The CDC Pivoted On The Delta Variant. Regular Life Can Still Continue.

The vaccines will keep you from dying. Masks will keep away infections. Otherwise, the COVID odds are against you.

These three truths became self-evident after the coronavirus surprised Cape Cod earlier this summer. Starting around Independence Day, a series of indoor and outdoor festivities in Barnstable County, Massachusetts fueled a rapid surge in cases, according to a study published Friday by state health officials and the Centers for Disease Control and Prevention.

The area went from reporting zero cases to 177 infections per 100,000 residents over two weeks—an eye-catching uptick given Bay Staters had among the highest vaccination rates in the country. More than 69% were covered at the time. And of the 469 cases tied to the outbreak, nearly three-quarters—346 people—happened to be fully vaccinated. Experts say that’s well within what’s expected for breakthrough infections—rare instances where the germ circumvents our vaccine-boosted immunity.

But the pivotal moment came when the researchers examined everyone’s nasal swabs. The delta variant accounted for nearly nine of every 10 cases analyzed, and the team discovered that the viral loads were identical between vaccinated and unvaccinated people.

“That is a huge piece of information,” said Dr. Denis Nash, a professor of epidemiology at the CUNY Graduate School of Public Health. “It has major implications for the spread and what we do to control the spread of this virus.”

It means that fully vaccinated people can catch the coronavirus and potentially transmit it as easily as unvaccinated people.

The first part we knew. Breakthrough infections have occurred ever since the clinical trials for the Pfizer, Moderna and Johnson & Johnson shots, but they’ve been rare. Later studies showed all three vaccines reduced the odds of catching the virus—not just severe disease—by about 80 to 99%, depending on the shot.

The second part is a game-changer, said Nash, because the delta variant can infect vaccinated people more often than expected, and those people are now clearly serving as consistent carriers of the virus.

The implications stretch well beyond the scenic beaches of Cape Cod, but they need not derail the voyage back to doing things you love. Schools can reopen. Indoor dining can continue. Outdoor musicians can perform.

But to keep hospitalization surges and mass death from leading to future lockdowns, scientists say society will need to reinstate some simple measures alongside the vaccines.

Do The COVID Vaccines Still Work?

Yes. So far, only four fully vaccinated people have been hospitalized in the Barnstable outbreak, despite hundreds infected. The shots still stopped severe COVID.

But the saga formed the centerpiece of an internal document that inspired the federal pivot on masking this week, as outlined in a CDC presentation revealed by The Washington Post and The New York Times

“High viral loads suggest an increased risk of transmission and raised concern that, unlike with other variants, vaccinated people infected with Delta can transmit the virus,” CDC director Rochelle Walensky said Friday, confirming the news reports. “The masking recommendation was updated to ensure the vaccinated public would not unknowingly transmit virus to others, including their unvaccinated or immunocompromised loved ones.”

The difference between severe disease and breakthrough infections reinforces an important lesson: Vaccine efficacy depends on what outcome you’re thinking about.

Recent delta data from the U.K., Canada and Israel shows that taking the Pfizer vaccine still lowers a person’s odds of hospitalization or death by more than 90%—as long as they’re not immunocompromised.



CDC's internal assessment delta, the vaccines and immunocompromised patients
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CDC’s internal assessment delta, the vaccines and immunocompromised patients CDC

But the protection has lowered when it comes to shielding against initial infection. The vaccine efficacy has now fallen to 60-80% in those instances. Another worrying sign is that the breakthrough rate is 5-7 times higher among Israelis who received their shots in January versus more recent takers, regardless of their age.

While Pfizer and Israel take these trends as signs of immunity waning and motivation for booster shots, the shift could also be due to people mingling more often and boosting their exposure to the virus. The U.S. pulled back from social distancing and masking just as delta arose.

“We’re in a situation where people may not be practicing any of those precautions,” said Dr. Bruce Y. Lee, a public health policy professor at CUNY and executive director of Public Health Informatics, Computational, and Operations Research (PHICOR). “We have to remember that vaccine effectiveness depends not only on your immune response, but it also depends on the situation, the circumstances.”

So Who Is Most At Risk?

The unvaccinated, especially if they’re old or young. These consequences are overwhelming hospitals in the South, and they’re starting to resurface a tragic pattern in New York.

City health officials say the majority of recent hospitalizations involved people without their shots. Their data show that people older than 75 account for more than 100 severe cases, rivaling young adults. But millennials are testing positive at twice the rate of this elderly population.

“This is the nightmare scenario that many of us have worried about,” Nash said, “where now we have a highly efficiently transmitted virus and low vaccination coverage in elderly people.”

Part of this trend is driven by low vaccination rates among the most senior New Yorkers. Only 62% of city residents over the age of 75 are fully vaccinated as of this week. Nationwide, that rate is 77% and overseas in the U.K., it’s 93%.

This COVID cycle keeps repeating itself: Young people might spark an outbreak but it ends with the old and vulnerable. Or to paraphrase culture reporter Van Lathan: The party you have on a Monday night could kill someone else’s grandfather on a Thursday morning.

If Delta Spreads Like Chickenpox, Do We Need To Mask Outdoors?

The CDC’s internal document suggests the average person infected with delta could spread the virus to 8 or 9 others. This pace—or reproduction number—would rival that of he chickenpox or mumps, some of the most contagious viruses on record.

But in reality, the reproduction number can vary slightly depending on how a pathogen moves through a community. The CDC’s estimate is higher than what’s been observed in the U.K., which reported a reproduction number in the range of 5 to 7.

“These estimates can be specific to the conditions of a given outbreak, Nash said, but regardless, “we have a much more infectious virus circulating now than we did several months ago. There are surges in cases even in areas where vaccination rates are relatively high.”

Based on this development, some researchers who helped determine that airborne coronavirus spreads mostly indoors are now saying that delta raises the risk outdoors, specifically for people standing or sitting still in crowds.

While this might feel like a reversal, Lee from CUNY says this was always the case.

“You don’t have one set of rules for indoors and something completely different outdoors. It’s actually a continuum,” he said. “Outdoors helps because there’s the wind outside, and it’s easier to space yourself. But if you’re still in a situation where people are in close quarters, and there’s not as much immediate circulation of the air right around you, it’s potentially a risky situation.”

But the opposite is true, too. If you’re in a place with good air circulation—like a baseball game—then the threat drops. Space out the seats or install ventilation like fans, the danger erodes even more. Layer masks or vaccination on top of those measures, and the risk pushes toward zero.

Will NYC Return To Universal Indoor Masking?

During a Friday appearance on CNN, New York City Mayor Bill de Blasio was asked why he was electing to wait on reinstating a mask mandate.

“It’s important not to lose the forest from the trees…The main event is vaccination,” de Blasio said. A day earlier, he hinted further guidelines on face coverings might arrive as early as Monday. But masks, he added on CNN, “don’t change the reality. Vaccination does.”

Vaccine coverage, meanwhile, is slowly rising after stalling citywide at 50-60%, depending on the borough. The city has thus far gone with a mix of mandates and incentives to jumpstart its progress. On Wednesday, the mayor announced that the city would give $100 to people who received their first shots at a city-run vaccination site. The city is also requiring that people be vaccinated if they attend one of its highly publicized “Homecoming Week” concerts. And beginning in mid-September, all of the city’s 340,000 municipal employees must either be vaccinated or get tested weekly.

But de Blasio told CNN that he would not cancel the concerts in light of the growing concern about the delta variant.

Elected officials, however, have argued that the city should be willing to adopt a multi-pronged strategy, especially since masks are a validated form of protection against the coronavirus.

“We’re letting the virus outrun us again. Stunning,” tweeted Mark Levine, a Manhattan City Councilmember who chairs the Council’s health committee. Asked about Levine’s comments, de Blasio replied, “We’re acting fast on the things that make a difference.”

Given the Barnstable outbreak and other recent trends with delta, many health experts side with Levine. Indeed, every single scientist interviewed for this story said that city, state and federal officials lifted indoor masking prematurely this summer.

Recent data from the U.K. shows reinfections among recovered patients are 46% more common with the delta variant.

All of the earlier assessments of the vaccine were just that—early. Researchers and health regulators measured vaccine effectiveness against coronavirus transmission shortly after shots were given.

“Circulating antibodies in your body immediately following vaccination are high and will be more effective at protecting you from being infected,” said Dr. Theodora Hatziioannou, a virologist at Rockefeller University in New York City. “But they wane over time, so they will likely become less effective from curtailing transmission a few months later.”

So far, vaccination will still allow our immune system to protect us from severe disease after infection. Some antibodies remain potent, and our T-cells—the wardens of immunity—can still clear out the virus. But Hatziioannou says those initial measurements made people overconfident.

We’ve since learned that only full vaccination—one shot of Johnson & Johnson or two doses of Pfizer/Moderna—can shield against severe disease and death caused by the delta variant. Masks can prevent the spread.

Alternatives, such as natural immunity after recovering from an infection, won’t be enough. Recent data from the U.K. shows reinfections among recovered patients are 46% more common with the delta variant.

Broadway and other businesses are aware of these realities and instituting vaccine mandates after the U.S. Justice Department deemed it legal last week—as cases double in New York City every two weeks.

“We’re headed into a crisis in New York, with regard to increased transmission, and many places around the country are already having serious outbreaks,” Nash from CUNY said. “It’s time to really change our mindset in New York City and begin to think about masks again.”

Elizabeth Kim contributed to reporting.

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