregnant women becoming critically ill with COVID-19, particularly as the highly contagious variant has taken hold.

"We are seeing loads of pregnancy complications from COVID-19 infection," Ellie Ragsdale, director of fetal intervention at UH Cleveland Medical Center, was quoted as saying. Those complications include premature deliveries, abnormally high blood pressure in pregnant women, as well as pregnancy loss, said Ragsdale.

One of the new studies analyzed the outcomes of more than 1.2 million pregnancies nationwide between March 2020 and September of this year. Stillbirths were rare in the United States before the pandemic, at a rate of 0.59 percent. Those rates remained similar even when the pandemic hit, at 0.64 percent among women who were never diagnosed with COVID-19.

But the rate of stillbirths rose to 0.98 percent among expectant mothers infected with the coronavirus, according to the CDC report. And once the Delta variant took hold in July this year, the rates rose exponentially: 2.7 percent of COVID-19-positive pregnancies ended in stillbirth.