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Fever, cough, shortness of breath, fatigue, giddiness, and lack of taste are some of the symptoms seen.
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In early 2021, as COVID-19 vaccines were being rolled out across the world, reports began to surface of a rare but alarming complication. Some people who received the shots were developing unusual blood clots. The cases were first identified in Europe and later in the U.S.

Notably, they were reported mainly among recipients of the AstraZeneca and Johnson & Johnson vaccines. The common link between those two vaccines was their design. Unlike the Pfizer and Moderna shots, which used mRNA, both the AstraZeneca and Johnson & Johnson vaccines used a modified virus to deliver DNA into the body’s cells. In roughly 3 to 10 cases per million vaccinated individuals, depending on age and sex, recipients developed unusual blood clots accompanied by low platelet counts, a condition that came to be known as vaccine-induced immune thrombocytopenia and thrombosis (VITT).

Very soon, research groups started reporting that the affected patients were producing antibodies against a human protein called platelet factor 4 (PF4). PF4 plays an important role in regulating the formation of blood clots. In these patients, antibodies were binding to PF4 and forming a complex that activated platelets, driving both clot formation and the low platelet counts.

However, the puzzling thing was PF4 is a human protein. The immune system is not supposed to make antibodies against self-proteins. In extremely rare cases, autoimmune reactions do occur due to genetic susceptibilities, but here, the vaccines were designed to generate immunity against the coronavirus spike protein, not against PF4. How could this be happening?

Delivering the recipe

At its core, a vaccine is essentially a decoy. It presents the immune system with something that looks like the enemy, so the system learns to recognise and defeat the real thing later. The goal of the COVID-19 vaccines was to teach the immune system to recognise the coronavirus’ spike protein. The vaccines do not contain the coronavirus itself. Instead, they deliver instructions that prompt our bodies’ own cells to briefly produce a harmless piece of the virus. The immune system sees this protein, mounts a response, and forms memory cells that stand ready for future encounters.

Cells store DNA inside a structure called the nucleus. When a protein needs to be made, the cell first creates a temporary working copy called messenger RNA (mRNA). The mRNA then exits into the main body of the cell, where special molecular machines called ribosomes make the protein from the mRNA. The mRNA is short-lived and quickly degraded.

mRNA vaccines such as Pfizer and Moderna took advantage of this system by delivering mRNA directly, packaged inside lipid (fat) particles. The mRNA never needed to enter the nucleus: it was immediately read in the cell body to produce the spike protein.

Delivering DNA is more complicated. DNA must enter the nucleus for the cell to make mRNA, which means crossing an additional protective barrier. Injecting naked DNA is inefficient.

Unique antibodies

Viruses, on the other hand, are experts at delivering DNA into cells. AstraZeneca and Johnson & Johnson used a harmless, genetically modified adenovirus as a courier to efficiently carry the coronavirus spike-encoding DNA into the nucleus, from where the cell’s own machinery took over.

Once the cell made the spike protein, it was displayed to the immune system, which began to respond. Among the first responders were B cells, the antibody-producing cells of the body. Each B cell carries on its surface a unique receptor, generated by a remarkable process of genetic reshuffling. During B-cell development, segments of DNA are randomly cut and pasted together in different combinations, creating millions of possible antibody designs. This process ensures enormous diversity even before an infection occurs.

When a B cell receptor recognises the spike protein, it is activated and begins to multiply. As it divides, its antibody genes undergo further fine-tuning through small mutations. Variants that bind the target more tightly are preferentially selected in a kind of microscopic evolutionary competition. Over days to weeks, this iterative cycle produces antibodies of increasing strength and specificity.

In theory, because this system relies on random recombination and mutation, every person’s antibodies are somewhat unique, even when facing the same virus.

Same single mutation

This is generally true for most antibodies. However, a new exception to this rule has been at the core of identifying the cause behind the anti-PF4 antibodies from patients with VITT. In a paper in the New England Journal of Medicine, investigators reported that antibodies isolated from patients from different countries — with no known connection to one another — were remarkably similar at the molecular level. These antibodies weren’t just targeting the same protein: they were built using the same antibody gene segments and carried highly similar structural features.

Even more intriguing: nearly all the affected patients shared one of two versions of an antibody gene, designated IGLV3-21*02 or *03. Additionally, in the process of fine-tuning, all the patients had generated the same single mutation, which led to a small change in the protein. This change, when coupled with the variations in two versions of the antibody genes, altered the electrical charge on that part of the antibody that binds to its target.

When researchers recreated these antibodies in the lab, they showed that this small alteration made a big difference. With the change, the antibodies stuck strongly to PF4 and activated platelets. When the change was reversed, the antibodies bound weakly and were far less likely to trigger clotting.

The researchers then turned to the next question: why this reaction occurred only with vaccines that used an adenovirus as the delivery vehicle. The answer to that lay inside the virus itself.

Cast a shadow

A protein within the adenovirus, called protein VII, contains a short stretch that closely resembles part of PF4. To the immune system, the entire adenovirus particle used for delivery was foreign and antibodies were naturally generated against its components. This is a known effect of these vaccines, and in almost all cases it is harmless. In mounting this response, the immune system first produced antibodies against protein VII. But as these antibodies were being refined, that critical change, in those individuals carrying one of the two specific antibody gene variants, altered their binding properties. As a result, the antibodies were mistaking PF4 for the viral protein and were reacting against the body’s own proteins instead.

For years, the mechanism behind VITT cast a shadow over adenoviral vector vaccines — a technology that has otherwise been central to global immunisation efforts. The new study has provided a clear molecular explanation by identifying protein VII to be the trigger and defining the precise antibody features involved. In so doing, the study’s authors — from Australia, Canada, Germany, and the Netherlands — have paved the way for future vaccines to be engineered even more carefully, further strengthening the safety of adenoviral vectors.

Arun Panchapakesan is an assistant professor at the Y.R. Gaitonde Centre for AIDS Research and Education, Chennai.

Published – March 10, 2026 07:15 am IST

New York:

The Central Intelligence Agency has assessed that the COVID-19 pandemic is “more likely” to have emerged from a lab rather than from nature, an agency spokesperson said on Saturday.

The agency had for years said it could not conclude whether COVID-19 was the result of a lab incident or it originated in nature. But in the final weeks of the Biden administration, former CIA Director William Burns asked CIA analysts and scientists to make a clear determination, stressing the pandemic’s historical significance, according to a senior US official.

The CIA says it has “low confidence” in its assessment that a “research-related origin of the COVID-19 pandemic is more likely” and notes in its statement that both scenarios – lab origin and natural origin – remain plausible.

The Chinese embassy in Washington did not immediately respond to a request for comment.

It was unclear the extent to which the agency has collected new intelligence on COVID-19’s origins and whether that new evidence was used to formulate the latest assessment.

China’s government says it supports and has taken part in research to determine COVID-19’s origin, and has accused Washington of politicizing the matter, especially because of efforts by U.S. intelligence agencies to investigate.

Beijing has said claims that a laboratory leak likely caused the pandemic have no credibility.

In an interview with Breitbart following his confirmation by the U.S. Senate on Friday, CIA Director John Ratcliffe said one of his first priorities was getting his agency to make a public assessment on the pandemic’s origins.

“That’s a day-one thing for me,” he said. “I’ve been on record as you know in saying I think our intelligence, our science, and our common sense all really dictate that the origins of COVID was a leak at the Wuhan Institute of Virology.”

(Reporting by Erin Banco; Editing by Daniel Wallis)

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

New Delhi:

Women might be at a 31 per cent higher risk of developing long Covid compared to men, with those aged 40-55 years likely to be at most risk, a study has found.

Among the women aged 40-55 years, the risk of long Covid was found to be even higher — 42 per cent in menopausal women and 45 per cent in non-menopausal women — the results of the ‘RECOVER’ trial, published in The Journal of the American Medical Association (JAMA) Network Open showed.

Long Covid is estimated to affect about a third of those once infected with Covid-19, with symptoms, such as fatigue and brain fog, persisting well beyond the acute recovery period. The condition, including its causes and treatments, continues to be studied around the world.

Researchers, led by those at The University of Texas, US, followed more than 12,200 people (73 per cent of women), who reported their symptoms while responding to questionnaires at their first study visit at least six months after infection. The participants were enrolled between October 2021, and July 2024.

The trial showed that all women, except those aged 18-39 years, had a 31 per cent higher risk of long Covid — regardless of race, ethnicity, Covid variant and severity of the viral infection.

The study helps identify risk factors for long Covid critical for preventing and treating the often debilitating disease, according to lead researcher Thomas Patterson, a professor of medicine and chief of the division of infectious diseases, school of medicine, The University of Texas.

The researchers added that biological processes contributing to sex-specific differences of long Covid need to be identified that can help develop targeted drugs and improve management of the condition.

“These findings show that patients and health care teams should consider the differences in long COVID risk as it relates to sex assigned at birth,” corresponding author Dimpy Shah, an assistant professor of population health sciences at The University of Texas, said.

“Understanding these differences can help us recognise and treat patients with long Covid more effectively,” Shah said.

While previous studies have shown women to have a tendency for post-viral and autoimmune conditions, it is not clear if the same is true for long Covid, especially within different age groups, the researchers said.

“This study gives us new knowledge and builds on other studies that also looked at sex assigned at birth and long Covid,” Shah said.

“Because of the size of the RECOVER study and the diversity of participants, we had a special opportunity to look at sex assigned at birth while also considering things like vaccination status, autoimmune disease, diabetes, BMI and Covid variant,” the corresponding author said.

(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)

Guwahati:

A 10-month-old child has been detected with the human metapneumovirus (HMPV) infection, the first such case this season in Assam, officials said today.

The child is “stable” and is undergoing treatment at Assam Medical College and Hospital (AMCH) in Dibrugarh.

AMCH superintendent Dhrubajyoti Bhuyan said the child was admitted to the state-run hospital with cold-related symptoms four days ago.

“The HMPV infection was confirmed yesterday after we got test results from the Lahowal-based ICMR-Regional Medical Research Centre (ICMR-RMRC),” he said.

He also said samples are sent to the Indian Council of Medical Research (ICMR) for tests in influenza and flu-related cases as a routine practice.

“It was a routine test during which the HMPV infection was detected. The child is stable now. It is a common virus and there is nothing to worry about,” he said.

A senior official at the ICMR-RMRC in Lahowal said it was the first HMPV case this season. 

“Since 2014, we have detected 110 HMPV cases in Dibrugarh district. Every year it is detected, and nothing is new. We have got the sample from AMCH and this has been found positive for HMPV,” he was quoted as saying by the news agency PTI. 

HMPV Virus Is Similar To Flu, Not Like Covid

The HMPV is a respiratory virus and has recently gained attention after its outbreak in China. Experts, however, have dismissed fears that the situation is comparable to the beginnings of Covid-19 five years ago.

First discovered in 2001, it generally causes a mild infection of the upper respiratory tract and spreads via person-to-person contact or when someone touches a contaminated surface.

HMPV’s common symptoms include coughing, fever and a blocked nose — very similar to many types of cold and flu.

Vulnerable groups such as young children, the elderly and people with compromised immune systems may develop more severe symptoms.

The rise in cases of a respiratory virus in China have raised concerns reminiscent of the early days of the Covid-19 pandemic, which began nearly five years ago. However, experts assure that despite the similarities, the current situation is very different and less alarming. The virus causing the infections in China is identified as human metapneumovirus (HMPV). It has now spread to India, bringing the total number of cases here to seven. Meanwhile, reports indicate that the US and UK are facing a “quad-demic,” with four different viruses spreading simultaneously, placing significant pressure on healthcare services.

According to Fortune magazine, flu, Covid, respiratory syncytial virus (RSV), and norovirus are making their winter rounds in the United States, and you may have heard the term “quad-demic” pop up online or in conversation (the first three are sometimes called a “triple-demic”). While the unofficial term for the four maladies circulating in tandem evokes a sense of impending doom, the quadruple threat isn’t so different from respiratory virus seasons past.

“All of the viruses are here; it’s just they’re affecting different areas a little bit differently,” Dr Robert Hopkins Jr, medical director of the National Foundation for Infectious Diseases, tells Fortune. “I don’t want to panic people, but I would say if you haven’t been vaccinated and you’re eligible for vaccination-that means everybody 6 months of age and older-get that Covid shot, get that flu shot.”

Sky News also reported that four illnesses are circulating in the UK this winter in what has been dubbed the “quad-demic.” NHS leaders have issued a warning that cases of flu, norovirus, and respiratory syncytial virus (RSV) are increasing, with a rise in Covid-19 also expected. Data released by the health body showed an average of 1,861 patients with flu were in the hospital every day in the first week of December-a 70% increase from the previous week when there were 1,099 patients. The number was also 3.5 times higher than the same time last year.

Norovirus (the winter vomiting bug) and RSV (a common cause of a type of chest infection in babies) are also on the rise. Cases of norovirus were up 10% on the previous week and 64% on last year, while 152 children were in the hospital with RSV each day-up from 107 this time in 2023.

Professor Sir Stephen Powis, national medical director for NHS England, told Sky News: “The tidal wave of flu cases and other seasonal viruses hitting hospitals is really concerning for patients and for the NHS-the figures are adding to our ‘quad-demic’ worries.”

What is the ‘quad-demic’?

The term “quad-demic” refers to the “four very common viral illnesses that circulate every winter in different peaks,” Dr David Lloyd, an NHS GP, told Sky News Breakfast last month. The risk and complication rate of people catching all four of these illnesses at once heightens at this time of the year, hence the term, he added.

Merck & Co’s Covid-19 antivirals are getting a new lease of life in post-pandemic China, as cat owners seize on them as antidotes to a life-threatening disease caused by a coronavirus that infects their feline companions.

People are feeding their furry friends Merck’s Lagevrio to treat Feline Infectious Peritonitis, a fatal disease that until recently had no readily available treatment, local media outlet Jiemian reported this week.

The move has been a hot topic on social media, with tens of thousands of cat lovers taking to Xiaohongshu, China’s version of Instagram, to discuss how the drugs saved their pets, along with money on expensive veterinary bills.

“Covid-19 drugs for humans saved my cat’s life,” one user wrote on Xiaohongshu. “I share the notes here to teach more people to save their furry babies and reduce the pain suffered by cats.”

In addition to the foreign antivirals, some pet owners also have opted for similar but cheaper Covid medicines developed by homegrown companies including Henan Genuine Biotech Co., Simcere Pharmaceutical Group Ltd. and Shanghai Junshi Biosciences Co.

A spokesperson for Merck said in an emailed response to Bloomberg News that the company hasn’t tested the drug on cats and has no plans to do so.

Chinese pet owner’s use of human Covid drugs on animals is in stark contrast to the early days of the pandemic, when the use by people of ivermectin in the US – a drug to treat parasitic worms in animals – prompted the US Food and Drug Administration to post the words of caution: “You are not a horse. You are not a cow. Stop it.”

Feline Infectious Peritonitis is a viral disease caused by the so-called feline coronavirus that infects white blood cells before spreading throughout a cat’s body, causing inflammatory reactions. The disease is fatal without treatment. FIP is unique to cats, and not contagious to people, dogs, or other animals.

No specific treatment was available until recently. Some antiviral drugs have proved to be effective, but they aren’t widely accessible. The most popular, GS-441524, developed by Gilead Sciences, hasn’t been approved by the FDA, and cat owners often seek the drug through black market sources.

Chinese cat owners have to rely on informal networks to purchase GS-441524, which often cost tens of thousands of yuan. On Chinese social media, many people complain the drug is too expensive and that many black market sellers gave them a fake version.

Human Covid antivirals are much more affordable, they said. A 40-pill bottle of Lagevrio, for example, costs about 1,725 yuan ($236) online, and is enough to treat more than one cats. In addition to the drugs, Chinese cat owners also feed their pets nutritional supplements developed for humans, because they are cheaper than veterinary drugs.

“I don’t understand why medicines for pets are so expensive,” wrote one Xiaohongshu user. “You just need to adjust the dosage of human medicines if you are going to use them on cats.”

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Beijing, China:

Beijing insisted on Tuesday that it had shared information on Covid-19 “without holding anything back”, after the World Health Organization implored China to offer more data and access to understand the disease’s origins. Covid-19, which first emerged in the central Chinese city of Wuhan in December 2020, went on to kill millions of people, shred economies and overwhelm health systems.

The WHO published a statement on Monday saying it was a “moral and scientific imperative” for China to share more information.

In response, China defended its transparency, saying it had made the “largest contribution to global origin tracing research”. 

“Five years ago… China immediately shared epidemic information and viral gene sequence with the WHO and the international community,” foreign ministry spokeswoman Mao Ning said. 

“Without holding anything back, we shared our prevention, control and treatment experience,” she told reporters at a regular press briefing.

But over the course of the pandemic, the WHO repeatedly criticised Chinese authorities for their lack of transparency and cooperation.

A team of specialists led by the WHO and accompanied by Chinese colleagues conducted an investigation into the pandemic’s origins in early 2021. 

In a joint report, they favoured the hypothesis that the virus had been transmitted by an intermediary animal from a bat to a human, possibly at a market. 

A team has not been able to return to China since, and WHO officials have repeatedly asked for additional data. 

Mao said Tuesday that “more and more clues” pointed “to Covid-19’s origins having a global scope”.

China was “willing to continue working with various parties to promote global scientific origin tracing, and to make active efforts to prevent potential infectious diseases in the future”, she said.

Pandemic preparedness

This month, WHO Director-General Tedros Adhanom Ghebreyesus said “the world would still face some of the same weaknesses and vulnerabilities that gave Covid-19 a foothold five years ago”, if a new pandemic emerged today.

“But the world has also learnt many of the painful lessons the pandemic taught us, and has taken significant steps to strengthen its defences against future epidemics and pandemics,” he said.

In December 2021, spooked by the devastation caused by Covid, countries decided to start drafting an accord on pandemic prevention, preparedness and response.

The WHO’s 194 member states negotiating the treaty have agreed on most of what it should include, but are stuck on the practicalities. A key fault line lies between Western nations with major pharmaceutical industry sectors and poorer countries wary of being sidelined when the next pandemic strikes.

While the outstanding issues are few, they include the heart of the agreement: the obligation to quickly share emerging pathogens, and then the pandemic-fighting benefits derived from them such as vaccines.

The deadline for the negotiations is May 2025.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)

Geneva:

The World Health Organization on Monday implored China to share data and access to help understand how Covid-19 began, five years on from the start of the pandemic that upended the planet.

Covid-19 killed millions of people, shredded economies and crippled health systems.

“We continue to call on China to share data and access so we can understand the origins of Covid-19. This is a moral and scientific imperative,” the WHO said in a statement.

“Without transparency, sharing, and cooperation among countries, the world cannot adequately prevent and prepare for future epidemics and pandemics.”

The WHO recounted how on December 31, 2019, its country office in China picked up a media statement from the health authorities in Wuhan concerning cases of “viral pneumonia” in the city.

“In the weeks, months and years that unfolded after that, Covid-19 came to shape our lives and our world,” the UN health agency said.

“As we mark this milestone, let’s take a moment to honour the lives changed and lost, recognise those who are suffering from Covid-19 and Long Covid, express gratitude to the health workers who sacrificed so much to care for us, and commit to learning from Covid-19 to build a healthier tomorrow.”

‘Same weaknesses’

Earlier this month, the WHO’s Director General Tedros Adhanom Ghebreyesus addressed the issue of whether the world was better prepared for the next pandemic than it was for Covid-19.

“The answer is yes, and no,” he told a press conference.

“If the next pandemic arrived today, the world would still face some of the same weaknesses and vulnerabilities that gave Covid-19 a foothold five years ago.

“But the world has also learnt many of the painful lessons the pandemic taught us, and has taken significant steps to strengthen its defences against future epidemics and pandemics.”

In December 2021, spooked by the devastation caused by Covid, countries decided to start drafting an accord on pandemic prevention, preparedness and response.

The WHO’s 194 member states negotiating the treaty have agreed on most of what it should include, but are stuck on the practicalities.

A key fault-line lies between Western nations with major pharmaceutical industry sectors and poorer countries wary of being sidelined when the next pandemic strikes.

While the outstanding issues are few, they include the heart of the agreement: the obligation to quickly share emerging pathogens, and then the pandemic-fighting benefits derived from them such as vaccines.

The deadline for the negotiations is May 2025.

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)