Coronavirus

Ever since the coronavirus reached the U.S., officials and citizens alike have gauged the severity of the spread by tracking one measure in particular: How many new cases are confirmed through testing each day. However, it has been clear all along that this number is an understatement because of testing shortfalls.

Now a research team at Columbia University has built a mathematical model that gives a much more complete — and scary — picture of how much virus is circulating in our communities.

It estimates how many people are never counted because they never get tested. And it answers a second question that is arguably even more crucial — but that until now has not been reliably estimated: On any given day, what is the total number of people who are actively infectious? This includes those who may have been infected on previous days but are still shedding virus and capable of spreading disease.

The model's conclusion: On any given day, the actual number of active cases — people who are newly infected or still infectious — is likely 10 times that day's official number of reported cases.

The model has not been published or peer-reviewed yet, but lead researcher, Jeffrey Shaman, an infectious disease specialist at Columbia University, shared the data exclusively with NPR. Here are more of the startling takeaways.

Missed cases remain a massive problem

To come up with their bottom line estimate, the researchers' first step was to estimate, for each day of the outbreak so far, how many people actually became infectious. Then they compared that with the number who got tested and counted as a confirmed case.

Levels of protective antibodies in people wane "quite rapidly" after coronavirus infection, say researchers.

Antibodies are a key part of our immune defences and stop the virus from getting inside the body's cells.

The Imperial College London team found the number of people testing positive for antibodies has fallen by 26% between June and September.

They say immunity appears to be fading and there is a risk of catching the virus multiple times.

More than 350,000 people in England have taken an antibody test as part of the REACT-2 study so far.

In the first round of testing, at the end of June and the beginning of July, about 60 in 1,000 people had detectable antibodies.

But in the latest set of tests, in September, only 44 per 1,000 people were positive.

It suggests the number of people with antibodies fell by more than a quarter between summer and autumn.

"Immunity is waning quite rapidly, we're only three months after our first [round of tests] and we're already showing a 26% decline in antibodies," said Prof Helen Ward, one of the researchers.

The fall was greater in those over 65, compared with younger age groups, and in those without symptoms compared with those with full-blown Covid-19.

The number of healthcare workers with antibodies remained relatively high, which the researchers suggest may be due to regular exposure to the virus.

Antibodies stick to the surface of the coronavirus to stop it invading our body's cells, and attract the rest of the immune system.

Exactly what the antibody drop means for immunity is still uncertain. There are other parts of the immune system, such as T-cells, which may also play a role.

However, the researchers warn antibodies tend to be highly predictive of who is protected.

Prof Wendy Barclay said: "We can see the antibodies and we can see them declining and we know antibodies on their own are quite protective.

Many worldwide government leaders are not qualified to manage the handling of a pandemic like Covid-19, and many have made major mistakes for over a year now. We are not here to blame, and we understand that day-to-day government operations do not normally include management of an airborne infectious disease pandemic. So, we ask that, for the benefit of all people everywhere, governments follow these simple but effective guidelines in managing and then eradicating the Covid-19 pandemic. First of all, Join the 10 day simultaneous confinement recommended at 10days.us! Help make it happen and slow covid down immediately!

1) Most importantly, random testing should be done by region, as all other testing is skewed and biased. The only way to know the real rate of increase or decrease of positivity, or past infection, or of a specific mutation or variant in a population is through 100% random testing of the population group. Even a small sample size, if done properly, will give truer results than simply collecting data from those who get tested.

2) Covid only hospitals should be built (in the UK they call them Nightingale hospitals) and all covid patients should be moved there and treated there. This involves building living and sleeping areas on-site for the doctors and nurses who work at the covid hospitals. This will provide a great economy of money and resources, as well as protect existing regular hospitals (which will have a reduced operation and staff as some of their staff will have to move to the covid hospitals). Alternatively, some existing hospital facilities can be turned over 100% to treating covid patiens. Thus no mixing of covid patients and other hospitalized patients occurs and a major vector of transmission is eliminated.

Engineers and doctors say that air cleaning devices could play an important role in protecting your family from COVID-19 — especially as people start spending more time indoors as outdoor air temperatures fall in the Northern Hemisphere.

"It's a relatively easy way to get clean air in a place where people are in close contact," says Joseph Gardner Allen, an associate professor of exposure assessment science who directs the Healthy Buildings program at the Harvard T.H. Chan School of Public Health. "It's a simple plug and play solution in that area." (He bought one in March.)

With new attention on the role that aerosolized microdroplets could play in the spread of COVID-19, should you rush out to buy a portable air cleaner for home use?

The frustrating short answer is, "It depends."

It's accepted that the coronavirus can move in multiple ways, though less is understood about how each contributes to transmission of the disease. Those possible transmission methods include short-range airborne particles, ballistic droplets from coughing or sneezing, long-range airborne particles and contaminated surfaces.

Portable air cleaners can limit the spread of the virus via long-range airborne particles by capturing most of those particles in a HEPA filter and cleaning the air at a rate of up to six times per hour. In a typical home without an air cleaner, the air gets fully changed out about once every two hours through air leakage, often aided by mechanical ventilation systems in newer houses.

So, in the right circumstances, portable air cleaners offer an additional layer of protection.

If you're living by yourself and you don't have guests over, it's not going to add any protection (against COVID-19, anyway ... you may want one to combat cat dander or wildfire smoke).

Poor regulation of antibodies tests - that could indicate if someone has had coronavirus - could be putting the public at risk, doctors have warned.

The U.K. Royal College of Pathologists has written to the health secretary, calling for rules to be tightened on kits sold direct to consumers.

The letter warns they can "mislead the public and put individuals at risk".

No antibodies test has been officially approved for at-home use in the UK - but many different types are available.

It is still not known whether having antibodies will protect people from a second infection.

The doctors say the tests should not be used without "professional back-up", must "give the right result" and be "properly readable".

A Medicines and Healthcare products Regulatory Agency official said it had "worked collaboratively with cross-government agencies at pace to prevent non-compliant antibody test kits being placed into the UK market".

But Royal College of Pathologists president Prof Jo Martin said: "Currently, if you buy a test on the internet or you buy it in certain boutiques or shops, we can't guarantee that the quality of that is of an appropriate standard.

"We can't guarantee that the result will be easy to interpret or that it will be not misleading."

An analysis of 41 antibodies tests sold to the public in the UK, seen by the BBC's Newsnight programme before publication in the medical journal BMJ Open, found almost a third provided incomplete and inaccurate information.

A number claimed to offer "peace of mind".

But just 10% had made documents available to support their claims, academics from the Universities of Birmingham and Warwick found.

What information has been released about how kits were assessed shows most were tested on small numbers of patients only - just a few dozen, all of whom had been admitted to hospital.