It is the most important issue in New York City right now, a critical threshold that triggers restrictions from state and local authorities in response to coronavirus. The mayor of New York closed public schools by 3 percent. The governor says a sustained level of 3 percent in the city would result in banning indoor dining, closing gyms and hair salons and placing a 25-person hood to attend prayer houses, even as the holiday season approaches.
But as important as the number is, it seems that the city and the state cannot agree on whether we are there yet.
The discrepancy may be striking: Sunday, for example, the city said its seven-day average was 3.09 percent. Sir. However, Cuomo’s office put the city’s rate at more than half a point lower, 2.54 percent.
In a way, of course, not all numbers are the same, as Mr. Cuomo’s statistics from the State Department of Health govern a wider range of activities and businesses in regions throughout New York. But Mr Cuomo granted local school districts the right to set their own parameters for school closures, and Mr De Blasio, who controls the school system, set 3 per cent as this level.
And in the end, it was the city’s numbers that caused the temporary break with personal learning in the country’s largest school system.
Why can they not agree on whether we are 3 percent?
The reason for the discrepancy lies both in the tests included and in the time frame in which statistics are reported, leading to the mayor and governor giving different numbers each day.
It’s the latest inconsistent message between two rivals that has played out across the pandemic, adding a level of dysfunction and confusion to the reaction.
On Sunday, Cuomo suggested that the city’s calculation of its positive rate was “confusing and unnecessary” and also “irrelevant” because state figures would govern any broader constraints.
The state and city health departments actually have several different accounting rules to track the spread of the virus. The state is treating a new case as it arose on the day the test results came in. The city dates each new case to the day the sample was delivered.
So if an infected person goes to a clinic to have his nose dried on Monday, the sample is often delivered to a laboratory where it is tested. If these results are reported to the health authorities on Wednesday, the state and the city would register it differently. The state would include it with Wednesday’s inventory of new cases, while the city added it to Monday’s column.
The 3 percent threshold is based on a seven-day moving average. It matters what day a new case is registered.
Another factor also contributes to the discrepancy that has received little attention so far: antigen experiments. New York State includes the tests in its official measurements. However, while they are generally faster, they are less likely to detect the infection in people with low viral load.
However, New York City does not include antigen experiments, as they prefer a more sensitive one, known as a polymerase chain reaction test. The city only includes PCR tests performed in a laboratory in its census. Therefore, the state – which counts both antigen and PCR tests – may have a higher vote for general cases in New York City, but a lower percentage of positives.
PCR tests in a laboratory have long been considered the gold standard because they are unlikely to miss out on infections. However, some public health experts say that much of the PCR test for coronavirus is too sensitive, resulting in coronavirus diagnoses for people who carry relatively insignificant amounts of the virus and are probably not contagious.
Antigen tests, which can be performed quickly and inexpensively, detect bits of coronavirus proteins. However, they are more likely to miss cases, including people who are recently infected and who have lower viral load.
The difference in sensitivity between the two types of tests has contributed to a growing gap in the positivity rate between the city and the state.
In fact, the degree of positivity for the same group of people – in this case New York City residents – can vary depending on how many receive antigen tests versus traditional PCR tests. Antigen testing can be missed in some cases when the amount of virus is still low.
Say 1,000 people are being tested. Let us assume that everyone has a PCR test and that 30 tests are positive at a positivity rate of 3 percent. Let us assume that half get an antigen test and half get a PCR test. Maybe only 25 tests come back positive for a positivity rate of 2.5 percent.
“We believe in our numbers and our method,” said Bill Neidhardt, the mayor’s spokesman, referring to the mayor’s decision Wednesday to declare the 3 percent threshold reached, rather than adopt the state measure in a last-minute bid to keep the schools. open.
“Changing a public health standard in the middle of the morning is not a good idea for clarity and public confidence,” he said.
Gary Holmes, a spokesman for the state health department, said the state reported on both types of tests “to provide the clearest possible picture of people diagnosed with Covid in a given period of time.” A positive result on either a PCR or an antigen test requires a person to quarantine.
On Sunday, Mr Cuomo said the state conducts “hundreds of thousands of antigen tests a week” and noted frequent trials of nursing home workers, adding that exclusion from them would “reduce the database significantly.” Such quick results may also be in high demand in the coming weeks as people seek tests before the holidays, the governor’s office said. “It’s nice to know that quickly,” Cuomo said.
There are other differences in how the city and the state calculate the degree of positivity that also help explain why the city’s rate is higher.
For example, if a person tests negative repeatedly within a seven-day period, the city only counts a single test when calculating the positivity rate. But the state includes all negative tests from different days in its calculation.
Confused by the terms of the coronavirus test? Let us help:
- Antibody: A protein produced by the immune system that can recognize and bind accurately to specific viruses, bacteria or other invaders.
- Antibody test / serology test: A test that detects antibodies specific for coronavirus. Antibodies begin to appear in the blood about a week after the coronavirus has infected the body. Because antibodies take so long to develop, an antibody test cannot reliably diagnose an ongoing infection. But it can identify people who have been exposed to coronavirus in the past.
- Antigen test: This test detects bits of coronavirus proteins called antigens. Antigen tests are fast and take as little as five minutes, but are less accurate than tests that detect genetic material from the virus.
- Coronavirus: Any virus that belongs to the Orthocoronavirinae family of viruses. Coronavirus that causes Covid-19 is known as SARS-CoV-2.
- Covid19: The disease caused by the new coronavirus. The name is an abbreviation for coronavirus disease 2019.
- Insulation and quarantine: Isolation is the separation of people who know they are sick with a contagious disease from those who are not sick. Quarantine refers to restricting the movement of people who have been exposed to a virus.
- Nasopharyngeal swab: A long, flexible stick with a soft cotton swab that is inserted deep into the nose to get samples from the space where the nasal cavity meets the throat. Samples for coronavirus tests can also be collected with swabs that do not go as deep into the nose – sometimes called nasal swabs – or oral or throat swabs.
- Polymerase Chain Reaction (PCR): Researchers use PCR to make millions of copies of genetic material in a sample. Tests that use PCR allow researchers to detect coronavirus even when it is scarce.
- Virus load: The amount of virus in a person’s body. In people infected with coronavirus, the viral load may peak before they begin to show symptoms, if symptoms appear at all.
On the other hand, when someone tests positive repeatedly, the city includes each positive test in calculating the positivity rate. However, the state only counts the first positive test and ignores the subsequent ones.
The last variable – whether repeated positives are counted or not – can have a great influence on the degree of positivity. Gareth Rhodes, a member of Mr. Cuomos coronavirus taskforce, estimated that approx. 15 or 20 percent of positive PCR tests currently coming from New York City were to someone who had previously tested positive.
Why does it matter?
If New York City hits 3 percent based on state polls, the governor has suggested it will enter a so-called “orange zone,” amid three color-coded restrictions adopted by the governor in early October.
Under the governor’s plan, a so-called “red zone” is subject to the strictest restrictions with a ban on mass gatherings, indoor dining and personal learning. Non-essential businesses would close, and religious services would be limited to 25 percent capacity in houses of worship or 10 people, whichever is lower.
“Orange zones” – which the governor says the city is in danger of falling into – allow for small gatherings and outdoor dining, but schools are closing down, as are “non-essential” shops like hairdressers and gyms. Preventive zones – appropriately yellow – allow for personal classes, but reinforce testing and put some less stringent caps on dining and gatherings.
Four of the city’s five boroughs – Queens, the Bronx, Brooklyn and Staten Island – already have yellow zones, and Mr. Cuomo said Upper Manhattan may have imposed one later this week. The State of Iceland may also be subject to aggravating restrictions.
These zones are re-evaluated after two weeks, and the measurements to get in and out of each of these zones involve a complicated mix of data and a touch of deliberation: Limitations can be changed after “expert advice”, says the state and includes decisions based on local hospitalization rates , or whether outbreaks can be traced to a single source (such as prison, gathering or group stay).
Other factors may include “compliance and enforcement measures taken by local authorities” as well as more vague standards such as “community cooperation to reduce virus spread.”
Which, of course, could make a clean slate – like 3 percent – less important.
Can the city act alone?
Based on its polls, New York City has already reached the 3 percent mark. Still, it can still take a while before companies face any restrictions.
Not only do state statistics put the city’s seven-day rolling average below this figure, but New York City must exceed this threshold for 10 consecutive days before the city should enter the “orange zone.”
Technically, the city could use multiple solutions to target businesses that they decide to contribute to virus spread. For example, the city’s health ministry could try to close any restaurant by declaring it a threat to public health.
But the governor has broad contingency powers over a number of companies and trumps Mr. of Blasio. At news conferences, the mayor sometimes sounds a dissuasive note saying that certain decisions about closures should be left to the governor.
So for now, New Yorkers will continue to wait for the city to hit 3 percent … again.