All Your COVID-19 Questions, Answered

When the COVID-19 pandemic started, most of us did everything we could to lower our risk of getting infected. We locked ourselves in our homes. We limited our contact with other people. We became obsessive about hygiene, wearing surgical masks, and washing our hands with the frequency and vigor of a first-year medical resident. What made it palatable, in large part, was the feeling that it was only temporary. We'd lock down, and then after a few weeks, or a couple of months at the most, things would reopen and we could get back to normal.

That, as we all know, hasn't happened. The virus operates on its own schedule. Without a vaccine, it is now clear, we'll be living with COVID-19 for the foreseeable future; even the most optimistic estimates for a vaccine are early 2021. So the question now is: How do we operate in a world where even the most mundane decisions - whether to meet a friend for a drink, say, or to pop into the corner grocery for a pint of Hӓagen-Dazs - can feel like matters of life or death?

I'm an economist, a discipline in which we are endlessly analyzing how risk and uncertainty factor into everyday life. How do people approach the stock market in times of economic crisis? What motivates someone to wear a seat belt, or take a dangerous job, or skip the insurance option when renting a car? Economists look at data on these behaviors to try to figure out what "value" people implicitly put on their lives.

Today, in the midst of a global pandemic, we face an unprecedented level of risk and uncertainty in our daily lives - with very little reliable information to guide us. Our political leaders have been at best inconsistent, and at worst flat-out wrong, when it comes to communicating how to protect ourselves and each other.

As is often the case, small things can make a huge difference. Just as you wouldn't drive your car without your seat belt or go skydiving without a parachute, you should wash your hands and wear a mask whenever you go out. But even if we take such precautions, we face some risk of COVID-19 every time we leave our homes. The question to ask is: How large is that risk, and is it worth it? To help make sense of all the confusing and often contradictory advice, I consulted more than a dozen doctors and scientists and tried to sort out the most logical, rational, simple advice science could offer to just about every question imaginable.

How much riskier does having a comorbidity make all of the decisions I make on a daily basis? Is it a multiplier?
Comorbidities matter, seemingly a lot. A recent article in The Lancet looked at risks for mortality by other illnesses. The more risk factors people have - especially from lung, kidney, and heart disease - the higher their mortality rates. People between the ages of 30 and 55 with three or more comorbidities, the study found, are up to nine times as likely to die as those with only one. So yes, chronic illness is a significant multiplier.

Even in a half-full restaurant, your exposure to other people is greater - more people may touch your plate, for example, and they may breathe on you. If you take good precautions, though, the risk is still low - but not as low as grocery shopping.

Do I need to think about what I order at a restaurant? Is hot food safer than cold food?
There's no evidence that COVID-19 is contracted from food - hot or cold. If someone who is infected sneezes on your food, it could make you sick. But if you eat at places with good hygiene practices, this shouldn't happen. So feel free to eat salad.

There are a bunch of things to consider ( see some details here), including how far you can be from other people, how hard you'll be breathing, and what the airflow is like. But the bottom line is that the safest gym activities are low impact, non-heavy-breathing things like yoga. The riskiest are things like Zumba, where you're breathing heavily in a poorly ventilated room with others.

Oh, and if you can be outdoors: better. Try an outdoor exercise class if you can find one.

But the virus spreads less outdoors. This is very clear in the data; "super-spreader" events seem to be confined largely to indoor activities.

Think about it like this: The worst case is someone with COVID-19 coughs right in your face and tons of virus particles get on you. Now let's say you are in a store and near someone and they cough. The air is fairly still, so some virus particles may get to you. Lower odds, but still potentially bad. If you're outside, air movement disrupts the path from the other person's face to you, meaning fewer droplets get to your face. Plus, if you're outside, it's easier to distance from people, since there's more space.

But in New York City, it's impossible to go for a walk and stay six feet apart from other people. Does that mean I shouldn't go outside unless I have an essential errand?It's worth noting that the Centers for Disease Control and Prevention defines "close contact" as being within six feet of someone who has tested positive for more than 15 minutes without a mask. And if you dig into the way the virus works (more here), it's clear that the risk of getting the virus from someone just in passing them on the street is really, really tiny.

A second obvious question is whether they are feeling sick. But since more than half of all transmissions are from asymptomatic or presymptomatic people, it's probably not all that helpful a question to ask. A simpler approach would be to come over with your own food and to sit outside in a distanced way.

We want to create a pod with another family to get in some more socializing. What are good "pod"rules of engagement?
The key here is having an up-front conversation with them to align your risks and expectations. Are they going out of the house to work? Are they wearing masks when grocery shopping? Have you all been quarantined? Kids playing together outside is much less risky than a pod where adults get together indoors.

Getting tested could be helpful, but keep the incubation period in mind. If he's tested the day he comes back, that would pick up any infection from his trip, but probably not from the flight home. If you have time, a reasonable approach would be a seven-day quarantine period with a test on day five, hopefully returned by day seven. Then, enjoy the beach.

There is a particular UV wavelength - UVC light - that kills viruses like this really effectively, even in the air. But this particular wavelength is incredibly dangerous to people: It can give you an awful sunburn in seconds. There is some suggestion that another version of UVC light may be safer for people and still kill viruses, but this isn't a workable solution yet.

Whether that's in the same trip or a different trip is irrelevant. Same goes for friends. If you see one friend, the risk of adding one more is the same as if you saw them separately. Also friends and stores. The friend is risky; the store is risky. Add the risks! Waiting outside is less risky because you are removing the store risk.

The bottom line is your best bet is to limit the risks of each of these things individually by wearing masks and maintaining distance, rather than to try to game the system by combining them.

You're probably at greater risk if you live in an apartment building, where surfaces aren't cleaned regularly. Be careful with doorknobs and elevators. Use a tissue to touch them and then throw it away. It also helps to wash your hands a lot and wear a mask in public areas.

When you say the virus can live for a short time on surfaces, how short are we talking
This is an easy question to study in the lab. We got an answer early on in the epidemic: a few days on plastic and steel, 24 hours on cardboard, a shorter time on copper. However, that was in lab conditions,which are optimized for virus growth and survival - unlike, say, your Amazon package sitting outside in the humidity. In general, the real length of time for survival on surfaces like takeout bags and packages appears to be quite small. Infectious viruses don't like to be on dry stuff. They prefer liquidy cells, which they need to replicate and grow.

Can public transit be managed in a way that makes it a safe option?Probably not perfectly safe. If everyone wears masks, maintains some physical distance, and washes or sanitizes their hands after touching common surfaces, then it should be safer - at least for passengers. Unfortunately, data from Sweden shows that bus driving ranks among the most high-risk occupations. The fact is it's going to be hard to increase safety on public transit; a bike is still going to be a better option whenever possible. And avoid eating on public transit owing to the high chance of touching surfaces before touching your mouth.

A lot of people I know are starting to get tested for the virus. But what's the point if I can contract it in a crowded supermarket the day after I test negative? We can't all keep getting tested over and over again.You are completely right that testing only tells you what is going on at the moment of the test. And if people respond to a negative test by thinking, Great, now I can do whatever I want, it's likely to be counterproductive.

But in a way, that's really an argument for more testing, not less. In a magical, ideal world, we'd all be tested every day. That kind of surveillance testing - repeated testing among people even without symptoms - would enable us to control the virus. Even if everyone was tested every couple of weeks, it would serve as an early warning system to catch a lot of infections before they spread as widely. That's especially true given that a large share of infections are asymptomatic.

Many universities that are thinking about reopening this fall are planning to do surveillance testing. And a number of places are starting to do systematic testing among groups like child-care workers, hairstylists, and those who work in retail. Europe has been doing some of this with schoolchildren as well.

Can testing help me know where it's safest to travel? It seems hard to compare state trends when everyone is handling testing very differently. We can do some comparison of state trends even in the absence of perfect data. The best testing and tracking data is here, at Johns Hopkins. They report the number of tests and the share of tests that are positive, among other things.

A lot of people (notably the president) have observed that emphasizing the number of positive tests isn't quite right, since the more tests we do, the more cases we see. That's why I tend to focus on the share of tests that are positive, as well as the trend over time. If a state is doing roughly the same number of tests each day, you can get some sense of the epidemic by looking at the share of positive tests. Even states that initially had pretty poor testing regimes are improving at this point. So when we see the share of positive tests going way, way up in places like Arizona and Florida, we should read this as evidence that the epidemic is worsening there.

Which states just aren't testing enough to even have a clear picture?Again, I'd reference Johns Hopkins. I'm worried about states that have a low testing rate and a high positive rate. As I'm writing this, Kansas has among the lowest testing rates (1.4 tests per 1,000 people) and a high positive rate (10.9 percent). By contrast, Washington, D.C., is doing 4.6 tests per 1,000 people with a positive rate of only 1.7 percent.

I worry also about places like Arizona, where nearly a quarter of people tested are positive. This points to not enough testing for where they are in the epidemic.

If you go in for a test to see if you have the virus right now, you'll likely get a PCR test, which involves a nasal or throat swab. The swab full of mucus is sent to a lab, or possibly tested in a machine on the spot, to look for the presence of the virus. This type of testing rarely gives false positives; if it detects the virus, it basically means the virus is there. But it does give false negatives - some early versions of the test have failed to detect almost 30 percent of infections. That's because the mucus on the swab didn't contain enough virus to show up on the test. That can happen if the swabbing was done incorrectly, or if the amount of virus in the body - the "viral load" - was low. Viral load decreases in later stages of infection, making it harder to detect. It also varies across people in ways we do not fully understand. Some people have a higher viral load than others, and this may cause them to spread the virus more.

What's the other kind of test?
The other type of test you might have is an antibody test, which looks for evidence of past infection. In these tests, we do not see many false negatives. In nearly all cases where there is no antibody detected, the person does not have antibodies. However, these tests do see a lot of false positives. There are many people who test positive for COVID-19 antibodies but do not have them - usually because the test picked up evidence of antibodies to related viruses. An early evaluation suggested that many of the simple finger-prick antibody tests had false-positive rates in the range of 5 to 10 percent.

You probably don't need to sit in a doctor's office to get a test. Most states now have drive-up or walk-up testing sites, where your exposure to other people is minimal. And if you need to go to the doctor for other reasons, you should do it. If you wear a mask and wash your hands, the risk of COVID-19 is probably lower than the risk of failing to address other medical concerns.

The testing looks kind of painful. What does it feel like?Depends on the test you get. The first-line testing for COVID-19 has been using a nasopharyngeal swab, or NP swab, which goes all the way up your nose or down your throat. I'm not going to lie: It can be extremely uncomfortable. In the throat, it feels like you're being gagged. Some people vomit. In the nose, people describe it as tickling your brain. It's over quickly, though, and in the hand of an experienced person it is usually not that bad.

The good news is that testing has moved to two other swab options, called "mid-turbinate" or "anterior nares." Both of these options involve swabbing the nose, but neither test is painful. And recent data suggests that these swabs are just as accurate as the more uncomfortable ones. We're also moving toward testing that will rely on spit, which will eliminate the need for swabbing at all.

The spit test sounds great. What's the hold up? The spit test does sound great. But it's not as accurate as a nose swab - at least not yet. The data suggests it misses around 10 percent of cases, which would be detected with a nasal swab. So as a diagnostic tool, if you're feeling sick, it's not so good.

However, there's a stronger argument for using saliva to get a general sense of population spread. Accurate testing is great, but only if people do it. And - surprise, surprise - people would rather spit than get a swab jammed up their nose. Australia, for example, is using saliva tests because people refused to be tested with a nasal swab. UC Berkeley is giving it a try, too.

Developing a new vaccine would typically take years or even decades. The COVID-19 vaccine pipeline is much, much faster. This is due partly to the number of teams working on it, partly to relaxed restrictions on moving between stages of vaccine development, and partly to the promise of new vaccine technologies.

Vaccines have traditionally worked by introducing weakened or dead viruses into the body, which stimulate the body to preemptively produce antibodies. That's an effective approach, but a slow one to develop, since there are a lot of safety concerns. (You really need to make sure the virus is dead.) More recently, new vaccine approaches have relied on introducing only a portion of the virus, called an antigen. That still prompts the body to make antibodies, without introducing the entire virus.

Now, in the most novel approach, scientists are working to get your own cells to produce the antigen; your body, in turn, produces the antibody. This is cool! Vaccines made like this are potentially very fast to produce. But the approach is largely untested. There may be side effects we do not anticipate, and we don't know if it will even work.

At the moment teams are working on all these approaches, and several are already in the process of testing for safety and efficacy. It's possible that trials will be finished by the end of the summer. But even if the earliest candidates are successful, it will still take a lot of time to manufacture doses.

Early 2021 is probably an optimistic forecast for the first actual vaccines being administered to the population - presumably starting with the highest risk groups. And if the early vaccine candidates fail, it could take much longer than that.

So once we do have a vaccine, how many people will need to get the vaccine for it to be effective? It depends on how effective the vaccine is. If the vaccine promotes immunity in only 60 percent of people, then you'd need every person on the planet to be vaccinated to get to 60 percent immunity. That's the number most often bandied about when we talk about achieving "herd immunity," but it's not supported by very precise data. The best we can probably say at this point is the more people who get vaccinated, the better.

Is the second wave we're hearing about going to be as bad as the first?Honestly, we don't know if there will be a "second wave." This idea seems to be informed, in part, by the experience of the 1918 flu, which saw a wave in the spring and then again in the fall. But we don't yet know enough about COVID-19 to know if it will follow this pattern. What is likely is that as more places reopen, more people will get sick. The best-case scenario is that we use what we've learned from our initial experience to limit the spread. If people keep wearing masks, washing their hands, and maintaining social distance, then there is at least a good chance that any second round of infection will be less bad than the first.

But are hospitals really more prepared now? It seems like they still don't know how to treat this.Yes, they are better prepared. First, they have freed up a lot of capacity. Second, they're getting better at treating the virus, thanks to a combination of experience and new treatments. Hospitals in England, for instance, have seen declining death rates, which may be attributed to the sharp learning curve.

Do they know yet if kids can pass it on to others even if they aren't experiencing any symptoms themselves? Seems like that would have huge implications for schools reopening.The question of child transmission is complicated. There have been strong claims on both sides - that kids don't transmit at all, or that they transmit just as much as adults. In practice, children do seem to transmit the virus less than adults do. In one case, an infected child went to several skiing schools and was exposed to hundreds of people without infecting anyone. And data from the Netherlands suggest that children are relatively unlikely to be the "index case" in their families - that is, they are unlikely to be the first case in a family cluster. But even if kids didn't transmit at all, we'd still want to be thoughtful about reopening schools, since adults can transmit to each other.

In seriousness, most "food shortages" in America were either self-created (panic-buying meat) or reflected a short-run issue in the supply chain (flour). No place in the U.S. really ran out of food.

The big issues we've encountered with supplies are protective gear and tests. But you should not stock up on those, since individual stockpiling leaves less for hospitals and other frontline providers who need them most.

Speaking of protective gear, how effective are masks, really? What are the numbers?A recent meta-analysis in The Lancet suggested that wearing a mask reduces the risk of infection by about 85 percent. But the study was based on observational data, not a randomized trial.

There are some more basic concerns for kids learning to talk, or those with developmental or other issues that mean they need to see mouths move. Face shields, or see-through masks, could provide a solution. I'm guessing this is an area where we'll see substantial innovation.

For starters, it would help if the public-health messaging on masks were more consistent. It is problematic, to say the least, that some leaders are saying it's important and some are not. It also might help to emphasize the personal protections that masks afford. Self-interest is generally a better motivator than appeals to altruism.

Above all, we might make more progress if we make the ask less extreme. When we tell people "wear a mask all the time," they may decide it's just not feasible. I have seen advice urging people to wear a mask during sex. I'm not making that up. It isn't hard to imagine someone seeing that and deciding that the whole enterprise is insane. If we focus on the most important message - wear a mask in stores or public transit - we might get better compliance.

So I don't need to wear a mask during sex?The NYC Department of Health has put out some helpful guidance on sex with masks. The best option, it notes, is to have a stable partner with whom you are comfortable not masking. Unless masks are your thing.

People will disagree, but I think it is unrealistic to expect a serious lockdown to continue through next year. Many people will simply stop listening and do whatever they want. We're going to need to find something that is sustainable. Santa Clara County, for example, is moving to a "risk reduction" order rather than a blanket stay-at-home order. The idea is to recognize that we need to close high-risk environments, but allow people some freedom.

The reality is that any efforts we take to prevent spread are helpful. Wearing a mask when you go out, and washing your hands when you get home, does make a difference. Yes, it's not perfect. Yes, you are more likely to get sick than if you stay home. But every time we prevent the virus from spreading, it grows more slowly or diminishes. That is what we need to keep in mind.

How to convey this to people, I'm not sure about. I think it's about consistency in messaging, and being clear about what actions help most. But it's also about being clear that these actions are not perfect. I worry that someone who gets sick even though they wore a mask all the time will conclude that masks are a hoax. They aren't! They just aren't perfect.

There is so much conflicting information out there, and it's changing all the time, that it's hard to know who to trust. What institutions should I turn to for the most up-to-date information?
For data, I would go to Johns Hopkins and the New York Times. The latter, in particular, has a bunch of nice stuff, including a vaccine tracker. And my own effort, COVID-Explained, offers a wealth of general virus info.

But when it comes to official guidance, I'm at a loss. The CDC has made some significant errors, and the WHO has also been a bit slow on this. We need leadership, but there isn't a clear leader at the moment. That's why America isn't faring as well as some other countries. We've come to distrust government, which is the only institution with the resources and power to protect us in a pandemic.

*A version of this article appears in the July 20, 2020, issue of New York Magazine. Subscribe Now!