Researchers in Singapore have conducted a study showing that the messenger RNA- (mRNA) based coronavirus disease 2019 (COVID-19) vaccines developed by Pfizer-BioNTech and Moderna are highly effective at protecting against symptomatic and severe disease following infection with the rapidly spreading B.1.617.2 (delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
The team conducted a multi-center retrospective cohort study of vaccinated and unvaccinated individuals who had been admitted to hospital following infection with the B.1.617.2 variant of concern.
“To our knowledge, we provide the first data characterizing the impact of vaccination on virologic kinetics by the B.1.617.2 variant,” writes Barnaby Young from the National Centre for Infectious Diseases in Singapore and colleagues.
The team found that individuals fully vaccinated with either Pfizer-BioNTech’s BNT162b2 vaccine or Moderna’s mRNA-1273 product were significantly less likely to develop moderate or severe outcomes following B.1.617.2 infection than unvaccinated individuals.
Vaccination was associated with fewer symptoms, lower peak biomarkers of systemic inflammation, and better clinical outcomes. It was also associated with a more rapid decline in viral RNA load and a robust serologic response.
“Vaccination remains a key strategy for control of COVID-19 pandemic,” says Young and colleagues.
A pre-print version of the research paper isa available on the medRxiv* server, while the article undergoes peer review.
.jpg "Study: Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine-breakthrough infections: a multi-center cohort study. Image Credit: NIAID")
Variants of concern pose a threat to vaccination efforts
Phase 3 clinical trials of mRNA-based vaccines have demonstrated efficacies of 92% to 95% in preventing symptomatic and severe disease following SARS-CoV-2 infection.
While the mass rollout of these vaccines has reduced infection and mortality rates in many countries, the emergence of SARS-CoV-2 variants containing mutations in the viral spike protein has led to growing concerns regarding increased transmissibility and resistance to vaccine-induced immunity.
The spike protein is the main structure the virus uses to infect cells and a primary target of binding and neutralizing antibodies following natural infection or vaccination.
While variants of concern such as B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma), and B.1.617.2 (delta) have all been shown to exhibit increased transmissibility, the B.1.1.7 and B.1.617.2 strains have also been associated with increased disease severity and hospitalization.
Following the emergence of B.1.617.2 in India, this variant rapidly spread to other countries and had become the most frequently sequenced lineage worldwide by the end of June 2021.
The vaccination program in Singapore
The COVID-19 vaccination program began in Singapore on December 30th, 2020. Free vaccination with either the Pfizer-BioNTech or Moderna product was made available to all Singapore residents, beginning with the elderly and those with high-risk occupations such as healthcare workers.
As of July 19th, 2021, more than 6,837,000 vaccine doses had been administered and approximately 2,792,400 individuals had been fully vaccinated.
What did the researchers do?
Young and colleagues conducted a multi-center retrospective cohort study to characterize the clinical, virologic and serologic features of vaccinated adults with breakthrough B.1.617.2 infection. The results were compared with those of unvaccinated patients who also had B.1.617.2 infection.
Participants were recruited between April 1st and June 14th, 2021, across five study sites: the National Centre for Infectious Diseases, Singapore General Hospital, National University Hospital, Changi General Hospital and Sengkang Hospital.
News
Nanoplastics with environmental coatings can sneak past the skin’s defenses
Plastic is ubiquitous in the modern world, and it's notorious for taking a long time to completely break down in the environment - if it ever does. But even without breaking down completely, plastic [...]
Chernobyl scientists discover black fungus feeding on deadly radiation
It looks pretty sinister, but it might actually be incredibly helpful When reactor number four in Chernobyl exploded, it triggered the worst nuclear disaster in history, one which the surrounding area still has not [...]
Long COVID Is Taking A Silent Toll On Mental Health, Here’s What Experts Say
Months after recovering from COVID-19, many people continue to feel unwell. They speak of exhaustion that doesn’t fade, difficulty breathing, or an unsettling mental haze. What’s becoming increasingly clear is that recovery from the [...]
Study Delivers Cancer Drugs Directly to the Tumor Nucleus
A new peptide-based nanotube treatment sneaks chemo into drug-resistant cancer cells, providing a unique workaround to one of oncology’s toughest hurdles. CiQUS researchers have developed a novel molecular strategy that allows a chemotherapy drug to [...]
Scientists Begin $14.2 Million Project To Decode the Body’s “Hidden Sixth Sense”
An NIH-supported initiative seeks to unravel how the nervous system tracks and regulates the body’s internal organs. How does your brain recognize when it’s time to take a breath, when your blood pressure has [...]
Scientists Discover a New Form of Ice That Shouldn’t Exist
Researchers at the European XFEL and DESY are investigating unusual forms of ice that can exist at room temperature when subjected to extreme pressure. Ice comes in many forms, even when made of nothing but water [...]
Nobel-winning, tiny ‘sponge crystals’ with an astonishing amount of inner space
The 2025 Nobel Prize in chemistry was awarded to Richard Robson, Susumu Kitagawa and Omar Yaghi on Oct. 8, 2025, for the development of metal-organic frameworks, or MOFs, which are tunable crystal structures with extremely [...]
Harnessing Green-Synthesized Nanoparticles for Water Purification
A new review reveals how plant- and microbe-derived nanoparticles can power next-gen water disinfection, delivering cleaner, safer water without the environmental cost of traditional treatments. A recent review published in Nanomaterials highlights the potential of green-synthesized nanomaterials (GSNMs) in [...]
Brainstem damage found to be behind long-lasting effects of severe Covid-19
Damage to the brainstem - the brain's 'control center' - is behind long-lasting physical and psychiatric effects of severe Covid-19 infection, a study suggests. Using ultra-high-resolution scanners that can see the living brain in [...]
CT scan changes over one year predict outcomes in fibrotic lung disease
Researchers at National Jewish Health have shown that subtle increases in lung scarring, detected by an artificial intelligence-based tool on CT scans taken one year apart, are associated with disease progression and survival in [...]
AI Spots Hidden Signs of Disease Before Symptoms Appear
Researchers suggest that examining the inner workings of cells more closely could help physicians detect diseases earlier and more accurately match patients with effective therapies. Researchers at McGill University have created an artificial intelligence tool capable of uncovering [...]
Breakthrough Blood Test Detects Head and Neck Cancer up to 10 Years Before Symptoms
Mass General Brigham’s HPV-DeepSeek test enables much earlier cancer detection through a blood sample, creating a new opportunity for screening HPV-related head and neck cancers. Human papillomavirus (HPV) is responsible for about 70% of [...]
Study of 86 chikungunya outbreaks reveals unpredictability in size and severity
The symptoms come on quickly—acute fever, followed by debilitating joint pain that can last for months. Though rarely fatal, the chikungunya virus, a mosquito-borne illness, can be particularly severe for high-risk individuals, including newborns and older [...]
Tiny Fat Messengers May Link Obesity to Alzheimer’s Plaque Buildup
Summary: A groundbreaking study reveals how obesity may drive Alzheimer’s disease through tiny messengers called extracellular vesicles released from fat tissue. These vesicles carry lipids that alter how quickly amyloid-β plaques form, a hallmark of [...]
Ozone exposure weakens lung function and reshapes the oral microbiome
Scientists reveal that short-term ozone inhalation doesn’t just harm the lungs; it reshapes the microbes in your mouth, with men facing the greatest risks. Ozone is a toxic environmental pollutant with wide-ranging effects on [...]
New study reveals molecular basis of Long COVID brain fog
Even though many years have passed since the start of the COVID-19 pandemic, the effects of infection with SARS-CoV-2 are not completely understood. This is especially true for Long COVID, a chronic condition that [...]
