Analysis: Time for a long-term antivirus strategy

The coronavirus crisis is a long way from being over. And because life on permanent lockdown isn’t sustainable, public health experts are beginning to embrace a “harm reduction” approach, giving people alternatives to strict quarantine.

These options – like forming a “bubble” with another household or moving social activities outdoors – don’t eliminate risk, but they minimise it as people try to return to daily life.

Nobody knows exactly what will happen as communities open up. The most likely scenario is that virus cases will continue to surge and fall around the globe for the foreseeable future.

“It’s hard to imagine how we will avoid another surge in infections, which is why these harm reduction approaches that keep people away from much higher risk situations are so important,” said Julia Marcus, an infectious disease epidemiologist and assistant professor in the department of population medicine at Harvard Medical School.

“If someone expanding their bubble keeps them from having crowded dinner parties or going to bars, then that is a success.”
While we’ve learned to live with masks and social distancing, as well as new rituals of hand-washing, we need some basic rules to minimise risk and still have a life going forward.

We’ve consulted public health experts and scientists to give you the tools you need to make your own decisions, whether it’s dining at a restaurant, going to church or simply getting a haircut.

1. Check the health of your community

To gauge your risk of coming into contact with an infected person, pay attention to two important indicators of Covid-19 in your area: the percentage of tests that are positive, and the trend in overall case rates.

2. Limit the number of your close contacts

You’re safest with members of your household, but if you want to widen your circle to extended family or friends, keep the number of close contacts as low and as consistent as possible.

One way to do this is to form a “corona bubble”, which happens when two households form an exclusive social circle, agreeing on safety guidelines and to see only each other. The arrangement allows people to visit each other’s homes and lead a somewhat normal, if limited, social life. It may be particularly helpful for families with similar structures, such as those with young children longing for playmates or teenagers seeking in-person contact.

The arrangement requires a high level of trust. How does each family define reasonable precautions? Count the number of potential “leaks” for each member of the bubble, such as trips to the store or office, play dates, children and teens who see friends, or housekeepers and nannies who may visit multiple homes.

Keep communication open and without judgment, so people feel comfortable disclosing new exposure risks and potential “leaks” in the bubble. “People’s activities are going to change every day: schools may reopen, someone may decide to go to protest,” said Marcus. “This is not just a one-time agreement. The communication about risk needs to be ongoing and open.”

3. Manage your exposure budget

Risk is cumulative. You will need to make trade-offs, choosing activities that are most important to you (like seeing an aging parent) and skipping things that might matter less (an office going-away party).

Think about managing virus risk just as you might manage a diet: if you want dessert, eat a little less for dinner.

During a pandemic, every member of the household should manage their own exposure budget. (Think Weight Watchers points for virus risk.)

You spend very few budget points for low-risk choices like a once-a-week grocery trip or exercising outdoors.

You spend more budget points when you attend an indoor dinner party, get a haircut or go to the office. You blow your budget completely if you spend time in a crowd.

“Moving into a long-term management phase, we have to start thinking like this,” says Johannes Eichstaedt, a computational social scientist and psychology professor at Stanford University.

“Don’t take risks where it’s not needed and make trade-offs that are congruent with your larger health needs and priorities.

“If seeing my grandchild in the park means, to balance this, I can only go to the supermarket every other week, maybe that’s a trade-off I’m willing to make for my mental health and well-being.”

Unfortunately, there’s no magic number to determine your personal exposure budget and the exposure “costs” of different actions. But think about your overall exposure budget when you make decisions to spend time with other people, particularly older people and those with high-risk conditions.

4. Keep higher risk activities as short as possible

Every time you make plans, ask yourself: “If an infected person happens to be nearby, how much time could I be spending with them?” It takes an extended period of close contact with an infected person, or extended time in a poorly ventilated room with an infected person, to have a substantial risk of catching the virus through the air, said Linsey Marr, an aerosol scientist at Virginia Tech.

When making decisions, keep indoor events brief and move social events outdoors. Wear a mask and practise social distancing. Here’s some guidance about time of exposure.

Brief exposure: Brief encounters, particularly those outside – like passing someone on the sidewalk or a runner who huffs and puffs past your picnic – are unlikely to make you sick.

Face-to-face contact: Wear a mask, and keep close conversations short. We don’t know the level of exposure required to make you sick, but estimates range from a few hundred to 1 000 copies of the virus. In theory, you might reach the higher estimate after just five minutes of close conversation, given that a person might expel 200 viral particles a minute through speech. When health of,ficials perform contact tracing, they typically look for people with whom you’ve spent at least 15 minutes in close contact.

Indoor exposure: In an enclosed space, like an office, restaurant or in a church, you can still become infected from a person across the room if you share the same air for an extended period of time. There’s no proven time limit that is safest but based on contact tracing guidelines and the average rate at which we expel viral particles – through breathing, speaking and coughing – it’s best to keep indoor activities, like shopping or haircuts, to less than an hour. Even shorter is better.

As you make decisions, Bromage suggests considering the volume of air space (open space is safer than a small room), the number of people in the space and how much time everyone is together (keep it brief).
To learn more about timing and risk, read Bromage’s blog post on the topic, which has been viewed more than 18 million times.

5. Keep taking precautions

Already some people in many communities have stopped wearing masks, suspended social distancing and returned to their pre-pandemic socialising. Time will tell if case counts start to rise as a result but in the coming months, you would be wise to adopt the following habits.

• Keep a mask handy. Wear a mask in enclosed spaces, to go to the shop or the office and when in close contact with people outside your household.
• Practise social distancing – stay 1.8m apart when you are with people outside your household. Keep social activities outdoors.
• Wash hands frequently, and be mindful about touching public surfaces (elevator buttons, hand rails, subway poles, and other high-touch areas).
• Adopt stricter quarantine practices if someone in your circle is at higher risk.

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