No one wants summer to end, especially young people enjoying the freedom of long, hot days with no school schedules or homework to limit their fun.

And especially after the last school year.

But the telltale sign of store shelves filling up with "back to school" items means it's coming sooner than anyone wants to admit.

This year, everyone aged 12 and over has one more item to consider adding to their list as they prepare for the return to middle school, high school or college: A vaccine against COVID-19.

"This year, getting ready for school means more than just pencils and notebooks. Vaccinating students helps us all get back to our normal lives and keeps everyone safer. That's why we hope everyone will get the facts and include vaccination in their back-to-school plans," said Tammy Chang, M.D., M.P.H., M.S., an adolescent health physician and health care researcher at the University of Michigan's academic medical center, Michigan Medicine. "Now's the time to start, because it takes time for the vaccine to teach your immune system to recognize and fight the coronavirus."

July and early August are especially critical times for people age 12 to 17 to get vaccinated, because people in that age range have just one vaccine available to them: the two-dose Pfizer/BioNTech variety. It takes five weeks to build up full protection.

"August 2 is a key date, and it's coming faster than you think," said Chang. "If you get your first dose of a two-dose vaccine before that day, and your second dose three weeks later, you'll be considered fully vaccinated two weeks after that. That means you'll be fully protected for Labor Day and the start of many classes."

SEE ALSO: COVID Vaccines and Kids: 20 Things to Know

Meanwhile, students over age 18, and faculty and staff members, who will enter classrooms this August or September, have three vaccines to choose from: Pfizer's, the two-dose vaccine from Moderna, and the one-dose Johnson & Johnson/Janssen vaccine.

"If you're over 18 and choose the one-dose vaccine, get vaccinated by August 23 to be considered fully vaccinated by Labor Day," Chang said. "For a two-dose vaccine, start now to be fully vaccinated by the start of classes. And if you got your first dose of Pfizer or Moderna more than a few weeks ago, but didn't get your second yet, it's definitely not too late. Go get it as soon as you can, and it will still work."

Chang directs a national poll called MyVoice that uses text messages to get opinions and insights from people age 14 to 24 years on a wide range of issues. She and her colleagues have published several reports about young people's attitudes toward COVID-19 and vaccination.

Here's her top 10 list of reasons to get vaccinated before school starts:

1. You'll protect others, and yourself:

Many young people see their role in the pandemic as potential protectors of other people who are more vulnerable to the coronavirus than themselves, according to a MyVoice poll that Chang and colleagues conducted in 2020.

With millions of children under age 12 unable to get vaccinated yet, and millions of adults coping with conditions that might make the vaccine less effective in them, society needs all the 'protectors' it can get.

Every teen and young adult who gets vaccinated helps build a wall of protection around the children and immunocompromised people they know and love. Since one-third of teens who get COVID have no symptoms, an unvaccinated young person can infect many people without even knowing they're infected.

2. It's free, fast and easy to find:

Unlike last spring, when an appointment and a little bit of planning or waiting in line might have been normal, the vaccine is everywhere and you can just walk into a pharmacy, health department or pop-up clinic to get it. Your nearest pharmacy (including ones in grocery stores) probably has it; or find a vaccine location here.

You don't need to pay anything, though if you have health insurance you may be asked to provide your information so your insurance company can pay part of the cost. Bring an ID, and if you're under 18, go with a parent or guardian. (Some locations may accept a letter or phone call from a parent or guardian, and a few states allow people under 18 to get vaccinated without an adult's permission; check first before you go.)

3. Millions of other people your age have already done it:

If you've been waiting to see how other people reacted to the vaccine, the answer is clear: The vaccines have all proven safe and highly effective after eight months of vaccination, and four months of vaccinating younger people.

Cases of COVID-19, hospitalizations and deaths have dropped sharply in places with high vaccination rates. But they remain high in areas where fewer people have gotten vaccinated. The same goes for cases among people of different age groups – as vaccination has gone up, cases have gone down.

That's a clear sign the vaccines are living up to the findings from the tests last year: They offer a high rate of protection.

As of July 19, 35% of people ages 12-15 are at least partly vaccinated, as are 47% of 16- and 17-year-olds and 51% of people ages 18 to 25. If you were waiting to see how it goes, ask a friend, because more than likely they have been vaccinated. Now it's your turn.

Even though you can still catch coronavirus after getting vaccinated, you're likely to have milder symptoms and an extremely low chance of needing hospitalization or dying even if you do become a "breakthrough" case. Out of the 159 million Americans who have been vaccinated by mid-July, only a few thousand breakthrough cases serious enough to need hospitalization have been recorded.

4. You really don't want to get the "Delta variant" of the virus:

It's getting a lot of attention because it spreads faster, which means more people can get sick in a shorter time. That's why some states have suddenly become hotspots of COVID-19 illness and death again.

Even if this strain of coronavirus doesn't make you very sick, you can easily pass it on to others – including people who could get seriously ill or die because they're not vaccinated or their immune system is too weak to get full protection from the vaccine. The vaccines protect you against catching the Delta variant, and other strains of the virus, and that means less chance you'll pass it to others.

5. Summer is a better time to handle any reaction you have to the vaccine:

The relatively relaxed schedules of summer mean that if the vaccine makes you tired or gives you a headache or fever, you can sleep in or rest up.

But you may not have to. Less than 30% of people ages 12 to 15, and about 40% of people ages 16 to 25, said the first dose of vaccine made them tired. That was the most common reaction beside arm pain, according to recently released data from the Centers for Disease Control and Prevention's text-message reaction tracking system. After the second dose, around 50% of the younger group and 60% of the older group felt tired, mostly for a day or so.

In all, only about one in four people ages 12 to 25 said that they couldn't do normal activities for a day or so in the first week after vaccination.

If you work, figure on a one-in-six chance of having to miss work the day after you get your second dose of an mRNA vaccine, or your single dose of the one-dose vaccine.

Chang advises patients to get vaccinated in the late afternoon or evening before a day off. That way, if you do feel tired, or get a headache or fever, it's most likely to start the next morning and be done later that day.

6. There's been time to look for rare but serious effects, and there are only a few:

Now that hundreds of millions of doses have gone into arms, a few rare, but more serious issues, have been detected, thanks to doctors and others who reported them to the nation's "early warning system" for vaccine-related issues.

Just over 1,200 people, most of them under age 30, have experienced brief heart muscle inflammation after a dose of the two-dose vaccines. It is easily treated and now doctors are on the lookout for it.

Similarly, a few dozen people have had a rare form of blood clotting, which is also very treatable, after getting the J&J vaccine; doctors have also gotten an alert to look out for it, especially in younger women.

About 100 of the 12.8 million people who have gotten the J&J vaccine have developed Guillain-Barré Syndrome, an immune system attack on nerves. Most were men over 50 who were two weeks out from vaccination.

There's a lot of misinformation about other "side effects" of the vaccines online – so much that the Surgeon General has issued a statement warning about it. Don't be tricked! You should use trusted sources – including your own physician or other health provider – to ask questions and get information about anything you've heard.

7. You won't have to mask up as often:

Experts are recommending mask use inside classrooms, even for vaccinated people, when school starts up again, because of the rise of the Delta variant and the lag in vaccination rates in some states.

But other places – stores, offices, stadiums, concert arenas, movie theaters, and more – have made masks optional for people who are fully vaccinated. That's because the vaccine greatly lowers the chances that someone will get infected and pass the virus to others who are vulnerable. And masks in general aren't needed outdoors.

Of course, even if it's not required in your school or college, you have the right to wear a mask anywhere you want, to give yourself and the people you live with that extra level of protection against catching the virus.

No matter what your vaccination status, you'll still need to wear a mask in health care and transportation settings, and in any privately-owned establishment that requires masks.

8. You could win a prize, but only if you act now:

Several states, and many pharmacy chains, have announced that people who get vaccinated by the end of July will be eligible for special lotteries or prizes, including cash, college scholarships and chances to win trips. You may have to fill out a registration form online, and deadlines are coming up! 

The free giveaways that various restaurants and stores have been doing for people who show their vaccination card are also ending. Don't miss out on your chance to get that free snack or drink.

SEE ALSO: On the Fence about the COVID-19 Vaccines?

9. You can travel and attend major events:

Canada just announced that Americans who can show proof of vaccination will be able to enter for any reason starting August 9, and other countries are opening their borders too. Broadway theaters and other venues are asking for proof of vaccination in order to attend shows mask-free.

While the United States hasn't adopted a "vaccine passport" standard, businesses and other countries are allowed to require proof of vaccination for entry or going maskless.

10. We can get back to normal life:

The more people are vaccinated, the more likely events we have all missed this past year can safely happen again — trying a new restaurant, sleepovers, birthday parties, family reunions, proms, graduations.

"We all want to get back to "normal," but it won't happen on its own," Chang said. "Everyone who can should get vaccinated to stop the spread and to prevent further strains from developing. We've had to give up so much in the past year. Let's take action now so we don't miss out on more."