COVID-19 has a knack for rebounding just as life starts to reopen a bit more in New York City.

This fall, many businesses began hybrid operations — with a mix of office time and work-from-home schedules. International travelers are flooding back into the boroughs — a potential boon for the hard-hit hospitality industry. And holiday travel has almost rebounded to pre-pandemic levels.

But a coronavirus surge has also snuck up on New York City like a panther. The daily case rate is averaging around 1,300 infections and looks on course to end November twice as high as where it began. That would put infections near this summer’s high mark — when the delta variant took over.

Hospitalizations remain low in the city for now, but these severe cases are rising swiftly upstate. Those places are also less vaccinated than New York City, but one in four people still haven’t taken their shots in the five boroughs. That said, most holiday revelers are currently in a safer position now relative to a year ago when vaccines weren’t available.

But for any concerned parties, COVID-19 safety is all about layering on different types of protection. Vaccines drop risk the most. Testing can help screen out possible carriers. When that fails, mask-wearing indoors and good ventilation can reduce airborne spread.

To gauge how many precautions to take, the first step is thinking about how many people at your gathering would struggle the most if they caught the coronavirus. Next, a party host will want to consider how to limit those risks through a mixture of testing, mask use and ventilation.

No plan will be foolproof, and all gatherings will come with a certain amount of COVID risk whenever case rates rise. As of Tuesday, every county except one in New York, New Jersey and Connecticut is reporting a high level of community transmission. Keeping a few tips in mind can help minimize the danger.

The journey back to normal is naturally going to come with more risks than just staying home. From a public health perspective, people will hopefully try to do the right thing to limit coronavirus spread, while also striking a balance with the decisions that feel right for them.

The Unvaccinated

Start by figuring out how many people are unvaccinated. Real-world estimates, collected this fall by the Centers for Disease Control and Prevention, showed unvaccinated persons to be nearly six times as likely to catch the virus and 14 times as likely to die from it. This trend held steady across all age groups eligible for the vaccines at the time, which means everyone older than 12. All of the country’s authorized and approved vaccines — Pfizer, Moderna and Johnson and Johnson — show this effect.

This year in New York City, the unvaccinated have experienced a rate of 266 cases per 100,000 people. Compare that against 40 cases per every 100,000 who are fully vaccinated. Look at hospitalizations, and it’s 21 for every 100,000 unvaccinated versus 2 among the same amount of inoculated people.

People who recovered naturally from an infection but haven’t been vaccinated should also think of themselves as carrying a greater risk for a bad outcome. Some debate exists over whether this so-called “natural immunity” offers the same protection against a future infection as vaccination, but differences start to emerge when you consider when a recovered person first caught the virus. If you became sick during the first or second waves in 2020, you’re now less protected against the delta variant that rose to prominence this year, according to multiple studies. And when it comes to hospitalization, Americans relying on natural immunity were five times as likely to experience a COVID hospitalization relative to vaccinated people.

The COVID-19 vaccines are also the easiest and most effective way to prevent transmission of the coronavirus. Before the delta variant arrived, inoculation reduced the chances of catching the virus by 90%. Even with the variant, the vaccines still reduce the chances of infection by 67%. Get a booster shot, and the odds return to the 90% range.

Fully vaccinated people are also less likely to spread the coronavirus in the rare cases where they experience a breakthrough infection. A recent U.S. study showed the noses of unvaccinated people excreted the virus for up to nine total days, while for fully vaccinated people, it was only four days. And infections are currently rising fastest among unvaccinated New Yorkers — with case rates about ten times higher among those without shots.

If your gathering intends to mix a lot of unvaccinated people with a bunch of high-risk folks, then you might want to reconsider.

The Vulnerable

Next, you will want to think about how many people would be considered high-risk for severe COVID-19, regardless of their vaccination status.

Even if you factor in the waning immunity, which slowly happens over months, the vaccines still reduce the chances of hospitalization by around 90% or more.

List of studies showing the effectiveness of the Pfizer-BioNTech vaccine by time since second dose.

List of studies showing the effectiveness of the Pfizer-BioNTech vaccine by time since second dose.

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List of studies showing the effectiveness of the Pfizer-BioNTech vaccine by time since second dose.
CDC

But look deeper, and one will find the waning effect is most prominent and most dangerous for vulnerable people. COVID hospitalization is most common among senior citizens, followed by those in their 50s, then those in their 40s and so on. Other at-risk groups include immunocompromised people and those with certain underlying conditions. (The city’s department of health has a nice review sheet at the bottom of this webpage.)

“These are the people who are most likely to have a severe complication from COVID, even if they're vaccinated,” Dr. Céline Gounder, an infectious disease specialist and epidemiologist at New York University and Bellevue Hospital, told Science Friday last week. “They are at higher risk for a breakthrough infection that can progress on to severe COVID.”

It’s obviously too late to get your first course of vaccines or be boosted in time for Thanksgiving. At the quickest, it takes 21 days to receive two shots of Pfizer or Moderna vaccines, then your immune system needs to incubate for two weeks to be fully vaccinated. Children ages 5-11 will still be in this limbo when the turkey arrives, given eligibility for the Pfizer vaccine didn’t open for them until November 2nd. And booster shots, likewise, need 14 days to take full effect.

Testing

So if you’re worried about a contagious person showing up for dinner, then your guests will want to take a COVID-19 antigen test the day before and the day of your gathering.

“The day that a person is contagious, that day those antigen tests are positive,” Dr. Daniel Griffin, an infectious disease specialist at Columbia University, told The Brian Lehrer Show on Friday.

An antigen test detects protein pieces of the virus being pumped out by a well-embedded infection in your nose and throat. Griffin said these antigen tests are very accurate during the period of time when a person is able to spread the virus to others. So that’s either two days before symptoms like runny nose and sore throat appear through about seven to 10 days afterward, when you are still not fully recovered, he said.

“That's when those antigen tests are 98% or, or better at picking it up,” Griffin added.

Or if you’re trying to exclude anyone carrying the coronavirus from entering your gathering, you can go with the more classic PCR test. Because it detects genetic material, a PCR test can detect lower traces of the virus and is 30 to 40% more sensitive than an antigen test. This extra sensitivity means PCR tests are better at identifying people who are not yet contagious -- but also the remnants of an infection in a fully recovered person.

"You may still pick up that infection from four weeks ago with that PCR because they're just so darn sensitive," Griffin said.

Both antigen and PCR tests can be done in 15 to 45 minutes, depending on which clinic you visit or which at-home test you take. But PCR tests, in general, tend to take longer to yield results. In September, health reporter Caroline Lewis wrote a helpful guide for finding all these tests in New York City and what you might pay. Note: Watch out for hidden fees at some for-profit clinics.

Masks

When discussing children, health experts, including New York City Health Commissioner Dr. Dave Chokshi, often say the best mask is the one they can wear consistently and comfortably.

In truth, this rule applies to all ages because masks stymie airborne transmission from anyone who might be positive. During the holidays, this exposure will be the riskiest among crowded places with strangers — such as airports — where you cannot adequately practice social distancing.

So, when picking a mask, focus on two things: the filtration and the fit.

Loosely-fitting cloth and surgical masks will only knock out about 50% of airborne particles, according to multiple studies. But tighten the ear loops on a surgical mask or layer one under a cloth mask, and the filtration jumps up to 70-90%

As their names suggest, N95 masks and their KN95 equivalents from China block 95% of the smallest airborne particles — but again, that only applies if they fit well. People should also watch out for fakes. The CDC says 60% of KN95 masks are counterfeit in the U.S., and it offers a guide for finding legit makers.