Governors in Texas and Mississippi announced Tuesday that the states would be lifting mask mandates and allowing businesses to operate at full capacity, citing declining Covid cases and increasing availability of vaccines as reasons for reopening.

According to Texas Gov. Greg Abbott, the "state mandates are no longer needed."

While experts are worried for Texas and Mississippi because they see the rollbacks as premature, those states' decisions could also compromise the rest of the country's fight against Covid.

"At this level of cases with variants spreading, we stand to completely lose the hard-earned ground we have gained," Dr. Rochelle Walensky, head of the Centers for Disease Control, said of the rollbacks on Monday during a White House briefing.

Although there are now three approved vaccines for Covid, "what's really helping to keep safe and protected this point is our viral control practices," such as masking and social distancing, Dr. James McDeavitt, senior vice president and dean of clinical affairs at Baylor College of Medicine in Waco, Texas, tells CNBC Make It.

Here's how the change of rules in Texas and Mississippi — and any other states that follow suit — could affect you and your health.

It makes room for variants to emerge and spread across the country

New, more contagious variants of the coronavirus are already being monitored in the U.S. Removing restrictions and safety measures like masks sets the stage for more spread, which gives the virus opportunities to mutate. Those variants can potentially make vaccines less effective.

"We need to use every tool we have to control this pandemic," Dr. Barbara D. Alexander, president of the Infectious Diseases Society of America, said in a statement Wednesday.

This is another reason why public health officials are urging people to get vaccinated as soon as possible. (To check your eligibility status, you can use NBC News' plan your vaccine tool.) "We are in a vaccine versus variant race," McDeavitt says. "The faster we get people vaccinated, the less the chance that we have a variant emerge that is resistant to the vaccine."

There could be another surge

McDeavitt worries that people will interpret the governor's actions as permission to stop wearing masks and let their guard down.

"We still need to wear masks and social distance," he says. Many people will continue to wear masks to "set an example for the community," he adds. Some businesses have already signaled that they're still going to require customers and employees to wear masks.

Jeffrey Zients, the White House's coronavirus response coordinator, urged other state and local leadership to keep wearing masks and "keep the course," he said Wednesday. "We hope other elected officials who have the authority in their domains will, in fact, listen," he said.

If people relax prevention measures, it could result in another surge of Covid cases, McDeavitt says, which could go beyond Texas or Mississippi.

"We will come out of the back end of the surge, but it'll prolong the period of time before we reach herd immunity and, in a way, increase the chances that a variant could emerge that is going to be more problematic," McDeavitt says.

The CDC still recommends that people wear face masks to prevent spreading or contracting Covid. Masks block respiratory droplets from an infected person, and provide a degree of protection to the wearer. Last month, the CDC released new data that wearing a well-fitting surgical mask under a cotton mask, aka "double masking," reduces potential exposure to Covid-containing respiratory droplets and aerosols by up to 96%.

Herd immunity for the country will be delayed

Currently, the U.S. is "nowhere near herd immunity," the point at which enough people are immune to an infectious disease (through vaccination and past infection) that it is very difficult for it to spread, Adam MacNeil, an epidemiologist at the Centers for Disease Control and Prevention, said Friday.

The U.S. is recording at least 65,400 new Covid-19 cases each day, based on Johns Hopkins University data.

Texas has administered 5.08 million doses of vaccine as of March 2, according to Our World in Data. (The population of Texas is 29 million people, according to U.S. Census Bureau data.)

Removing crucial mitigation efforts like wearing masks and maintaining social distance at this stage in the pandemic doesn't just affect Texas and Missisippi. It also will delay the country's progress toward herd immunity even longer.

"The clock is ticking on that," McDeavitt says.

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