With Labor Day come and gone, U.S. health experts have tallied the nation's number of COVID cases and, according to data from Johns Hopkins University, more than 4 million virus cases have been reported in the last four weeks alone.

According to CNN, COVID cases have generally been on the rise since early summer and the country's seven-day average of new cases Monday (137,270 daily) was more than four times higher than Labor Day of last year (39,355 daily), according to Johns Hopkins data.

Last week, the US Centers for Disease Control and Prevention Director Dr. Rochelle Walensky urged unvaccinated Americans not to travel for the holiday and reminded vaccinated people that the high rate of virus transmission meant it could be risky for them to travel as well.

Leading health experts agree that getting vaccinated can be a safeguard. 

CNN quoted Dr. Megan Ranney, professor of emergency medicine and associate dean at Brown University's school of public health as saying, "Everyone that I'm hospitalizing is not vaccinated. We are, by and large across the country, not needing to hospitalize people that have gotten both doses of the vaccine. This is a disease of the unvaccinated right now."

Alabama, Wyoming, Idaho, Mississippi and West Virginia all have less than 40% of their populations vaccinated, according to the CDC.