Quote: "We know this has been a trying year."

That's not just us talking.

It's part of a statement by the CEO of Wal Mart, and the reason behind it is part of our first story today.

The statement goes on to say: "We hope our associates will enjoy a special Thanksgiving Day at home with their loved ones."

It's the first time in more than 30 years that Wal Mart has closed on Thanksgiving.

Best Buy, Dick's Sporting Goods, and Macy's are some of the other companies doing this.

The reason they've been open in the past on "turkey day" was to get a head start on Black Friday, the day after Thanksgiving.

That's traditionally been the start of the holiday shopping season.

Critics have said their employees should be allowed to stay home with their families, and that challenges brought on by the coronavirus pandemic have factored into these companies' decision to close this Thanksgiving.

However, they don't wanna be forced to close on black Friday.

U.S. cities and states enacted shutdowns earlier this year to try to slow the spread of coronavirus, but some businesses like Target, Costco and Amazon were allowed to stay open because they sell groceries, which are considered essential.

While clothing stores and retailers like Macy's, which don't sell groceries, were forced to close.

That caused Macy's to lose sales to its competitors.

So it's working with state and local leaders to show it has safety measures in place and to discourage officials from forcing stores to close again at a time when shopping is so important to them.

So when will everything just ... get back to normal?

That is the question no one seems to know the answer to.

And even though several drug companies, including AstraZeneca now, have announced progress and making a coronavirus vaccine, that's only one step in a big challenge.

With dozens of human trials underway, scientists around the world are racing to develop a COVID-19 vaccine.

Even after the vaccine comes ...

When can you get the vaccine?

(Portuguese) The hope for COVID-19 vaccines...

But experts warn a vaccine won't be a magic bullet.

And there are several challenging steps ahead before a safe and effective vaccine can have an impact on the spread of the virus.

First, any vaccine must be approved or authorized by a regulatory body.

If it's going to be used in the United States, for example, it needs to get a green light from the US Food and Drug Administration.

Under usual circumstances before the pandemic, it would take a very long time to get approval from the FDA for a vaccine.

But now, because of the pandemic, vaccines are undergoing what's called "emergency use authorization."

That could take just a matter of weeks.

Usually, once a vaccine gets the green light from regulators, the manufacturing process goes full steam ahead.

But companies like Pfizer didn't wait.

Instead, they have produced their vaccine candidates in large quantities.

Among the earliest vaccines out of the gate are the so called "mRNA" vaccines.

Companies including Pfizer and Moderna are working on this type.

These are new vaccines--there are no vaccines out there currently that are made this way.

While many vaccines inject a weakened or inactive pathogen into the body, mRNA vaccines on the other hand deliver a small piece of the pathogen's genetic code into a human cell.

This prompts the body to produce a synthetic copy of the virus's attacking properties, and eventually the body launches a counterattack against the quote "invader."

One big advantage of mRNA vaccines is that they can be made quite quickly.

Many other types of vaccines are harder to manufacture and need more time.

Still, we need billions of doses for the world's population.

Once vaccines are made, a new challenge arises: how to get them to billions of people around the world.

Experts say that handling vaccines is a delicate matter.

Vaccines are stored in refrigerators or sometimes in freezers, however, this Pfizer vaccine is different.

It needs to be stored at a very cold temperature--minus 75 degrees Celsius.

That's minus 103 Fahrenheit.

Doctors' offices, pharmacies ...

They don't have freezers that go that low, so distributing and storing these vaccines is tricky.

Once the vaccine is distributed, it likely won't be mandatory in the U.S. and many other countries.

People have to choose to take it.

If you have a great vaccine and people aren't willing to take it, it's not going to work.

Many people are suspicious of the COVID-19 vaccine.

Polls have shown that many Americans don't want to get it.

It will take many months to vaccinate the population and in the meantime, measures such as wearing masks and social distancing will be crucial.

Nobody knows exactly when this vaccine will be ready for people to use, but the folks who are running the vaccine programs for the United States government, they say it's very possible that we could have shots in arms before the end of the year.

We would start with high-priority groups that would include the elderly doctors and nurses and others who are taking care of COVID patients.

People with underlying conditions, they would go first.

So if you're not in one of these high-priority groups, it is possible that you would have to wait until the spring to get a COVID-19 vaccine.

Some health officials also promote contact tracing as a way to slow the spread of coronavirus.

It keeps track of where people go and wherever they might have come in contact with the disease.

Privacy advocates have deep concerns about this because people's personal information would be tracked by an outside company or government.

There are also concerns about whether this information would be used to limit people's freedoms whenever they were exposed to coronavirus.

The communist government of China doesn't allow the degree of freedom that Western democracies do, and it's using in promoting QR codes or electronic barcodes as a means of tracking people's travel and health history.

China's reopening is happening under the watchful eye of big data and perhaps Big Brother, local governments tracking the movements of hundreds of millions.

We noticed that start of this effort back in mid February, arriving in Shanghai from Beijing, each arriving passenger required to write down health and travel history and register for your personal QR or barcode.

Have you been traveling away from China for the 30 days? No ...

A few weeks later, and Shanghai had rolled out its QR codes citywide.

Walking into a restaurant, hotel, shopping mall, you're expected to show it.

Here in Shanghai, shop owners and hotel managers have told us a green means you're clear to go in, yellow or red suggests you've been in an area with high exposure to the virus and it could mean quarantine.

It is all part of "contact tracing," an effort to track and contain confirmed cases here in China.

Here in China, it's done on the widely used WeChat and Alipay apps.

To stop the spread of the virus, contact tracing is an essential step, and this is why similar initiatives are being adopted in many places around the world.

Major Chinese tech companies are finding other innovations amid the outbreak.

CNN spoke with Shin Chung hwa from Alibaba.

He does artificial intelligence research, he says.

He says more than 160 hospitals in China and others in Japan are using the CT image analytics to help diagnose coronavirus.

The whole approach is nearly 60-times faster than human detection.

Alibaba (is) also turning to genome sequencing, analyzing the viruses DNA to help diagnose the virus.

They say they can screen 20 samples simultaneously.

The tech giant (is) also involved in tracking future hotspots of the virus.

It's all giving the company potential access to so much personal health data, raising privacy concerns.

So we don't store any data.

We just analyze it and then passed the result to (the) hospital, where (a) doctor can use it as a reference to exercise their own medical judgement.

What about the government, though?

Particularly with the QR codes.

Personal local data and health information, it might prove effective in containing the spread, but is it the start of China using a pandemic to closely track its citizens and those potentially of other countries?

Should they export this technology?

Local governments using the QR (codes) have publicly posted they will discontinue them as soon as the outbreak ends.

Who's going to determine, like, for example, when the pandemic actually ends?

When is the end point?

When should governments or companies actually delete the personal data or the tracing data that they're actually collecting?

For now, many here in China focused on stopping the spread and navigating their new normal.

David Kaufer, CNN, Shanghai.

St. Augustine, Florida is the oldest city in the U.S.

So it may not seem surprising that erosion from a recent tropical storm would reveal a historic shipwreck.

Researchers think this is the remains of a merchant ship that unknowingly sailed into a hurricane in the 1800s and wound up on the shore here.

Its crew survived, and apparently so did the wreckage, protected by the sand from the sun and the salty air.

Hard to say how many gallons of water washed over it, but it is a "sloop-er" discovery that no one "driftwood" forget now that it's made its bark like a true merchant man!

You knew we were not going to set sail without wrecking your Tuesday with some puns.

Bosse High School is in Evansville, Indiana, and the reason I mentioned that is because Bosse subscribed and left a comment on our YouTube channel.

Do the same thing and you could hear your school next Monday when we return from the Thanksgiving break.

We are thankful for you, the best audience in news.

I'm Carl Azuz for CNN.