This is the most important number in New York at the moment, a critical threshold that causes restrictions by state and local authorities in response to the coronavirus. The mayor of New York closed public schools at 3 percent. The governor says a sustainable 3 per cent level in the city would lead to a ban on indoor eating, the closure of gyms and hairdressing salons and the putting on of a cap by 25 people to attend prayer houses, even as the holidays approach.
But as important as this number is, it seems the city and the state can’t agree on whether we̵
This is the situation that took place last week, with Mayor Bill de Blasio saying that 3 percent had been reached, while Governor Andrew M. Cuomo said it was well below that. Everyone relies on their own statistics, which are compiled and reported in different ways. And it turns out that the state and the city can not agree on which tests to include in the calculation.
The discrepancy could be staggering: On Saturday, for example, the city said its average for seven days was 3.11%. However, Mr. Cuomo’s office set the city’s percentage more than half a point lower, at 2.54 percent.
In a way, of course, not all numbers are equal, as Mr Cuomo’s statistics from the State Department of Health manage a wider range of activities and businesses in regions of New York. But Mr Cuomo gave local school districts the right to set their own parameters for shutting down schools, and Mr de Blasio, who controls the school system, set 3 per cent at that level.
So, in the end, it was the number of the city that caused the temporary pause of personal education in the largest school system in the country.
Why can’t they agree if we’re at 3 percent?
The reason for the discrepancy lies in both the tests that are included and the time frame in which statistics are reported, which means that the mayor and the governor give different numbers every day.
This is the latest controversial message between two rivals that took place throughout the pandemic, adding a level of dysfunction and confusion to the response.
State and city health departments have different accounting rules to track the spread of the virus. The state treats a new case as having occurred on the day the test results entered. The city dates each new case on the day the sample is provided.
So, if an infected person goes to a clinic to have their nose taken on a Monday, this sample is often delivered to a laboratory where it is tested. If these results are reported to health authorities on Wednesday, the state and the city will record it differently. The state will include him in the new cases listed on Wednesday, while the city will add him to the column on Monday.
The 3 percent threshold is based on a seven-day moving average. It is important on which day a new case is registered.
Another factor contributes to the discrepancy, to which little attention has been paid so far: antigen tests. The state of New York includes the tests in its official indicators. But while they are usually faster, they are less likely to detect the infection in people with a low viral load.
However, New York does not include antigenic tests, preferring a more sensitive one, known as a polymerase chain reaction test. The city includes only laboratory PCR tests. Therefore, the state – which reports both antigen and PCR tests – may have a higher sum for the general cases in New York, but a lower percentage of positive results.
Laboratory PCR tests have long been considered the gold standard, as they are very unlikely to miss any infections. But some public health experts say much of the PCR tests for coronavirus are too sensitive, leading to diagnoses of coronavirus for people who carry relatively small amounts of the virus and are unlikely to be contagious.
Antigen tests, which can be performed quickly and cheaply, detect bits of coronavirus proteins. But they are more likely to miss cases, including recently infected people who have a lower viral load.
The difference in sensitivity between the two types of tests contributed to increasing the difference in the degree of positivity between the city and the state.
In fact, the degree of positivity of the same group of people – in this case New Yorkers – may vary depending on how many people receive antigen tests compared to traditional PCR tests. Antigen tests may miss some cases where the amount of virus is still low.
Let’s say 1,000 people are tested. Let’s assume that everyone has a PCR test and that 30 tests are positive, for a degree of positivity of 3%. Now let’s assume that half get an antigen test and half get a PCR test. Maybe only 25 tests return positive, for a degree of positivity of 2.5 percent.
Bill Neidhard, a spokesman for the mayor, noted that the city’s decision to exclude antigen tests from positivity reflects the CDC protocol.
“We believe in our number and our methodology,” he said, before hinting at the mayor’s decision Wednesday to declare the 3 per cent threshold violated, instead of adopting the state-run indicator at the last minute to keep schools open.
“Switching to the public health standard in the middle of the morning is not a good idea for clarity and public trust,” he said.
Are you confused by the test conditions for coronavirus? Let’s help:
- Antibodies: A protein produced by the immune system that can recognize and attach precisely to specific types of viruses, bacteria or other invaders.
- Antibody test / serological test: A test that detects coronavirus-specific antibodies. Antibodies begin to appear in the blood about a week after the body is infected with the coronavirus. Because antibodies take so long to develop, the antibody test cannot reliably diagnose a continuing infection. But it can identify people who have been exposed to the coronavirus in the past.
- Antigen test: This test detects bits of coronavirus proteins called antigens. Antigen tests are fast, taking only five minutes, but are less accurate than tests that detect genetic material from the virus.
- Coronavirus: Any virus that belongs to the family of viruses Orthocoronavirinae. The coronavirus that causes Covid-19 is known as SARS-CoV-2.
- Covid19: The disease caused by the new coronavirus. The name is abbreviated from coronavirus disease 2019.
- Isolation and quarantine: Isolation is the separation of people who know they have a contagious disease from those who are not. Quarantine refers to restricting the movement of people who have been exposed to a virus.
- Nasopharyngeal tampon: A long, flexible stick tilted with a soft swab that is inserted deep into the nose to take 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 a lip or throat swab.
- Polymerase chain reaction (PCR): Scientists use PCR to make millions of copies of genetic material in a sample. Tests that use PCR allow researchers to detect the coronavirus, even when it is scarce.
- Viral load: The amount of virus in a person’s body. In people infected with the coronavirus, the viral load may peak before they begin to show symptoms, if symptoms at all.
Gary Holmes, a spokesman for the US Department of Health, said the state was reporting both types of tests “to provide the clearest possible picture of people diagnosed with Covid over a period of time.” He added that although there are differences between PCR and antigen tests, the state “has issued extensive guidelines on how the results of antigen tests should be interpreted, including when the need for confirmatory testing is recommended or required.”
Why does it matter?
If New York reaches 3 percent based on state indicators, the governor assumes that he will enter the so-called “orange zone”, the middle of three color-coded restrictions that the governor introduced in early October.
According to the governor’s plan, the so-called “red zone” is subject to the strictest restrictions, with bans on mass gatherings, indoor dinners and personal training. Minor businesses will close, and religious services will be limited to 25 percent of the capacity of prayer houses or 10 people, whichever is smaller. These areas were used for heavy fires in Brooklyn in October, leading to protests in some Orthodox Jewish communities, where the virus is spreading rapidly.
The “orange zones” – in which the governor says the city is in danger – allow for small gatherings and open-air dinners, but schools stop, as do “risky” non-essential companies such as barbershops and gyms. The safety zones – suitably yellow – allow personal classes, but increase the tests and put less strict caps on the table and gatherings.
These areas are re-evaluated after two weeks, and the entry and exit indicators from each of these areas include a complex combination of data and a dash: The restrictions can be modified to “expert consultation,” the state said, and include definitions based on local levels of hospitalization or whether outbreaks can be traced to a single source (such as prison, assembly, or group residence).
Other factors may include “compliance and enforcement actions by local authorities”, as well as less clear standards such as “community cooperation to reduce the spread of viruses”.
Which, of course, can make a simple number – say 3 percent – less important.
Can the city act alone?
Based on its indicators, New York has already reached the limit of 3 percent. Still, it may be some time before the business faces any restrictions.
State statistics not only put the city’s seven-day moving average below that number, but New York must break that threshold for 10 consecutive days before the city enters the “orange zone.”
Technically, the city can use several workarounds to target the business it decides contributes to the spread of viruses. For example, the city’s Ministry of Health may try to close any restaurant by declaring it a threat to public health.
But the governor has broad emergency powers over a number of businesses, overpowering Mr de Blasio. At press conferences, the mayor sometimes voices a resigned note, saying that certain closure decisions should be left to the governor.
So for now, New Yorkers will continue to wait for the city to reach 3 percent … again.