Worrisome new coronavirus variants can evade antibodies that neutralize original virus
(Asian News Hub) – New research at Washington University School of Medicine in St. Louis indicates that three new, fast-spreading variants of the virus that cause COVID-19 can evade antibodies that work against the original form of the virus that sparked the pandemic.
With few exceptions, whether such antibodies were produced in response to vaccination or natural infection, or were purified antibodies intended for use as drugs, the researchers found more antibody is needed to neutralize the new variants.
The findings, from laboratory-based experiments and published March 4 in Nature Medicine, suggest that COVID-19 drugs and vaccines developed thus far may become less effective as the new variants become dominant, as experts say they inevitably will. The researchers looked at variants from South Africa, the United Kingdom and Brazil.
“We’re concerned that people whom we’d expect to have a protective level of antibodies because they have had COVID-19 or been vaccinated against it, might not be protected against the new variants,” said senior author Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine.
“There’s wide variation in how much antibody a person produces in response to vaccination or natural infection. Some people produce very high levels, and they would still likely be protected against the new, worrisome variants. But some people, especially older and immunocompromised people, may not make such high levels of antibodies. If the level of antibody needed for protection goes up tenfold, as our data indicate it does, they may not have enough. The concern is that the people who need protection the most are the ones least likely to have it.”
The virus that causes COVID-19, known as SARS-CoV-2, uses a protein called spike to latch onto and get inside cells. People infected with SARS-CoV-2 generate the most protective antibodies against the spike protein.
Consequently, spike became the prime target for COVID-19 drug and vaccine developers.
The three vaccines authorized by the Food and Drug Administration (FDA) for emergency use in the U.S. — made by Pfizer/BioNTech, Moderna and Johnson & Johnson — all target spike. And potent anti-spike antibodies were selected for development into antibody-based drugs for COVID-19.
Viruses are always mutating, but for nearly a year the mutations that arose in SARS-CoV-2 did not threaten this spike-based strategy. Then, this winter, fast-spreading variants were detected in the United Kingdom, South Africa, Brazil and elsewhere.
Sparking concern, the new variants all carry multiple mutations in their spike genes, which could lessen the effectiveness of spike-targeted drugs and vaccines now being used to prevent or treat COVID-19. The most worrisome new variants were given the names of B.1.1.7 (from the U.K.), B.1.135 (South Africa) and B.1.1.248, also known as P.1 (Brazil).
To assess whether the new variants could evade antibodies made for the original form of the virus, Diamond and colleagues, including first author Rita E. Chen, a graduate student in Diamond’s lab, tested the ability of antibodies to neutralize three virus variants in the laboratory.
The researchers tested the variants against antibodies in the blood of people who had recovered from SARS-CoV-2 infection or were vaccinated with the Pfizer vaccine.
They also tested antibodies in the blood of mice, hamsters and monkeys that had been vaccinated with an experimental COVID-19 vaccine, developed at Washington University School of Medicine, that can be given through the nose.
The B.1.1.7 (U.K.) variant could be neutralized with similar levels of antibodies as were needed to neutralize the original virus. But the other two variants required from 3.5 to 10 times as much antibody for neutralization.
Then, they tested monoclonal antibodies: mass-produced replicas of individual antibodies that are exceptionally good at neutralizing the original virus. When the researchers tested the new viral variants against a panel of monoclonal antibodies, the results ranged from broadly effective to completely ineffective.
Since each virus variant carried multiple mutations in the spike gene, the researchers created a panel of viruses with single mutations so they could parse out the effect of each mutation.
Most of the variation in antibody effectiveness could be attributed to a single amino acid change in the spike protein. This change, called E484K, was found in the B.1.135 (South Africa) and B.1.1.248 (Brazil) variants, but not B.1.1.7 (U.K.).
The B.1.135 variant is widespread in South Africa, which may explain why one of the vaccines tested in people was less effective in South Africa than in the U.S., where the variant is still rare, Diamond said.
“We don’t exactly know what the consequences of these new variants are going to be yet,” said Diamond, also a professor of molecular microbiology and of pathology & immunology.
“Antibodies are not the only measure of protection; other elements of the immune system may be able to compensate for increased resistance to antibodies.
That’s going to be determined over time, epidemiologically, as we see what happens as these variants spread. Will we see reinfections? Will we see vaccines lose efficacy and drug resistance emerge? I hope not.
But it’s clear that we will need to continually screen antibodies to make sure they’re still working as new variants arise and spread and potentially adjust our vaccine and antibody-treatment strategies.”
The research team also included co-corresponding author Ali Ellebedy, PhD, an assistant professor of pathology & immunology, of medicine, and of molecular microbiology at Washington University; and co-corresponding author Pei-Yong Shi, PhD, and co-first author Xianwen Zhang, PhD, of the University of Texas Medical Branch.
Washington University School of Medicine
CT scan effective tool to detect, determine severity of Covid-19 cases: DAK
(Asian News Hub) – Doctors Association Kashmir (DAK) on Saturday said chest CT scan is an effective tool to detect and determine the severity of Covid-19 cases.
“CT scan helps in diagnosing and predicting the outcome of Covid-19 patients,” said DAK President and influenza expert Dr Nisar ul Hassan.
“More Covid cases are detected with a CT scan of the chest than through RT-PCR,” he said.
Dr Hassan said we see many patients who test negative on RT-PCR test, but show CT features consistent with Covid-19 disease.
“Many infected patients go unreported as only RT-PCR positive cases are reported. We have a large number of patients who test positive through CT, but are not reported,” he said.
Dr Hassan said RT-PCR, which uses swab for the detection of Covid-19 infection has a sensitivity of 60%-70%. That means more than 30% of positive cases may be missed by the test.
“Another swab test which is now widely used is rapid antigen test. It has a sensitivity of around 50 percent, which raises the possibility of missing more than half of the positive cases,” he said.
“Low sensitivity of swab tests implies that many patients with Covid-19 infection may not be identified and consequently are not isolated from healthy population. And these individuals will continue to spread the disease in the community,” he added.
“Studies have shown that CT has a greater sensitivity ranging from 86% and 98% for detecting positive cases, while having a lower false negative rate than the lab tests,” Dr Nisar said
“In a study of 1,014 patients published in the Journal Radiology, researchers in china found that 88% of the patients showed chest CT findings indicative of Covid-19, while RT-PCR test detected only 59 percent of cases. Among those with negative swab test results, 75 percent had positive chest CT findings,” he said.
The DAK President said not only is CT useful in identifying Covid cases, it also tells us about the severity of the disease.
“That would guide treatment and help reduce the risk of death in Covid patients and save lives,” he said.
Scientists have taught bees to smell the coronavirus, can identify a case within seconds
(Asian News Hub) – Scientists in the Netherlands have trained bees to identify COVID-19 through their sense of smell, according to a press release from Wageningen University.
The research was conducted on more than 150 bees in Wageningen University’s bio-veterinary research laboratory.
The scientists trained the bees by giving them a treat – a sugar-water solution – every time they were exposed to the scent of a mink infected with COVID-19. Each time the bees were exposed to a non-infected sample, they wouldn’t get a reward (a process known as Pavlovian conditioning).
Eventually, the bees could identify an infected sample within a few seconds – and would then stick out their tongues like clockwork to collect the sugar water.
Bees aren’t the first animals to detect COVID-19 by scent. Researchers have also trained dogs to distinguish between positive and negative COVID-19 samples from human saliva or sweat with fairly high levels of accuracy. A small German study found that dogs could identify positive COVID-19 samples 94% of the time.
That’s because metabolic changes from the coronavirus make an infected person’s bodily fluids smell slightly different than those of a non-infected person.But researchers still aren’t sure whether animals are the best bet for sniffing out COVID-19 cases outside the lab.
“No one is saying they can replace a PCR machine, but they could be very promising,” Holger Volk, a veterinary neurologist, told Nature.
PCR machines are what lab technicians use to process standard COVID-19 swab tests.
At the very least, certain animals could be useful for identifying COVID-19 in places or countries in which high-tech laboratory equipment is scarce or inaccessible.Wageningen scientists, for instance, are working on a prototype of a machine that could automatically train multiple bees at once, then uses their skills to test for coronavirus aerosols (tiny virus-laden particles) in the surrounding environment.
Delhi hospital study finds 16 per cent vaccinated individuals tested positive for Covid-19
(Asian News Hub) – A small-scale study on 113 healthcare workers who had received at least one vaccine dose at a private hospital in Delhi found that 18 tested positive for Covid but all except one had mild symptoms.
The study, published in the peer-reviewed journal Diabetes and Metabolic Syndrome: Clinical Research and Reviews on May 3, was conducted on employees of the Fortis Centre of Excellence for Diabetes,
Metabolic Diseases and Endocrinology in Delhi.
The participants in the study by researchers at Fortis, National Diabetes, Obesity and Cholesterol Foundation, and Diabetes Foundation (India), New Delhi, included doctors, nutritionists, nurses, paramedical workers, and maintenance staff.
Of the 113 in the study, 107 had received the second dose of the vaccine.
Taken in percentage form, the study found that
breakthrough infections — Covid infection in vaccinated individuals — occurred in 15.9 per cent (18 persons) of the vaccinated individuals and 95 per cent had mild symptoms. Of these, 17 incurred the infection after the second dose and one person. Except one person who required hospitalisation, all others had mild Covid-19 disease, the researchers said.
According to the study, of the breakthrough infections in 18 persons, 17 incurred the infection after the second dose. These 17 had got their second dose after a mean of 34.8 days following the first jab. All were symptomatic with fever and half of them had sore throat and cough.
The study covered 123 employees “ 75 males, 48 females with mean age 42 — 113 of whom were vaccinated. Of them, 28 people had received the
Covaxin vaccine from Bharat Biotech, and 85 the
Covishield preventive from the Oxford/AstraZeneca stable. Covishield, Covaxin and Sputnik V are the three Covid-19 vaccines currently approved for use in India. The three vaccines claim efficacy of 81 per cent, 70 per cent, and 92 per cent respectively.
However, Sputnik V has not yet hit the market. The researchers noted that breakthrough infections after adequate vaccinations are a matter of concern but adequate data on these infections is not available. Vaccines have effectiveness risk of getting Covid-19 infections by 70-90 per cent, and also shield from severe infection. It is possible, therefore, some people who are fully vaccinated against Covid-19 may get Covid-19 infection, the authors of the study said.
They explained that unpublished data from India as well as published reports from other parts of the world indicate these infections are occurring but are rare. In addition, it appears that these breakthrough infections are either asymptomatic or mild in nature, the authors added. The authors acknowledged some limitations of their study: its small sample size, and absence of data on obesity and co-morbid diseases which are important determinants of severity of Covid-19. They also did not test asymptomatic infections.
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