Archive for the ‘immunology’ Category

Another COVID-19 reinfection: This time second infection was more severe

August 28th, 2020
A nurse practitioner administers COVID-19 tests in the parking lot at Brockton High School in Brockton, MA under a tent during the coronavirus pandemic on Aug. 13, 2020.

Enlarge / A nurse practitioner administers COVID-19 tests in the parking lot at Brockton High School in Brockton, MA under a tent during the coronavirus pandemic on Aug. 13, 2020. (credit: Getty | Boston Globe)

A 25-year-old resident of Reno, Nevada was infected with the pandemic coronavirus, SARS-CoV-2, two times, about 48-days apart, with the second infection causing a more severe case of COVID-19 than the first and requiring hospitalization and oxygen support.

That’s according to a draft study, led by researchers at the University of Nevada and posted online. The study has not been published by a scientific journal and has not been peer-reviewed. Still, it drew quick attention from researchers, who have been examining data from the first confirmed case of a SARS-CoV-2 reinfection, reported earlier this week.

Reinfections with SARS-CoV-2 are not surprising—or even necessarily concerning. From person to person, immune responses to an infection develop along a spectrum, with some people mounting robust, protective responses and others being left with weaker responses. Amid the more than 24.5 million cases worldwide, it is completely expected to find some recovered patients who are not completely protected by their immune responses and are thus vulnerable to reinfection.

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Posted in antibodies, COVID-19, immunology, reinfection, SARS-CoV-2, science | Comments (0)

Dissecting the immune system’s response to COVID-19

August 24th, 2020
Red/Blue/Green fluorescent image of cells.

Enlarge / T-cells attacking a cell recognized as foreign. (credit: NIH)

We're still struggling to understand whether infection with SARS-CoV-2, with our without COVID-19 symptoms, provides protection from further infections. Antibodies are an indicator of immunity and are the easiest aspect of the immune response to track. But data indicates that the generation of antibodies is highly variable, and their production may start fading within months. But there are many other aspects to the immune response, many of them centered on T cells. And here again, the response seems to be extremely complex.

Now, additional studies are coming out looking at other specialized aspects of the immune response. While these results provide some cause for optimism in terms of long-lasting immunity, there remain large numbers of unknowns.

Go with the flow

The two studies we'll look at were enabled by a technique called "flow cytometry" that's proven very useful for studying the immune response. It basically helps researchers get past the biggest issue with these studies: there's an abundance of very similar-looking cells involved in an immune response. While a trained eye can tell a T cell from a macrophage using a microscope, knowing there are T cells doesn't tell us much. Not only would we like to know how many of them there are, we'd need to know what types of T cells are present. T cells may help the production of antibodies, they may kill infected cells, they might be used to remember exposure to pathogens, etc.

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Posted in Biology, COVID-19, immunology, natural killers, SARS-CoV-2, science, t cells | Comments (0)

Healthy 33-yr-old man first to have confirmed reinfection with SARS-CoV-2

August 24th, 2020
People in protective gear pull a gurney.

Enlarge / Medical staff wearing personal protective equipment (PPE) as a precautionary measure against the COVID-19 coronavirus approach Lei Muk Shue care home in Hong Kong on August 23, 2020. (credit: Getty | May James)

A healthy, 33-year-old man in Hong Kong is now the first person in the world confirmed to have been reinfected by the pandemic coronavirus, SARS-CoV-2—which has currently infected more than 23 million people worldwide.

The man’s first infection was in late March. He reported having a cough with sputum, fever, sore throat, and a headache for three days before testing positive for the virus on March 26. Though his symptoms subsided days later, he was hospitalized on March 29 and remained in the hospital until April 14, when he tested negative for SARS-CoV-2 in two tests taken 24-hours apart.

About 4.5 months later, the man tested positive for the virus again. This time, his infection was caught during entry screening at a Hong Kong airport, as he returned from a trip to Spain, via the United Kingdom, on August 15. Though he had no symptoms, he was again hospitalized. Clinical data showed he had signs of an acute infection, but he remained asymptomatic throughout his time in the hospital.

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Meet the 4 frontrunners in the COVID-19 vaccine race

July 23rd, 2020
A volunteer receives an injection from a medical worker during the country's first human clinical trial for a potential vaccine against COVID-19 at the Baragwanath Hospital on June 28, 2020 in Soweto, South Africa. It is reported that Africa's first COVID-19 vaccine trial began on June 24 in South Africa. The vaccine, developed by Oxford University's (UK) Jenner Institute, will inoculate 2,000 South Africans.

Enlarge / A volunteer receives an injection from a medical worker during the country's first human clinical trial for a potential vaccine against COVID-19 at the Baragwanath Hospital on June 28, 2020 in Soweto, South Africa. It is reported that Africa's first COVID-19 vaccine trial began on June 24 in South Africa. The vaccine, developed by Oxford University's (UK) Jenner Institute, will inoculate 2,000 South Africans. (credit: Getty | Felix Dlangamandla)

Researchers have now reported data from early (and small) clinical trials of four candidate COVID-19 vaccines.

So far, the data is positive. The vaccines appear to be generally safe, and they spur immune responses against the novel coronavirus, SARS-CoV-2. But whether these immune responses are enough to protect people from infection and disease remains an important unknown.

The four candidates are now headed to larger trials—phase III trials—that will put them to the ultimate test: can they protect people from COVID-19 and end this pandemic?

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Posted in antibodieis, Astrazeneca, cansino, china, COVID-19, Features, immune system, immune system response, immunity, immunology, moderna, mRNA, Pfizer, public health, SARS-CoV-2, science, vaccines | Comments (0)

CDC finds lots of undetected coronavirus cases in the US

July 22nd, 2020
Image of a person processing biological samples.

Enlarge / A nurse at the Miami Beach Convention Center Community Based Testing Site conducts a COVID-19 antibody test. The Florida Guard is providing support at the Miami Beach hybrid CBTS and Hard Rock Stadium CBTS to allow the state and local partners to conduct antibody testing for first responders at both facilities. (US Army photo by Sgt. Leia Tascarini) (credit: Army Sgt. Leia Tascarini)

It's been clear from quite early in the COVID-19 pandemic that a substantial number of people who get infected by SARS-CoV-2 don't experience significant symptoms. This simple fact has enormous public health consequences, as these asymptomatic individuals can still pass the infection on to others. That means that even if we were able to get everyone with symptoms to self-isolate, we may still be unable to check the spread of the pandemic. It also makes it much harder to find out the true spread of the virus, since many people won't bother to get tested if they aren't feeling unwell.

Most of the data on the spread of the pandemic within the US comes from tests that pick up the presence of the virus' genome, which indicates the presence of an active infection. But you have to catch the person while the infection is happening for this to work. The alternative is to look for an indication of a past infection: the presence of antibodies against SARS-CoV-2. While the immune response to the virus is complex and isn't present immediately after an infection, most people have at least some antibodies a few weeks after the virus is cleared.

This allows widespread antibody testing to provide a clearer picture of the virus' past spread through a population. On Tuesday, the CDC started releasing lots of data from past antibody testing. While it was from a period where the virus was relatively rare in the US, the data provides a sharp contrast to the RNA-based tests from the same time, showing that lots of infections have gone undetected.

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Posted in antibodies, Biology, CDC, COVID-19, immunity, immunology, medicine, pandemic, SARS-CoV-2, science | Comments (0)

Beyond antibodies, the immune response to coronavirus is complicated

July 16th, 2020
Red/Blue/Green fluorescent image of cells.

Enlarge / T-cells attacking a cell recognized as foreign. (credit: NIH)

Ultimately, the only way for societies to return to some semblance of normal in the wake of the current pandemic is to reach a state called herd immunity. This is where a large-enough percentage of the population has acquired immunity to SARS-CoV-2—either through infection or a vaccine—that most people exposed to the virus are already immune to it. This will mean that the infection rate will slow and eventually fizzle out, protecting society as a whole.

Given that this is our ultimate goal, we need to understand how the immune system responds to this virus. Most of what we know is based on a combination of what we know about other coronavirus that infect humans and the antibody response to SARS-CoV-2. But now, data is coming in on the response of T-cells, and it indicates that their response is more complex: longer-lasting, broadly based, and including an overlap with the response to prior coronavirus infections. What this means for the prospect of long-lasting protection remains unclear.

What we know now

SARS-CoV-2 is one of seven coronaviruses known to infect humans. Some of these, like SARS and MERS, have only made the jump to humans recently. While more lethal than SARS-CoV-2, we are fortunate that they spread among humans less efficiently. These viruses seem to provoke a long-lasting immune response following infections. That's a sharp contrast to the four coronaviruses that circulate widely with humans, causing cold-like symptoms. These viruses induce an immunity that seems to last less than a year.

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Posted in Biology, COVID-19, immunology, medicine, SARS-CoV-2, science, t cells | Comments (0)

Antibody testing suggests immune response post-COVID is very variable

June 11th, 2020
Image of a woman finishing a blood donation.

Enlarge / Melissa Cruz elevates her arm after donating COVID-19 convalescent plasma as phlebotomist Jenee Wilson shuts down a machine. (credit: Karen Ducey / Getty Images)

How much of an immune response does a SARS-CoV-2 infection produce? It's a critical question for all sorts of reasons. To begin with, long-lasting immunity, either through an infection or a vaccine, is critical for any hope of returning the world to something that resembles its pre-pandemic state. It's also essential to understanding how safe people who have recovered from infections are and how they can behave in the face of continued outbreaks and spread.

But there are also more subtle public policy issues. Since testing wasn't generally available at the time of many outbreaks, we'll need antibody tests to figure out who was actually exposed. And the accuracy of those tests—which has been called into question—can have a big influence on studies of the pandemic's progression.

A bunch of recent draft papers have looked at the sort of immune response we're seeing in patients who have cleared the virus after testing positive for it. And the results suggest that it's very variable—as is the quality of the tests that detect it. (We'll remind you that pre-publication documents carry some quality risks.)

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FDA: Makers of coronavirus antibody tests must now show tests actually work

May 5th, 2020
Extreme closeup photo of gloved hands holding a test tube.

Enlarge / MAY 4, 2020: A health worker handles a blood sample on the first day of a free COVID-19 antibody testing event. (credit: Getty | Barcroft Media)

After a gush of bogus coronavirus blood tests, the US Food and Drug Administration announced Monday that test makers must submit data within 10 days showing that their tests actually work—or risk getting purged from the market.

The new requirement updates a lax policy the FDA announced March 16, which prioritized providing “regulatory flexibility” to allow these blood tests—aka serology tests—to hit the market quickly during the pandemic. That flexibility came at the expense of normal scientific vetting that ensures those tests meet standards for accuracy and reliability.

“In mid-March, it was critical for the FDA to provide regulatory flexibility for serology test developers, given the nature of this public health emergency... However, flexibility never meant we would allow fraud,” the FDA wrote in a policy update Monday. “We unfortunately see unscrupulous actors marketing fraudulent test kits and using the pandemic as an opportunity to take advantage of Americans’ anxiety.”

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Posted in antibody, blood testing, COVID-19, fda, immunology, infectious disase, public health, SARS-CoV-2, science, seroprevalence, testing | Comments (0)

Injecting the flu vaccine into a tumor gets the immune system to attack it

December 31st, 2019
Injecting the flu vaccine into a tumor gets the immune system to attack it

Enlarge (credit: picture alliance/Getty Images)

A number of years back, there was a great deal of excitement about using viruses to target cancer. A number of viruses explode the cells that they've infected in order to spread to new ones. Engineering those viruses so that they could only grow in cancer cells would seem to provide a way of selectively killing these cells. And some preliminary tests were promising, showing massive tumors nearly disappearing.

But the results were inconsistent, and there were complications. The immune system would respond to the virus, limiting our ability to use it more than once. And some of the tumor killing seemed to be the result of the immune system, rather than the virus.

Now, some researchers have focused on the immune response, inducing it at the site of the tumor. And they do so by remarkably simple method: injecting the tumor with the flu vaccine. As a bonus, the mice it was tested on were successfully immunized, too.

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Posted in Biology, cancer, immunology, medicine, science, vaccines | Comments (0)

Here’s how measles wipes out the immune system’s memory

November 6th, 2019
A child with measles.

Enlarge / A child with measles. (credit: Greene, Charles Lyman)

As every parent knows, kids spend their early years exploring the world with their mouths, gumming every germ-riddled object within reach and sampling their ever-sticky fingers. If left to their own devices, it seems likely they would taste-test door knobs and lick the floors of public bathrooms.

However horrifying, their slobbery ways have an upside—building up immune defenses. Their daily buffet of germs provides their immune systems with thorough intel on countless microscopic enemies. The dirt on the germs is enough to train immune cells to produce Y-shaped blood proteins called antibodies that can detect individual foes based on unique molecular patterns. From there, armies of antibodies act like security guards, surveilling the body for specific, pre-identified threats. Any time they recognize an invader, they can sound the alarm and lead a strike.

Thus, the drool-based defense system arms kids with a bulwark against a wide range of bugs that commonly float around daycares, schools, and beyond. Of course, for some particularly nasty diseases, vaccines do the work of a grimy mitt—safely. They prime the immune system to make antibodies that lead to longstanding protection, sans severe infections.

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Posted in antibodies, biology - immunology, immune cells, immunity, immunology, Infectious disease, measles, science, vaccines, virus | Comments (0)