NEW YORK • Even with Covid-19 vaccines on the way, many epidemiologists do not expect their lives to return to pre-pandemic normal until most Americans have been vaccinated.

In the meantime, most have eased up on some precautions - going to the grocery store or seeing friends outdoors, for example - but are as cautious as ever about many activities of daily life.

In a new informal survey of 700 epidemiologists by The New York Times (NYT), half said they would not change their personal behaviour until at least 70 per cent of the population was vaccinated. Thirty per cent said they would make some changes once they were vaccinated themselves.

A minority of the epidemiologists said if highly effective vaccines were widely distributed, it would be safe for Americans to begin living more freely this summer.

Michigan State University assistant professor Kelly Strutz said: "I am optimistic that the encouraging vaccine results mean we'll be back on track by or during summer 2021."

But most said that even with vaccines, it would probably take a year or more for many activities to safely restart and that some parts of their lives may never return to the way they were.

UCLA professor of epidemiology Karin Michels said it would probably be many years until it was safe enough to "return to approximately the lifestyle we had".

PRE-PANDEMIC LIFE

Of 23 activities of daily life that the survey asked about, there were only three that the majority of respondents had done in the past month: gathering outdoors with friends; bringing in mail without precautions; and running errands, like going to the grocery store or pharmacy.

The epidemiologists have almost entirely avoided other parts of pre-pandemic life. Almost none said they had attended a sporting event, play or concert; met up with someone they did not know well; or attended a wedding or funeral.

"Being in close proximity to people I don't know will always feel less safe than it used to," said Dr Ellicott Matthay, a postdoctoral scholar at the University of California, San Francisco.

Three-quarters of respondents said they planned to spend Christmas, Hanukkah or other winter holidays with only members of their household, or not celebrate at all, similar to how they spent Thanksgiving.

When asked about the safest and riskiest activities on the list, most epidemiologists agreed on these general principles: They are less worried about outdoor activities and about touching surfaces, and more worried about indoor activities and those with large groups.

But even the epidemiologists did not all agree on their assessment of risk.

"Indoor venues with lots of people is the riskiest situation," said Dr Leland Ackerson of the University of Massachusetts. "Outdoors with few people, social distancing and precautions is the least risky."

He said that during the past month, he had hiked with friends, opened mail without precautions and run errands.

Six months ago, NYT asked a similar group of epidemiologists about when life might go back to normal.

Most then guessed that people would need to wait a year or more for many aspects of daily life to normalise.

HERD IMMUNITY

This time, as the spread of the virus has worsened but the treatments have improved, NYT focused its questions on how they have been living in the thick of the pandemic.

"It's funny - when asked this before, I was so optimistic about the US being able to lead and address this in a timely fashion," said University of Minnesota associate professor Rachel Widome.

"I said I thought things would be better by now. I was very wrong. They are dramatically worse."

Most scientists say around 70 per cent of the population will need to be immune for the United States to reach herd immunity, when the virus slows down significantly or stops. Herd immunity is crucial, they say, for people to safely resume many parts of life, and the fastest and safest way to achieve it is through vaccination.

Dr Moncef Slaoui, who is leading the government's Operation Warp Speed vaccine development programme, said vaccines may roll out quickly enough for the US to reach herd immunity by early summer.

But scientists do not yet know if vaccinated people could still spread the virus.

Nearly a third of respondents said they would be comfortable returning to more activities of daily life once they were vaccinated.

Some said they would feel comfortable doing only certain things, like socialising with people who had also been vaccinated.

"I would do some minimal travel, small indoor gatherings with other close relatives when I am vaccinated, but maintain safety precautions such as wearing a mask and socially distance," said Dr Gabriela Vazquez Benitez, a senior research investigator at HealthPartners Institute, a non-profit group.

NYTIMES