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A friend invited me to her home for a birthday party. “Ten of us will be there,” she wrote. “I’m pretty sure we’ve all been vaccinated, so we should be OK.”

It was the first invitation to an indoor dinner I had received in almost a year.


Six other friends are planning a tropical vacation and invited me to join them.

“Aren’t you worried about Covid?” I asked, feeling a bit nerdy for raising the question.

“Not really. Two of us have gotten both our vaccines.”


“What about the others?”

“Two have gotten one vaccine each, and the other two have been very careful.”

And this from another friend: “I feel like I just got into Harvard Law School!” she wrote. “I just got my first vaccine! But is it now OK to fly if I wear a mask the whole time?”

These people are struggling with the same questions about safety I’m struggling with, having just been vaccinated. We are wondering how to change our behaviors and interactions, and understand just how protected we and the others we encounter are — or aren’t.

In early March, the Centers for Disease Control and Prevention released guidelines stating that fully vaccinated people can visit each other or members of a single unvaccinated household indoors without wearing masks or physically distancing themselves. These clarifications, along with the fact that millions of Americans are now getting shots, are welcome news.

But how will Americans respond? In the next weeks and months, millions of people will confront myriad nuanced and complex individual choices — which gatherings to attend, with whom, and how certain we need to be that we are indeed safe from spreading or receiving the virus.

The problem is that humans aren’t good at gauging risks.

Maskless young people are now thronging bars. Texas Gov. Greg Abbott decided to fully open his state. As his decision indicates, many people may now also engage in risk compensation, in which they act in riskier ways if they have taken measures that they feel are protective. Seat belt use, for example, has failed to lower fatal car accidents, since drivers wearing seat belts then compensate and drive faster or less carefully. Sunscreen use has increased melanoma rates because users feel they can now expose themselves to more sun.

Vaccines are absolutely essential for stopping Covid-19, but they reduce — not wholly eliminate — the odds of being infected with the virus. The Pfizer and Moderna vaccines are around 95% effective at reducing severe disease, while the Johnson & Johnson vaccine is about 85% effective. Those are high numbers for vaccines, but not guarantees of safety. For every 20 people who receive the Pfizer or Moderna shots, one could still acquire Covid-19 and become seriously ill.

Covid-19 and other viruses also mutate, sometimes rapidly. As billions of cells in millions of humans replicate the virus, its genetic material constantly changes, sometimes in ways that circumvent our defenses and vaccines. At least one vaccine has been found to be significantly less effective against one such mutation. Current vaccines may not end up protecting against all the new variants.

Scientists also aren’t sure how long the vaccines’ protections will last, and whether vaccinated individuals can get infected and spread Covid-19, even if they themselves don’t get sick.

The human brain evolved to face simple risks, like whether a certain plant is safe to eat. But far more complex and nuanced dangers now fill our world. Neurocognitively, we commonly assess risks using so-called fast thinking, which is essentially gut feelings. As the anthropologist Mary Douglas wrote in her classic book, “Purity and Danger,” people tend to divide the world into the two realms of “risky” and “safe” — what is dangerous and to be avoided vs. what isn’t — or essentially bad vs. good. Our brains see these dichotomies in black and white rather than shades of gray. We don’t deal well with ambiguities or notions of relative safety, and like to think of situations as merely either completely safe or unsafe, rather than as partially or relatively safe.

Public health officials have long recognized such complex realities about harm and safety. To address them, they’ve pursued so-called harm reduction strategies. The fight to control HIV is an example. Some people who injected opioids or other drugs into their veins shared needles, spreading HIV and hepatitis, which can lead to disease and death. Over decades, federal and state and local governments spent hundreds of millions of dollars trying to stop addiction, but with limited success. One solution to stop HIV from spreading was by providing clean needles — a harm reduction approach. Although many states have staunchly opposed this tactic, fearing it would fuel addiction, it works in significantly cutting HIV infections and not fostering addiction.

In the months ahead, many people will face complex decisions with no easy answers. Though desires to feel safe against Covid-19 run deep, we need to accept, and adapt to, far more complex realities, like how comfortable we are that everyone at a dinner party has indeed been fully vaccinated and hasn’t then entered a relatively crowded subway, bus, store, bar, or other area without a mask.

The CDC, Food and Drug Administration, and other federal, state, and local public health agencies, along with elected officials, hospitals, physicians, and medical associations, urgently need to work to enhance public understanding of these issues through appropriate public health messaging campaigns. These messages need to convey the complexities of risks: the fact that being vaccinated is not a 100% guarantee of safety.

We each need to remain careful. Research suggests that until the vast majority of people get vaccinated and wear masks and social distance when they should, Covid-19 will remain around us in schools, stores, and elsewhere.

I got more information about the birthday party and learned that all of those attending would be fully vaccinated before the event. So I’m going. I also decided to join the beach trip, but will drive, not fly, and will continue to wear a mask and social distance.

I look forward to more invitations, but I’m not sure how I will respond.

Robert Klitzman is a professor of psychiatry at the Vagelos College of Physicians & Surgeons and the Joseph Mailman School of Public Health, both at Columbia University, director of the university’s online and in-person masters of bioethics programs, and author of “The Ethics Police?: The Struggle to Make Human Research Safe” (Oxford University Press, 2015).

  • “entered a relatively crowded subway, bus, store, bar, or other area without a mask”

    It’s ironic that you’re writing this article while still under the impression that wearing a mask protects the wearer.

  • This statement is simply not true.

    ” The Pfizer and Moderna vaccines are around 95% effective at reducing severe disease, while the Johnson & Johnson vaccine is about 85% effective. Those are high numbers for vaccines, but not guarantees of safety. For every 20 people who receive the Pfizer or Moderna shots, one could still acquire Covid-19 and become seriously ill.”

    This a glaring mathematical error. Think about it, if the 99 percent effective polio vaccine was considered under this logic, there would be 3,331,000 polio cases in the US. There were less than 70 last year. It’s called herd immunity, Doctor.

  • Fascinating article. I enjoyed observing your thought processes. Here in Louisiana, the majority of the population is not nearly as cautious as your circle of friends. Most people (with some exceptions) resumed dinner parties and social gatherings after the lockdown was lifted last May. You go to the Bourbon Street in New Orleans and revelers are partying like there’s no tomorrow, with only a minority covering their faces.

    One interesting issue to ponder is that before the vaccine rollout, the immunity in the population came entirely from natural infection. At the beginning of a Covid-19 wave, the social butterflies were always the first to be infected and spread the illness to their large circles of friends. This would lead to a rapid rise in infections. Soon most of the super spreaders would be immune, however (at least temporarily), and cases would start to decline, even if the fraction of the population that was immune was still relatively low (the variance in the number of people each individual infects, rather than the mean, is the critical factor to consider here). See the Britton et al., 2020 article in Science Magazine for a mathematical analysis (

    With vaccination, however, it appears that the people being vaccinated are the ones who are already cautious and unlikely to become infected and spread the disease. Therefore, it will be harder for vaccination to reduce the effective reproduction number to less than one during future Covid-19 waves (assuming, of course, that vaccination reduces transmission in addition to disease severity).

  • foolish.

    Outside of the two excruciatingly long days I spent getting my shots, {three hours on the bus, an hour standing in line and going through the shot process}, I haven’t been within ten ft of anybody for a year.

    I kinda despise those weak enough to need to be all palsy-walsy irl. Either covid will mutate or anothr virus will slither in. It’s sad kids are growing up socially stunted. I guess that’s better than killing a bunch of teachers.

  • I’m glad to read you’re pondering worthy issues, and sorry to learn you’re making poor decisions.
    EVERYONE should continue to exercise extreme caution so long as COVID is so strongly present in communities.
    You might be correct in gambling that you’ll be ok driving to your “tropical” vacation. But there’s no data that shows vaccinated people can’t carry and transmit COVID to others without becoming ill themselves. You might just become responsible for someone else’s illness.
    Meanwhile, if everyone truly adhered to limitations and restrictions, the virus would have essentially died out long ago (see Australia) or could still much more quickly.

    • First of all EVERYONE will never be able to adhere to all restrictions, so your theory isn’t logical. Next there is evidence of past pandemics that the lockdowns and closures and restrictions had no effect in limiting spread, as well as the data on states that had restrictions and mask mandates vs. those that did not. Note California (strictest) vs. Florida (among least restrictive) have had very similar numbers of cases, etc. Then, the virus is not going to die out, note seasonal flu. We live WITH it and manage without restrictions, and should be doing the same with this virus, since we know it is significant for less that 99% of the population. We are acting like it’s a nuclear explosion when in fact the chances of dying in a car crash are 100 times greater than dying of covid19 and I don’t see anyone changing their driving behavior.

    • Who are you to judge someone else’s decisions as being poor, for that person. Poor for you perhaps. Did you ever stop to think that since it has been over a year since we have known about this virus, and that if you haven’t gotten sick by now you likely not going to? Unless you are elderly and have significant health issues. So why all the gloom and doom? Don’t you want to get back to a somewhat normal life? Don’t you want to look out into a crowd and see lots of happy smiling faces, rather than a spread out sad looking group peering out over a mask? Don’t you want to see people greeting and laugh and shaking hands and hugging, rather than hanging their heads and dragging along like the very effort to exist outside of the house is exhausting? I find it exhausting just watching this scenario every day, and trying to comprehend what masked mouths are mumbling. There is so much more at stake here than the POSSIBILITY of getting the virus even if vaccinated, and your continued worries and defenses of your stance no matter what options are placed before you are evidence of that. It is really time to just decide enough is enough and go out and live. Get the vaccine if you want and then trust that and your own body that has protected you so far to so you can stop hiding and move forward.

    • So, Jody, where is the enormous pile of 50 million American corpses that died in those vastly more dangerous car crashes you’ve warned us about? Are you an intellectual titan who has just uncovered the most successful cover up in history, or a vapid conspiracy theorist grasping at statistical straws in a vain attempt to cling to your prejudices? I know what my money’s on.

  • “Those are high numbers for vaccines, but not guarantees of safety. For every 20 people who receive the Pfizer or Moderna shots, one could still acquire Covid-19 and become seriously ill.”

    You are wrong about what it means to be 95% effective. It does not mean 1 in 20 risk. It is a measure that compares people in placebo group who got sick to the people with vaccines who got sick. Of the 44,000 vaccinated, 170 got covid. 162 placebo to 8 vaccinated. 162/170 is 95%.

    In the study, fewer than 1/10th of 1% of vaccinated caught covid.


    • There are no guarantees of safety. We take chances every day, most of the time without thought. Why is this so much different? It isn’t really, it is just how it has been presented as if it is something more deadly than death itself. People forget that there are things we die of all the time, many more deadly and horrific than this, but we don’t think about that daily like we now do covid. Everything says “beware covid”, so even if we wanted to stop thinking about it (I do!), we couldn’t. We are forced everywhere we go to be reminded that covid is just around the corner and death is surely right behind. I am not denying people have suffered, and have died. But they suffer and die of things every day, all day long and we don’t have that shoved in our face constantly. And of course no vaccine is 100% effective for 100% of those who get it, for any disease. But we just get it and go on about life. This covid is killing more from mental, financial, physical, social, and environmental effects than from actual covid-caused deaths.

  • Every discussion about this takes me back to the variants.
    If we were only dealing with the first type, which at least 1/4 of us are immune to from past infection, and a 95% effective vaccine, and 3/4 of us vaccinated soon, that is a no-brainer – live your life as before, and do not worry.
    The variants may toss out all of the above. We may have a brand new epidemic – or multiple brand new epidemics concurrently.
    My take is, since I am vaccinated against the first strain, I am relaxing and living normally for now – but in my area, the variants have already been detected in people who did not travel. Both South African and Brazilian, more than one case of each – so, I figure a wave of infections from them is coming, and when they get more commonplace, I will start to be a lot more careful.
    I wish articles about this would address the variants more – so far, all I hear is what sounds like wishful thinking, with no clear proof, our vaccines will work.

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