Covid-19 data remain mixed in inconsistencies

The testing was uneven between states and communities. The number of cases, the lack of asymptomatic and mild infections, is too low. And death efforts are considered incomplete.

According to some estimates, for every case documented by Covid-19, there are at least two undetected infections, and the unusually high number of deaths that occurred last year suggests that the virus could have killed more people than the data recorded.

By the end of 2020, nearly 346,000 deaths in the United States had been attributed to Covid-19, according to Johns Hopkins University, but the Centers for Disease Control and Prevention estimates that 450,000 excess deaths occurred that year.

“That’s 450,000 more than we would have in a normal year,” said Robert N. Anderson, head of mortality statistics at the CDC’s National Center for Health Statistics, which uses death certificates to track how many people there are. dies annually. “We already know that we had over 300,000 deaths due to Covid-19. Of the other group, probably 100,000 can be attributed to the pandemic, but not necessarily to the virus. ”

Currently, the best data available to the public are hospitalizations.

“We see it as one of the main highlights of Covid’s entire response,” said Alexis Madrigal, co-founder of the Covid Tracking Project, a volunteer organization that collects and publishes pandemic data. “It’s the best and most detailed data set we have.”

Initially, the Department of Health and Human Services published only state-level information, but since December, the data has provided hospital capacity and bed use for each unit, exposing which ones are overloaded.

“In the beginning, if it had been available, it could have stopped misinformation by showing how widespread it was and supporting the incredibly emotional testimony of health care workers about what was happening in hospitals,” Mr Madrigal said.

In real time, testing, the number of cases, hospitalizations and death measures help health workers and decision-makers to monitor the disease, develop strategies to reduce its spread and to allocate sometimes scarce resources.

In retrospect, the analysis of data sets – even if they are imperfect – can help assess the effectiveness of decisions made and improve future responses.

“Much of the reason we fought in the United States is that we have such a vague approach to healthcare,” said Beth Blauer, executive director of the Johns Hopkins University Center for Civic Impact. “It has led states to implement things quite differently and made it very difficult to create a comparison between apples and apples.”

The first hurdle was testing.

Initially, the tests used to identify Covid-19 were severely limited. When they became more accessible, they were administered inconsistently and reported differently between jurisdictions.

Some sites counted only antibody tests performed by laboratories, while others also counted less sensitive antigen tests performed outside laboratories.

States then used different methods to calculate positivity rates – and because some people were tested several times, they raised questions about whether the rates should be based on the number of tests administered or the number of people tested.

“We thought it was very important to understand how many people were tested and what the yields were,” said Dr. Blauer. “It wasn’t that simple.”

The way states calculate positivity rates is still a bag, she said, but test data could still be valuable for long-term research.

“When we compare the number between states and counties, we can ask ourselves why one place was spared and another not?” said Jennifer Nuzzo, associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health. “Was it really spared or just wasn’t tested?”

Standardization is also an issue with the number of cases.

According to the Council of State and Territorial Epidemiologists, standardized surveillance is needed to ensure consistent identification and classification of cases, to measure the potential burden of the disease, and to inform the public health response.

But some states report only confirmed cases, while others also report probable cases – a definition that has changed over time.

Even with perfect reporting, the number of cases does not capture the total number of infections. Missing are people who are asymptomatic or who have been only slightly ill and have never been tested.

However, the number – perhaps increased by further research – will help epidemiologists estimate the number of infections. And the causes of death listed on the death certificates will help them deduce how many people actually died from the disease.

“We would find out if this is a cause of death that is associated with Covid and if we can safely say that these are probably Covid deaths,” said Dr. Anderson. “It simply came to our notice then. If we get the excess deaths from pneumonia in the Covid pandemic, we know that Covid frequently causes pneumonia. ”

It is more complicated to look at, say, heart disease.

“We know that Covid can cause a heart attack or stroke,” said Dr. Anderson. But it is also possible that some are just heart disease or stroke deaths. It will be very difficult to sort there. We would probably make models based on different hypotheses. ”

The CDC will not change the underlying records, but states have the option to change death certificates, and a hand has been changed to reflect deaths caused by Covid-19 that occurred before the first U.S. case was diagnosed on January 20, 2020.

Two were on January 4, 2020 and three were on January 18, 2020.

“We’ll never have a perfectly accurate number, but we can get an idea of ​​how accurate it is likely to be,” said Dr. Anderson.

Data collected by groups, including the CDC, HHS, Johns Hopkins and the Covid Tracking Project, is available to the public, and President Biden is now committed to creating a nationwide pandemic dashboard with ZIP code data.

All the information will be used to prepare for the next pandemic, said Dr. Anderson, who, God willing, will not be for another 100 years.

Write to Jo Craven McGinty to [email protected]