How Do You Stay Safe Now That States Are Reopening?
By Ryan Malosh
Editor's note: Now that states are relaxing social distancing restrictions, people desperately want to see friends and family, go to a restaurant and let our kids have playdates. Even grocery shopping sounds fun. But how can you do that and still stay safe? Here, an epidemiologist who is immune-compromised himself walks you through some decision-making.
The Centers for Disease Control and Prevention has finally released new guidelines for businesses, bars and schools that are considering reopening. Although following these guidelines should help, it's frustrating there hasn't been more clear, concise communication about the risk of infection. And without strict guidelines, it will be up to us to minimize our own risk and the risk of everyone around us.
In large part, this is because there is still so much we scientists and physicians don't know about the new coronavirus. The pace of new research on the virus, SARS-CoV-2, and the disease it causes, COVID-19, is truly astonishing. There are also times when the science and the necessity of the moment are in conflict; a prime example is the confusion about using face masks while a worldwide shortage of personal protective equipment exists.
And the pattern of disease is extremely localized. Michigan's outbreak looks different from Iowa's, which looks different from Colorado's. Even within states, outbreaks are very distinct. The outbreak I'm experiencing in southeast Michigan is not like the one my grandparents are experiencing two hours north of here. As a research scientist, I study herd immunity and vaccine effectiveness. As we slowly begin to return to normal life – albeit a new normal – I can tell you there are ways we can minimize our risk.
As a survivor of leukemia and a bone marrow transplant, I am part of a high-risk population, so my risk calculation is likely different from yours. As my state starts to relax restrictions, I will continue to limit my interactions with others as much as I can. Here are things you can consider.
What’s Associated With a High Risk of Transmission?
How SARS-CoV-2 transmits from person to person is still a mystery. It can certainly be transmitted by large respiratory droplets, like those produced when we cough or sneeze. Evidence also suggests that smaller aerosol particles, spread while talking or breathing, can lead to transmission. There is some evidence that people can transmit the virus before they have symptoms, although they will likely have the highest amount of virus close to the start of the illness.
Taking all this together, it's safe to say the riskiest thing you can do is to come into close contact with sick people. That's why the advice about self-isolation if you feel ill is so important.
It's also becoming clear the virus transmits most effectively in indoor settings. There, close contact between infected people and inadequate ventilation are more likely. The infection risk is especially high among household contacts. Efficient transmission in crowded, enclosed spaces also explains the high attack rates in nursing homes, food processing plants, jails and prisons and cruise ships. On the flip side, the risk of transmission does seem to be lower outdoors.
How Do We Minimize Risk?
If the riskiest thing is to be in a crowd while indoors with sick people, then it follows the least risky behavior is to be in small groups, outdoors and to avoid sick people.
I think it will help to describe a simple model of infectious disease. The rate of new infections over a given time period is called the "force of infection," which depends on a few things: the rate at which people contact each other; the probability of infection given contact; and the number of infectious individuals in a population.
This means our ability to prevent new infections depends on two things: reducing the rate at which people contact each other – or reducing the probability of infection given contact.
Reducing the contact rate was the goal of stay-at-home measures. By all accounts, this is still the most effective tool to prevent new infections.
Other nonpharmaceutical interventions, like face masks and hand hygiene, reduce the effective contact, or the chance the virus is transmitted if there is contact. Universal masking may be particularly effective if we can't rely on symptomatic screening for identifying infectious cases.
Or maybe you've heard of the layers of Swiss cheese. Sometimes you have a few interventions (slices of Swiss cheese), but none is perfect (the holes). But stack the slices up, and the holes start to cover up. Layering imperfect interventions can, in a similar way, slow down transmission.
So What Does It All Mean?
I once read a quote about the common cold from Ian Mackay, an Australian virologist: "The only fail-safe means of avoiding a cold is to live in complete isolation from the rest of humanity." The same is probably true for COVID-19.
But that's not realistic. Authorities should borrow ideas from HIV prevention and focus on clear messages for harm reduction. In the absence of stay-at-home orders, all of us will have to decide for ourselves how much risk we are willing to tolerate.
I'm a leukemia survivor, so I will factor that in. You, too, will need to consider your medical history. When I'm not in isolation, I will stack as many layers of Swiss cheese as I can to minimize any risk: staying 6-10 feet away from others, wearing masks, staying outdoors.
I think these are generally common-sense guidelines for anyone.
- If your local authorities allow small gatherings, then getting together with friends who aren't sick or who haven't been in contact with other sick people is safest outdoors.
- Try to stay as far apart from each other as you can.
- Keep a mask and hand sanitizer nearby.
- Don't share food or drinks.
- If anyone feels sick or has had recent contact with someone who feels sick, they should skip the playdate (this goes for adults and kids).
- If you are seeing someone at high risk of severe disease, an older relative or someone with a compromised immune system, take even more precautions and consider whether you can connect with them virtually.
Ryan Malosh is an Assistant Research Scientist at the University of Michigan.
Disclosure statement: Ryan Malosh receives salary support from the Centers for Disease Control and Prevention (CDC) and the National Institute for Allergy and Infectious Disease (NIAID).
Reposted with permission from The Conversation.
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By Joni Sweet
If you get a call from a number you don't recognize, don't hit decline — it might be a contact tracer calling to let you know that someone you've been near has tested positive for the coronavirus.
Interviews With Contact Tracers<p>Contact tracing is a public health strategy that involves identifying everyone who may have been in contact with a person who has the coronavirus. Contact tracers collect information and provide guidance to help contain the transmission of disease.</p><p>It's been used during outbreaks of sexually transmitted infections (STIs), Ebola, measles, and now the coronavirus that causes COVID-19.</p><p>It starts when the local department of health gets a report of a confirmed case of the coronavirus in its community and gives that person a call. The contact tracer usually provides information on how to isolate and when to get treatment, then tries to figure out who else the person may have exposed.</p><p>"We ask who they've been in contact with in the 48 hours prior to symptom onset, or 2 days before the date of their positive test if they don't have symptoms," said <a href="https://case.edu/medicine/healthintegration/people/heidi-gullett" target="_blank">Dr. Heidi Gullett</a>, associate director of the Center for Community Health Integration at the Case Western Reserve University School of Medicine and medical director of the Cuyahoga County Board of Health in Ohio.</p>
“You’ve Been Exposed”<p>After the case interview, contact tracers will get to work calling the folks who may have been exposed to the coronavirus by the person who tested positive.</p><p>"We give them recommendations about quarantining or isolating, getting tested, and what to do if they become sick. If they're not already sick, we still want them to self-quarantine so that they don't spread the disease to anyone else if they were to become sick," said Labus.</p><p>Generally, the contact tracer won't ask for additional contacts unless they happen to call someone who is sick or has a confirmed case of the virus. They will help ensure the contact has the resources they need to isolate themselves, if necessary. The contact tracer may continue to stay in touch with that person over the next 14 days.</p><p>"We follow the percentage of people that were contacts, then converted into being actual cases of the virus. It's an important marker to help us understand what kind of transmission happens in our community and how to control the virus," said Gullett.</p>
Why You Should Participate (and What Happens If You Don’t)<p>A <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30457-6/fulltext" target="_blank">Lancet study</a> from June 16, which looked at data from more than 40,000 people, found that COVID-19 transmission could be reduced by 64 percent through isolating those who have the coronavirus, quarantining their household, and contacting the people they may have exposed.</p><p>The combination strategy was significantly more effective than mass random testing or just isolating the sick person and members of their household.</p><p>However, contact tracing is only as effective as people's willingness to participate, and a small number of people who've contracted the coronavirus or were potentially exposed are reluctant to talk.</p><p>"Contact tracers have all been hung up on, cussed at, yelled at," said Gullet.</p><p>The hesitation to talk to contact tracers often stems from concerns over privacy — a serious issue in healthcare.</p>
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By James Shulmeister
Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.
If you have a question you'd like an expert to answer, please send it to firstname.lastname@example.org
What was the climate and sea level like at times in Earth’s history when carbon dioxide in the atmosphere was at 400ppm?<p>The last time global carbon dioxide levels were consistently at or above 400 parts per million (ppm) was around <a href="https://www.nature.com/articles/nature14145" target="_blank">four million years ago</a> during a geological period known as the <a href="http://www.geologypage.com/2014/05/pliocene-epoch.html" target="_blank">Pliocene Era</a> (between 5.3 million and 2.6 million years ago). The world was about 3℃ warmer and sea levels were higher than today.</p><p>We know how much carbon dioxide the atmosphere contained in the past by studying ice cores from Greenland and Antarctica. As compacted snow gradually changes to ice, it traps air in bubbles that contain <a href="https://www.cambridge.org/core/journals/annals-of-glaciology/article/enclosure-of-air-during-metamorphosis-of-dry-firn-to-ice/09D9C60A8DA412D16645E6E6ABC1892F" target="_blank">samples of the atmosphere at the time</a>. We can sample ice cores to reconstruct past concentrations of carbon dioxide, but this record only takes us back about a million years.</p><p>Beyond a million years, we don't have any direct measurements of the composition of ancient atmospheres, but we can use several methods to estimate past levels of carbon dioxide. One method uses the relationship between plant pores, known as stomata, that regulate gas exchange in and out of the plant. The density of these stomata is <a href="https://journals.sagepub.com/doi/abs/10.1177/095968369200200109" target="_blank">related to atmospheric carbon dioxide</a>, and fossil plants are a good indicator of concentrations in the past.</p><p>Another technique is to examine sediment cores from the ocean floor. The sediments build up year after year as the bodies and shells of dead plankton and other organisms rain down on the seafloor. We can use isotopes (chemically identical atoms that differ only in atomic weight) of boron taken from the shells of the dead plankton to reconstruct changes in the acidity of seawater. From this we can work out the level of carbon dioxide in the ocean.</p><p>The data from four-million-year-old sediments suggest that <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010PA002055" target="_blank">carbon dioxide was at 400ppm back then</a>.</p>
Sea Levels and Changes in Antarctica<p>During colder periods in Earth's history, ice caps and glaciers grow and sea levels drop. In the recent geological past, during the most recent ice age about 20,000 years ago, sea levels were at least <a href="https://science.sciencemag.org/content/292/5517/679.abstract" target="_blank">120 meters lower</a> than they are today.</p><p><span></span>Sea-level changes are calculated from changes in isotopes of oxygen in the shells of marine organisms. For the Pliocene Era, <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2004PA001071" target="_blank">research</a> shows the sea-level change between cooler and warmer periods was around 30-40 meters and sea level was higher than today. Also during the Pliocene, we know the West Antarctic Ice Sheet was <a href="https://www.nature.com/articles/nature07867" target="_blank">significantly smaller</a> and global average temperatures were about 3℃ warmer than today. Summer temperatures in high northern latitudes were up to 14℃ warmer.</p><p>This may seem like a lot but modern observations show strong <a href="https://journals.ametsoc.org/jcli/article/23/14/3888/32547" target="_blank">polar amplification</a> of warming: a 1℃ increase at the equator may raise temperatures at the poles by 6-7℃. It is one of the reasons why Arctic sea ice is disappearing.</p>
Impacts in New Zealand and Australia<p>In the Australian region, there was no Great Barrier Reef, but there may have been <a href="https://link.springer.com/content/pdf/10.1007/BF02537376.pdf" target="_blank">smaller reefs along the northeast coast of Australia</a>. For New Zealand, the partial melting of the West Antarctic Ice Sheet is probably the most critical point.</p><p>One of the key features of New Zealand's current climate is that Antarctica is cut off from global circulation during the winter because of the big <a href="https://www.tandfonline.com/doi/abs/10.3402/tellusa.v54i5.12161" target="_blank">temperature contrast</a> between Antarctica and the Southern Ocean. When it comes back into circulation in springtime, New Zealand gets strong storms. Stormier winters and significantly warmer summers were likely in the mid-Pliocene because of a weaker polar vortex and a warmer Antarctica.</p><p>It will take more than a few years or decades of carbon dioxide concentrations at 400ppm to trigger a significant shrinking of the West Antarctic Ice Sheet. But recent studies show that <a href="http://nora.nerc.ac.uk/id/eprint/521027/" target="_blank">West Antarctica is already melting</a>.</p><p>Sea-level rise from a partial melting of West Antarctica could easily exceed a meter or more by 2100. In fact, if the whole of the West Antarctic melted it could <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.695.7239&rep=rep1&type=pdf" target="_blank">raise sea levels by about 3.5 meters</a>. Even smaller increases raise the risk of <a href="https://www.pce.parliament.nz/publications/preparing-new-zealand-for-rising-seas-certainty-and-uncertainty" target="_blank">flooding in low-lying cities</a> including Auckland, Christchurch and Wellington.</p>
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