The authors of the study estimate that a vaccine that’s 95 percent effective would still leave nearly 10 million to contract COVID-19 and 160,000-plus to die from the disease in the six months after the vaccine’s introduction. That’s because the sheer number of infected people is increasingly so rapidly.

Over 202,200 new COVID-19 cases and 1,500 deaths were reported in the U.S. on Monday, according to data from The New York Times. There has been an average of 201,756 new cases per day over the past week, a 16 percent increase compared to the previous two weeks.

Also, “the benefits of a vaccine will decline substantially in the event of manufacturing or deployment delays, significant vaccine hesitancy, or greater epidemic severity,” states the paper, entitled “Clinical Outcomes of a COVID-19 Vaccine: Implementation Over Efficacy.”

One of its authors, Rochelle Walensky, has been picked by President-elect Joe Biden to run the Centers of Disease Control and Prevention and currently serves as the Chief of Infectious Diseases at Massachusetts General Hospital.

The paper’s authors didn’t respond to Newsweek’s request for comment in time for publication.

The U.S. expects nearly 6.4 million doses of Pfizer’s COVID-19 vaccine, estimated to be 95% effective, before the end of the year, according to officials at the Trump administration’s Operation Warp Speed. The pharmaceutical company awaits emergency approval from the Food and Drug Administration (FDA).

Last week Moderna applied for FDA emergency use authorization for its COVID vaccine, estimated to be 94.5% effective.

FDA approval of both vaccines is expected in the coming weeks. The agency confirmed the safety and efficacy of Pfizer’s vaccine in two analyses released Tuesday. It said the vaccine “met the prescribed success criteria” in a clinical study.

Moncef Slaoui, chief scientific adviser to Operation Warp Speed, has warned that although a COVID-19 vaccine brings a glimmer of hope in the country’s fight against the virus, Americans must remain cautious.

“We have a vaccine, there is light at the end of the tunnel, but we will not all have the vaccine in our arms before May or June, so we need to be very cautious and vigilant,” he told CNN anchor Jake Tapper on State of the Union Sunday.

“This pandemic is ravaging the country. We need to take our precautions, wear our masks, wash our hands, keep our distance, remain aware that this virus is a killer,” Slaoui continued.

“Bluntly stated, we’ll get out of this pandemic faster if we give the vaccine less work to do,” A. David Paltiel, one of the paper’s authors and a professor at the Yale School of Public Health, told The New York Times.

Since the pandemic began the U.S. has reported over 14.9 million confirmed coronavirus cases and 283,800 deaths, according to Johns Hopkins University.