WASHINGTON, Sept. 9 (Xinhua) -- More students are returning to campuses across the United States as new school year begins, adding risks for new COVID-19 infections and the country's control over the pandemic.

Sept. 8 marks the first day of school for more than 1.8 million American students, said a CNN report. Several schools have already had to temporarily shut down again after COVID-19 outbreaks this school year. Others, including some universities, have managed to keep their cases low after testing every student returning to school.

Several universities have already detected increasing new COVID-19 cases.

"The back-to-school season has brought new challenges to the control of the pandemic," Zhang Zuofeng, a professor of epidemiology and associate dean for research with the school of public health at University of California, Los Angeles, told Xinhua.

A survey of The New York Times on more than 1,500 American colleges and universities has revealed in early September at least 51,000 cases and at least 60 deaths since the pandemic began.

States including Texas, Alabama and North Carolina have reported over 4,000 cases among universities.

In a New York Times review of 203 counties in the country where students comprise at least 10 percent of the population, about half experienced their worst weeks of the pandemic since Aug. 1. In about half of those, figures showed the number of new infections is peaking right now.

Data shows that despite the surge in cases, there has been no uptick in deaths in college communities, which suggests lower COVID-19 death rate among young people than elder ones. However, many people are concerned that young people who are infected will contribute to a spread of the virus throughout the community.

John Jenkins, president of the University of Notre Dame, which shifted to online classes after reporting a rise in infections, said their contact tracing analysis indicates that most infections are coming from off-campus gatherings.

"Students infected at those gatherings passed it on to others who in turn passed the virus on to a further group, resulting in the positive cases we have seen," Jenkins said.

In order to slow the spread of the virus, schools have taken stricter control efforts, including ordering face masks and physical distancing, distributing hand sanitizer and thermometers, and moving large lecture courses online.

Some students have faced serious consequences for breaking the rules. Northeastern University in Massachusetts dismissed 11 students last week for violating safety precautions. New York University, Ohio State, Purdue and West Virginia University have all suspended students over violations of rules intended to curb the virus spread on campus, according to The New York Times report.

Over the summer, a group of faculty members and students from the California Institute of Technology and elsewhere analyzed reopening plans from about 500 colleges and universities.

They reported that 27 percent of schools were planning to test undergraduates as they enter campus; about 20 percent planned to test their communities regularly to some extent; the vast majority did not.

"Large gatherings of students on campus, in classrooms and restaurants, may make schools a hotbed for outbreaks. If strong protective measures are not in place, there will be high risks of local outbreaks," Zhang told Xinhua.