New research conducted at Rockefeller’s Laboratory of Molecular Immunology in New York suggests a natural infection may induce maturation of antibodies with broader activity than that conferred by an [mRNA] vaccination. While vaccination produces greater amounts of circulating antibodies than natural infection, the overall antibody response, or memory B cells, birthed from a natural infection are more potent and adapt at eliminating viral variants of pathogens.

In addition, memory B cells produced by vaccination peak and fade within only a few months; those produced by a natural infection evolve over time to protect against severe disease for decades.

Related: Fast-forming, improved antibodies offers long-lasting protection against COVID-19

As to why the antibodies or memory B cells produced by natural infection might be expected to outperform those produced by vaccines, the researchers hypothesise that the immune system may respond differently to viruses that enter through the respiratory tract than those that are injected. It is also possible that the virus persists in the naturally infected for weeks, giving the body more time to mount a robust response. The vaccine, on the other hand, is flushed out of the body mere days after triggering the desired immune response.

In this research, Rockefeller’s Professor Michel C. Nussenzweig and colleagues resolved to tease out any differences in memory B cell evolution by comparing blood samples from convalescent COVID-19 patients to those from mRNA-vaccinated individuals – the latter had never suffered natural infection.

The memory B cells of patients who were vaccinated evolved rapidly to produce increasingly potent memory antibodies. But after two months, progress stalled. The memory B cells were present in large numbers and expressed potent antibodies, but were not getting any stronger. Although some of these antibodies could neutralise the deadly delta and other variants of the coronavirus, there was no overall improvement in breadth of function.

With convalescent patients, on the other hand, memory B cells continued to evolve and improve up to one year after infection. More potent and more broadly neutralising memory antibodies were coming out with every memory B cell update.

Nussenzweig said that memory B cells can be expected to undergo limited volleys of evolution in response to vaccines, a finding that may have significant implications for the design and rollout of booster shots. A booster for the currently available mRNA vaccine(s) would be expected to engage memory cells to produce circulating antibodies that are strongly protective against the original virus and somewhat less so against the variants.

“When to administer the booster depends on the object of boosting: If the goal is to prevent infection, then boosting will need to be done after 6 to 18 months depending on the immune status of the individual. If the goal is to prevent serious disease, boosting may not be necessary for years.”

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A study of the antibodies naturally produced to fight SARS-CoV-2’s spike protein was found to differ from the antibodies of healthy individuals, according to researchers at the University of Reading (Reading), UK. It may also be triggering an exaggerated platelet response, which could lead to fatal blood clots in patients with severe disease.

Platelets are small cells found in blood which form clots to stop or prevent bleeding – it is possible to reduce or stop platelets from overreaction by treating blood with medications that inhibit platelet function or immune responses.  At present, a trial led by Imperial College London and Imperial College Healthcare NHS Trust — called MATIS — is underway testing different drugs in hospitals across the UK to see whether they will reduce serious clotting for patients with a severe COVID-19 infection.

Related: Antibodies against COVID-19 vary with vaccination vs natural infection

“Until now, we have only had assumptions about why platelets involved in clotting were being activated during COVID-19 infection,” said Professor Jon Gibbins, Director of the Institute for Cardiovascular and Metabolic Research at Reading.

“One way to think of what is happens is that the immune response that is designed to protect you from the infection in some cases, particularly in severely ill patients, actually causes more damage. In this case, the antibodies that are produced to stop COVID-19 from spreading trigger infected cells to induce platelet activity which causes clotting even though there is no wound that needs healing.

This new understanding of platelet cell biology provides both support and scientific validation for the MATIS clinical trial, as well as clues as to how unwanted blood clotting may be prevented.

Nichola Cooper, reader at Imperial College London and consultant haematologist at Imperial College Healthcare NHS Trust, supplemented: “Having been involved in early research around blood clotting related to inflammation, it occurred to me that the drugs we already use for other disorders could be easily accessible treatments for COVID-19. We are yet to see results from the MATIS trial so we do not yet know how these drugs will work in patients, but our hope is that we can both inhibit the inflammatory response and prevent severe disease and blood clots. It is exciting to see our collaboration with Reading backing our theory already and providing a solid scientific basis for clinical trials.”

New research has found that the protective antibodies pregnant women make against COVID-19 are often passed on to their foetuses – conveying natural immunity, amongst other benefits. Researchers at Weill Cornell Medicine also suggest that vaccinating mothers-to-be may also have benefits for their newborns.

According to Dr. Yawei Jenny Yang, an assistant professor of pathology and laboratory medicine at Weill Cornell Medicine,blood samples from 88 women who gave birth at New York-Presbyterian/Weill Cornell Medical Center between March and May 2020 had traces of COVID-19 antibodies. This indicated all the women had contracted the virus at some point, even though 58% of those women had no symptoms.

Furthermore, while antibodies were detected in both symptomatic and asymptomatic women, the researchers observed that the concentration of antibodies was significantly higher in symptomatic women. They also found that the general pattern of antibody response in pregnant women was similar to the response seen in the larger patient population in other patients.

In addition, 78% of the babies born to these women had detectable antibodies in their umbilical cord blood. There was no evidence that any of the infants had been directly infected with the virus and all were COVID negative at the time of birth, further indicating that the antibodies had crossed the placenta — the organ that provides oxygen and nutrients to a growing baby during pregnancy — into the foetal bloodstream. Newborns with symptomatic mothers also had higher antibody levels than those whose mothers had no COVID symptoms.

This implies that pregnant women could pass along vaccine-generated antibodies in the same way, potentially shielding both mother and child from future infection.

Dr. Laura Riley, chair of the Department of Obstetrics and Gynecology at Weill Cornell Medicine, obstetrician and gynecologist-in-chief at New York-Presbyterian/Weill Cornell and one of the study’s co-authors, is still advising pregnant patients who decide to get vaccinated to continue to follow current safety guidelines to prevent the spread of the disease.

Dr. Riley, Dr. Yang and their colleagues are currently enrolling pregnant women who receive the vaccine, as well as vaccinated mothers who are breastfeeding, to assess the antibody response in those groups after vaccination, to help guide maternal vaccination strategies moving forward.

University of Leeds research has shown how microbubbles deliver powerful cancer drugs can be guided to the site of a tumor using antibodies.

Microbubbles are small manufactured spheres half the size of a red blood cell and scientists believe they can be used to transport drugs to highly specific locations within the body.  

Lead researchers from the  School of Medicine, describe how they targeted microbubbles through the use of a navigational aid – antibodies attracted to the growth hormone found in high levels in the blood vessels supplying a tumor. 

The antibodies were attached to the microbubbles. As a result of being attracted to the growth hormone, the microbubbles became concentrated at the site of the tumor. A pulse from an ultrasound device was used to burst open the microbubbles, and that released the anti-cancer agent.

Read: UK to develop new treatments for cancer drug resistance

The study was conducted on animals, which were used as a model to try and develop this technique for use in humans.

The study also revealed that attaching the drug directly to the microbubbles allowed it to circulate in the body for longer, increasing delivery into the tumor, in effect making the drug more potent.  As a result, the scientists were able to slow cancer growth with a much smaller drug dose.  

The next stage of the research is to look at using microbubbles to develop targeted, triggered, delivery systems in patients for the diagnosis and treatment of advanced colorectal cancer.

An autoimmune antibody circulating through the blood is attacking healthy cells and has been found to cause microscopic blood clots in people hospitalised with COVID-19, according to scientists at Michigan Medicine Frankel Cardiovascular Center (Michigan Medicine), US. In COVID-19, clots may restrict blood flow in the lungs, impair oxygen exchange, and ultimately cause life-threatening complications such as strokes in people already struggling with the disease.

These clot-causing antibodies are typically seen in patients who have the autoimmune disease antiphospholipid syndrome, so it was quite unexpected that the antibodies could be a culprit in COVID-19 clotting and inflammation; at least half of COVID-19 patients exhibited a combination of high levels of the antibodies and destructive neutrophils, which explode white blood cells – the scientists were first to report the incidence of higher levels of neutrophil extracellular traps in the blood and severe COVID-19.

The scientists also studied the dangerous combination further in mouse models, only to find a striking amount of clotting in animals who received antibodies from patients with active COVID-19 infection.

“[The antibodies] created some of the worst clotting we’ve ever seen,” said Yogen Kanthi, an assistant professor Michigan Medicine. Kanthi and colleagues at Michigan Medicine now want to know whether severely ill patients with high levels of these antibodies would have better outcomes if the antibodies are blocked or removed.

If so, that might warrant an aggressive treatment like plasmapheresis, commonly used for severe autoimmune diseases. Internal medicine specialist Yu Zuo explained that plasmapheresis involved draining a patients’ blood through an IV, filtering it and replacing it with fresh plasma that doesn’t contain antibodies associated with blood clots.

The scientists suggest using convalescent plasma and anti-clotting agents as possible COVID-19 treatments – they are currently testing a well-known anti-clotting agent, dipyridamole, in patients with COVID-19 to see if it can reduce excessive blood clots.

“FDA-approved dipyridamole is an old drug that is safe, inexpensive, and scalable. We only recently discovered its potential to block this specific type of inflammation that occurs in COVID,” said Kanthi.