For some local travelers looking for a vacation, the question is not whether to book a vacation this year, but when.

The enthusiasm for travel is at its highest level in a year. According to a survey conducted last week by travel market research firm Destination Analysts, 87% of American travelers are expected to take a trip this summer.

But is summer the best time to go this year or is it advisable to wait? Doctors present various scenarios of how the rest of 2021 could develop.

1. A summer with low infection rates

Dr. Sharon Nachman, director of pediatric infectious diseases at Stony Brook Children’s Hospital, expects infection rates to be lower this summer than in winter.

“If I add the idea that children 12 and older also have access to vaccines this summer, the risk for families will continue to decrease, allowing more activity and less risk for everyone,” she said.

Dr. Anne Rimoin, professor of epidemiology at UCLA Fielding School of Public Health, said there was “a real chance for a summer with much lower disease rates. But that means we must all pull ourselves together and do our best.” Part “through vaccination, wearing masks, social distancing and hand hygiene.

Vaccinations are important for a safe summer trip, said Dr. Anne Rimoin of UCLA Fielding School of Public Health, despite finding they are “no guarantees” against infection.

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Whether it is safe to travel this summer depends on two factors: vaccinations and variants.

“It all depends on how many vaccines we get our arms about,” said Rimoin. “The variants are more contagious, so … those who aren’t vaccinated are more likely to get infected.”

2. A good summer and a mild autumn

Former Food and Drug Administration commissioner Scott Gottlieb told CNBC’s “Squawk Box” in April that he expected US infection rates to be “really low” this summer, likely leading to a “relatively mild decline” will lead.

Things might change after that, he said.

We’ll have to do things differently when we get into winter.

Scott Gottlieb

Former FDA commissioner

“I think we should think about late winter,” he said. “I think the overall death and disease from Covid will hopefully be reduced, but there is a chance they could spread again.”

Gottlieb said Covid-19 will “move from a more pandemic to a seasonal burden this year”. However, that could change if variants develop that can “penetrate” a previous immunity or vaccine, although he noted that “that’s not on the horizon right now.”

“I don’t think we’re going to be having Christmas parties on December 20th in the back room of a crowded restaurant,” he said. “I think we have to do things differently when we come into winter.”

“But I think that will be a fact for a few years,” said Gottlieb.

3. Flares and outbursts

Dr. Charles Bailey, medical director of infection prevention at Providence St. Joseph Hospital and Providence Mission Hospital, doesn’t see this summer as a safe time to travel before infections return in the fall as he expects the outbreaks to continue year round.

He anticipates the majority of the United States will continue on its path to normal while the areas will experience “episodic flare-ups – local and regional” hotspots “- of Covid activity by late 2021 and early 2022.”

Mark Cameron, epidemiologist and associate professor in the School of Medicine at Case Western Reserve University, does not see summer as a “window of opportunity for perfectly safe travel itself,” as he has concerns about last summer’s waves and the possibility of a variant Fuel has bursts.

He compared the current state of the pandemic to “watching the tick and drying an irregular clock pendulum”.

“The pandemic could cause the virus to circulate unpredictably and new variants could cause outbreaks or epidemics on a regular basis, especially if vaccine availability is low or vaccine hesitation is high, similar to what is happening now with the flu,” Cameron said .

“The moment we are in – with vaccination rates, variant spread and Covid-19 fatigue in competition – is vital to stop this virus and its growing penchant for evading our eradication efforts,” he said.

4. The chance of another summer climb

William Haseltine, former professor at Harvard Medical School and author of “Variants! The Shape-Shifting Challenge of COVID-19,” said there was a risk of another summer surge and summer travel would only make the problem worse.

“The more people choose to escape the very real pandemic stress and fatigue, the more we risk another spike in cases this summer,” he said.

Covid-19 is expected to become a seasonal disease at some point, but it is not known when this will occur.

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Haseltine said many people hope that warm summer weather will lead to a decline in Covid cases due to the seasonality of other coronaviruses and influenza viruses.

But as it turns out, this virus is “far less seasonal than many expect,” he said. “If you look back on 2020 and the early part of 2021, you will find that, as expected, there have been falls and winter flare-ups, but also spring and summer flare-ups.”

While the virus that causes Covid-19 is expected to become seasonal at some point, the United Nations World Meteorological Organization has highlighted in a report that “there is no evidence” that this year will be different from 2020.

Read more about summer travel in the age of Covid

Dr. Supriya Narasimhan, chief infectious disease surgeon at Santa Clara Valley Medical Center, agreed that another spike is possible in the summer, even in places where vaccines are being aggressively introduced.

She agreed that Covid is “less seasonal than the flu” and said the factors that will influence whether it will continue to rise are public adherence to masking, vaccine intake and variants.

“It’s a game of cat and mouse where the virus mutates. The only way to stop it is to stop transmission,” she said. “We might still hit a vaccine wall because people just don’t want to take it, even if it’s available.”

“I think we need more data to make travel decisions,” she said.

Disclosure: Scott Gottlieb is a CNBC employee and a member of the boards of directors of Pfizer, genetic testing startup Tempus, health technology company Aetion Inc., and biotech company Illumina. He is also co-chair of the Healthy Sail Panel for Norwegian Cruise Line Holdings and Royal Caribbean.