Coronavirus cases dropped to their lowest level since mid-July in the greater Washington region last week, but keep your mask on.

Infections will probably rebound this fall and winter, and could force authorities to reverse course and tighten restrictions on public activities, officials and health experts said.

Six months after the virus erupted in our area, its persistence has frustrated early hopes that shutdowns and other measures would have mostly contained it by now. The region has fared better than much of the country in battling the disease. But it has failed to drive down infections as much as the Northeast and many foreign countries.

“The reality is it’s going to get worse,” said Boris Lushniak, dean of the University of Maryland School of Public Health and an acting U.S. surgeon general during the Obama administration. “The real question is how bad is it going to get.”

Fairfax County Health Director Gloria Addo-Ayensu said: “Pandemics can take a long time. Typically some pandemics that we know about have taken 18 months, and sometimes more. We still have a lot of days ahead of us.”

Cases are expected to rise partly because colder weather means people will spend more time indoors, where the virus spreads more easily. Upticks are already occurring in some states and Europe.

“Covid fatigue,” or public weariness with following health guidelines, also is a factor. Local health departments have increased their capacity to conduct coronavirus tests and carry out contact tracing, two critical tools in fighting the pandemic. But the benefit is limited if people don’t get tested, resist cooperating with contact tracers or engage in risky behavior.

“We consistently are seeing large family gatherings, large social gatherings, and different activities like that being associated with cases that have tested positive,” Montgomery Health Officer Travis A. Gayles said. “We are trying to retool our messaging . . . to remind people why it’s important to adhere to the rules.”

Gayles is concerned by a drop since late July and August in the number of Maryland residents getting tested for the novel coronavirus.

“Testing is down, in spite of there being capacity to support those coming in,” Gayles said.

The D.C. area is having a mixed experience with contact tracing. That’s the process in which people who test positive are asked to isolate for 10 days and identify others with whom they have come in close contact. The latter are then called and asked to quarantine for 14 days.

Most people are receptive and cooperative, contact tracers said, but logistical challenges and some public reluctance hamper the effort.

“Sometimes we’re not able to reach people, because people are hesitant to answer [calls from] numbers that they’re not familiar with,” D.C. contact tracer Brooke Moore said.

“You get people who are very helpful and tell you everything. . . . [But] there are some angry people who don’t think we have their best interests at heart,” said Lisa Frost, a contact tracer in Montgomery. “There are people who don’t even take the virus seriously.”

The District reported that it was failing to meet its current target for completing interviews within three days with people who test positive. Also, the share of people who provided information about their close contacts was only 36 percent.

“We can have the best systems, but we need participation,” D.C. Mayor Muriel E. Bowser (D) said. “Six months into this, we’re all kind of sick of covid . . . but we know that we have to continue to be vigilant.”

The District and Montgomery and Prince George’s counties have held off moving to Phase 3 of reopening. That’s a disappointment for many who expected the region to be further along. (Virginia is in Phase 3.)

“A few months ago, I would have believed [the District] would be able to move into Phase 3 by now,” said Lynn R. Goldman, dean of George Washington University's School of Public Health. Instead, she said, “We are seeing an uptick in the U.S., and we ignore it at our peril.”

It could be worse. Our region had neither the severe surge that New York City experienced in the spring, nor the second wave seen in the summer in Florida and Texas.

Eric Toner, senior scholar at the Johns Hopkins Center for Health Security, divided states into three groups to describe their different experiences with the coronavirus.

One group — including New York, New Jersey and California — was struck early, with no time to prepare, and saw “a huge spike in cases, which really stressed their health systems,” Toner said.

A second, primarily in the South and Southwest, had large surges in the summer because they “did not implement consistent public health intervention policies,” he said.

The D.C. region is in the third group, states that “never had a big spike . . . and have been pretty successful in containing cases at a moderate, manageable level,” Toner said.

Still, the D.C. region has not succeeded in driving down the infection rate as low as New York and much of New England have done since spring. The District has more than double the number of daily average cases per capita as New York.

“The whole Northeast, New England, their rates are [now] incredibly low, much better than ours,” GWU’s Goldman said.

Our overall rate of cases and deaths during the pandemic also is dramatically higher than that of foreign countries such as South Korea and Germany, a difference that experts attribute largely to failures at the federal level.

“Almost every other nation had a national plan and a national response,” U-Md.’ s Lushniak said. “The success of many of our European friends was owing to measures adopted more aggressively and immediately by the highest levels of the government.”

Lushniak didn’t name the Trump administration, but it was clear whom he faulted.

“Even to this day, we are getting mixed messages on something as important as mask-wearing,” he said. “We are still getting mixed messages on something as important as large group gatherings. We are still getting mixed messages on testing.”