Death was on a stroll through the misty mountains of Wayanad the night Muhammad Ajnas, 28, was driving his Jeep home.
It had been raining continuously for two days in the northern district of Kerala nestled in the Western Ghats, and the villages around his home in Meppadi town had begun to swell. He had driven to Chooralmala village that evening and to nearby hamlet Mundakkai, helping those affected by the downpour. By late night, he began the drive home to Meppadi town, 11 km from Chooralmala.
Just as he reached home, the torrential rains triggered a ferocious landslide. Boulders as big as houses, along with sludge, debris, and uprooted trees came tumbling down, wiping Chooralmala and Mundakkai into nothingness.
Ajnas remembers a busy valley the evening prior to the disaster. He and his friends were making arrangements to shift people from the flood-hit areas. He recalls driving his Jeep through the slushy roads connecting the villages—Meppadi, Mundakkai and Chooralmala.
When the hills came sliding down, Ajnas was almost home. His 53-year-old mother was there alone, waiting for him, and the rush to get to her saved him. He is among the few survivors who last saw the villages intact. However, as news of the scale of destruction came through, he felt that he should return and help.
On that grim night of July 30, 2024, more than 400 people died in the landslides. Thanks to brave rescuers, hundreds were dragged out of the mud and brought back to life.
Ajnas joined the search for his friends and neighbours, digging through layers of wreckage in the desperate hope of finding survivors.
In the midst of the chaos and anguish of identifying known faces buried in the mud, Ajnas received a call at around 5am. He rushed to the hospital—Aster MIMS—to see an overflowing emergency ward—people bleeding, many still covered in mud.
Ajnas wanted to stay at the disaster site, as he knew many he had known and loved remained buried in the valley, some still waiting for rescue. However, he had a greater mission at hand. “When I left, the mountains looked so majestic and strong. I did not expect they would move,” says Ajnas, the screams and cries for help still fresh in his mind.
“The level of catastrophe was such that the doctors were in immense need of blood. I wasted no time and rushed to the hospital to donate as soon as I got the call,” he said.
There was a reason for the health department’s direct call to Ajnas. He is blessed with a rare blood group: O-negative. His blood could save anyone, irrespective of the antibodies that decide their blood group.
As the injured were brought in, his rare O-negative blood became a bridge between certain death and a second chance at life. O-negative donors serve as a vital lifeline during catastrophes, saving lives even when doctors have no time to determine a patient's blood type.
Known as ‘red gold’, O-negative blood types are universal donors; this means their blood can be safely transfused to patients of any blood type.
Only about 4 per cent of the population in India has O-negative blood; the demand remains high.
Apart from disasters like the one in Wayanad, urgent blood transfusions are required for trauma patients and burn victims. In some cases, multiple transfusions are required to stabilise them. This need is equally vital for premature infants, whose developing systems require the safety of O-negative blood.
“A healthy adult can survive a blood loss of up to 30-40 per cent of their total volume (roughly 1.5 to 2 litres) if they receive prompt medical treatment. Losing more than 40 per cent is usually fatal without immediate, aggressive medical intervention like blood transfusion and surgery,” said Dr Nasser Yusuf, a cardiothoracic surgeon.
Arpit Anand, 32, an entrepreneur based in Bengaluru, recalls the time he was called in by a friend as the local private hospital did not have enough blood in stock. “My friend’s wife required an immediate blood transfusion as she suffered extensive bleeding during delivery. The baby was premature. I had to travel from Yeshwanthpur to Kathriguppe in the peak hours of the morning. Bengaluru traffic is hell during those hours. It took around 45 mins to reach Yeshwanthpur, though the distance is only around 12 km from my place. I was almost sure that I wouldn’t be able to save her,” said Anand, who thought he was late for the donation.
“After wishing him the best, I quietly left the hospital. Truth be told, I didn’t want to be around when they broke the news to him,” said Anand.
At around 8 pm that night, I received a call from him, saying that she was out of the woods and that the baby was in the incubator. “My relief was beyond words. It was a great feeling to be a part of her recovery,” recalls Anand, a frequent blood donor.
In transfusion medicine, safety is not assumed; it is meticulously verified, and precision protects life. Generally, our body’s immune system functions like a paranoid security guard—checking every molecule that enters the bloodstream. It responds to invasions with overwhelming force. How then does O-negative evade these barriers?
The O-negative blood type is known to be the chameleon of our circulatory system. Its RBCs lack A, B, and Rh(D) antigens. Since these antigens are absent, it is basically a ghost to the recipient’s immune system. Therefore, our body does not consider it ‘foreign’. Without major surface antigens to trigger immune recognition, O-negative cells slip past every defensive system in our bodies.
Experts say that a single O-negative donation can save up to three lives. In defence and emergency medicine, it is called “liquid time,” as it can be immediately transfused into any patient, regardless of their blood type, buying precious minutes. “O-negative blood carries a legacy of protection written into our biology,” said Dr C. Dhinesh Kumar, senior consultant–Blood Centre and Transfusion, Aster Medcity, Kochi. The blood type O-negative has unique biological traits shaped by evolution, and those traits may have influenced how human populations survived certain diseases over time. “Blood types developed as humans adapted to different environments and pathogens. It being written into our biology emphasises that blood type is genetically inherited, not chosen or acquired,” Kumar said.
In emergency medicine—be it the plane crash in Ahmedabad or the train tragedy in Balasore—when the injured are overflowing casualty wards, O-negative blood is the invisible constant: the reason doctors can act fast.
“O-negative donors form a small fraction of the population, yet their contribution carries an outsized impact. They may never meet the lives they save, but in trauma bays and operating rooms their presence is unmistakable,” said Dr Gaurav Kakkar, senior consultant & lead, neuro-anaesthesia and neurocritical care, Amrita Hospital, Faridabad.
He adds that in the quiet arithmetic of survival, O-negative blood often arrives before names, histories, or consent forms—and that timing makes all the difference. During the earliest phase of trauma care, uncertainty is absolute. “We often do not know who the patient is, what their blood group might be, or how long they have been bleeding. What we do know is that circulation is collapsing and organs are being starved of oxygen,” said Kakkar. “In that moment, O-negative blood becomes a clinical equaliser.”
“It allows us to act immediately, without waiting for identity or compatibility. It does not treat the injury itself, but it keeps the patient alive long enough for treatment to begin,” said Kakkar. There are many cases where the trauma is technically survivable, but only if blood volume is restored quickly. Without that intervention, the window closes rapidly, he adds. “So yes—within those first minutes, O-negative blood can be the difference between a patient remaining salvageable and crossing a point of no return.”
However, for a 'universal donor' like Ajnas, the stakes are higher when it comes to receiving blood. As an O-negative individual, he can never receive any blood from A, B, or AB blood type donors or from any Rh positive donors as well. On the other hand, those with positive blood groups like O+, A+, B+ have the unique ability to accept blood from negative donors. In an emergency, there is no room for error; receiving blood from the wrong donor can be detrimental.
“A blood transfusion between incompatible groups can cause reactions and immune responses that are severe,” said Dr Nikhil M. Kumar, consultant-clinical haematology and haemato-oncology at Rajagiri Hospital in Kochi.
Blood donations are not just about the types. It is further complex, for blood is far more than just crimson fluid. It is a complex, living tissue that serves as the body’s ultimate transport system. Blood is a specialised liquid connective tissue that circulates through the body to maintain life. It consists of cellular components—red blood cells, white blood cells, and platelets—suspended in a straw-coloured liquid called plasma.
Red blood cells use a protein called haemoglobin to transport oxygen to tissues, while white blood cells provide immune defence, and platelets facilitate clotting to prevent blood loss. The specific nature of an individual's blood is determined by antigens, which are protein markers found on the surface of the red blood cells.
These antigens, categorised primarily through the ABO and Rh systems, dictate a person’s blood type and determine their compatibility for transfusion. Because the immune system produces antibodies to identify and attack foreign antigens, the body will reject any blood type that it recognises as incompatible.
There are eight main blood types based on the ABO and Rh systems: A+, A-, O+, O-, AB+, AB-, B+, and B-. Based on prevalence in India, the most common blood type is O+, followed by B+, while the rarest is AB-, followed by A-. AB+ is known as the universal recipient, as individuals with this blood type can receive blood from any group (A, B, AB, or O, whether positive or negative).
Primarily, there are three types of blood donations. “Normally, the red blood cells (RBCs) are donated after conducting tests to determine whether the donor is healthy. Approximately 350-450 ml of blood is taken at one go in the case of RBC donations. Then there are platelet and stem cell donations,” said Kumar.
Platelets form blood clots to help stop bleeding if you are injured. They protect your body from infections and make clots that can stop bleeding after an injury.
In platelet donations, a machine separates platelets from the blood through a process called apheresis and returns the RBCs and plasma to the donor. The collected platelets help cancer patients, transplant recipients, and trauma victims.
Similarly, in the case of stem cell donations, the blood is drawn through a machine that separates the stem cells and returns the remaining blood to the donor. “There is less awareness about platelet or stem cell donations,” added Kumar.
While these various methods of donation support a broad range of medical needs, it is the rare O-negative reserve that remains the most critical asset in the race against time. Dr Kakkar pointed out, given the rarity of O-negative blood, hospitals treat this particular blood group as a strategic reserve. It is not used based on diagnosis alone, but on the urgency and immediacy of risk.
“It is reserved for patients in whom any delay in transfusion would be life-threatening—severe trauma, uncontrolled haemorrhage, or collapse during surgery,” he said.
The demand for blood is relentless, especially in a hospital with a wide range of patients. Therefore, as soon as one individual’s blood type is identified and the transfusion is secured, doctors immediately shift their focus to the next patent in critical need.
“O-ve blood group, being a universal donor group, can be transfused in an emergency to any patient, without the risk of a transfusion reaction. As soon as the recipient’s blood group is identified we shift to that particular blood group. This also helps saving the precious O-ve supply, which is blood bank’s reserve supply,” he added.
These decisions are protocol-driven and ethically grounded. “The guiding principle is not preference, but necessity: it is for those who will not survive the wait,” said Dr Kakkar.
The scarcity of O-negative blood sharpens the clinical discipline. “For O-negative patients, especially in high-risk surgeries or neurocritical care, transfusion planning is meticulous. We focus aggressively on preventing blood loss, correcting clotting abnormalities early, and transfusing only when there is a clear physiological benefit," said Dr Kakkar.
“Scarcity does not mean restriction of care; it means precision in care. Every unit transfused must have a purpose. This approach benefits not only the individual patient but the system as a whole,” he added.
While doctors manage the clinical precision of these reserves, the system ultimately relies on the immediate, selfless response of individuals who carry this rare blood.
Two years ago, Suraj Pandey, 33, received a call at 2am on a Sunday night from his friend; there had been an accident, and the hospital had called for urgent blood donation. The accident involved a bike and a truck. The biker’s condition was critical.
“I had an early flight to catch on Monday morning, as I had to attend a meeting, and I could barely keep my eyes open. But soon I freshened up and reached Fortis Hospital for the donation,” said Pandey, an entrepreneur in Mumbai.
He says that he still can’t forget the mother’s sobs. “She literally fell seeking my help. Her son was also around my age. I assured her that he would be alright and stayed through the day with her. I missed my flight the next day, but it was totally worth it. I got to know that he would live, and I got to see her happiness,” he added.
Rigorous scientific screening is done to ensure that every unit of blood is safe for the recipient.
A series of tests is conducted at the time of the donor screening. However, the authorities don’t wait for the reports to collect blood. Only the haemoglobin level is checked prior to collecting blood, and the sample for viral markers like HIV, HBsAg and Anti-HCV is sent. If the test results come positive, the donor is informed, and the blood is discarded.
While blood compatibility is the first step, organ transplantation involves a more intricate biological 'handshake.' Strict protocols are required to ensure the recipient’s immune system does not reject the donor organ.
"Matching rules for most solid organ transplants, such as the kidney, heart, and liver, generally follow the same principles as blood transfusions. Type O acts as the universal donor, able to donate to any blood type—A, B, AB, and O—though a Type O patient can only receive from another Type O donor," said Dr Kirti Panwar, consultant pathologist, Holy Family Hospital, Delhi.
Conversely, Type AB is the universal recipient, capable of receiving an organ from any blood type but only able to donate to another Type AB individual.
For those with Type A, donation is possible to A or AB recipients, while they can receive from A or O donors.
Similarly, Type B patients can receive from B or O donors. Notably, unlike blood transfusions, the Rh factor typically does not impact organ transplant compatibility.
"When rules are not followed, the impact of incompatibility is swift and devastating, often resulting in hyperacute rejection," she adds.
"If an incompatible organ is transplanted without specialised medical preparation, the recipient’s antibodies (anti-A or anti-B) will immediately attack the organ's blood vessels. This aggressive immune response causes the transplanted organ to fail within minutes or hours, turning a potential second chance at life into a medical emergency," said Panwar.
Patients with Type O blood often face the longest wait list because they can only receive blood from other Type O donors.
"As part of overcoming the incompatibility, in the case of ABO-Incompatible (ABOi), specialised procedures like plasmapheresis (removing antibodies) and desensitisation therapies allow for successful transplants with a long-term survival rate comparable to matched cases. Also, the paired exchange programmes, known as kidney swaps, allow an incompatible donor-recipient pair to “swap” with another pair so that both recipients receive a compatible organ," said Panwar.
She further added that children under two years can sometimes receive ABOi heart or liver transplants because their immune systems have not yet developed strong anti-blood group antibodies. Also, having the same ABO blood group between donor and recipient significantly improves organ compatibility, reducing the risk of hyperacute rejection and graft failure.
ABO identical or compatible transplants are the “gold standard” as they prevent the immune system from attacking foreign antigens on the donor organs. "While compatible, not identical matches (eg, O donating to A) are safe, mismatched organs (ABO-incompatible) require specialised high-risk procedures," she added.
In addition to ensuring the transplant's success, maintaining stable circulation is the primary concern, as uninterrupted blood flow is crucial for sustaining brain health.
Dr Vijayashankar Paramanandam, head, department of neurology, Apollo Hospital, Chennai, says that the brain depends entirely on a continuous supply of blood to receive oxygen and glucose. When blood flow to the brain is reduced or stops, the effects are immediate.
Within seconds, a person may feel dizzy or lose consciousness. If the interruption lasts a few minutes, brain cells begin to suffer damage due to lack of oxygen. Prolonged interruption can result in stroke, permanent brain injury, or coma. This is why sudden blood loss, cardiac arrest, or blocked blood vessels are considered medical emergencies.
"The blood–brain barrier (BBB) is a natural protective membrane that shields the central nervous system (CNS) from harmful toxins and disease-causing pathogens present in the blood. It acts as a highly selective filter—allowing essential substances such as oxygen and nutrients to enter the brain, while preventing harmful agents from crossing into delicate brain tissue," said Paramanandam, who is a movement disorders specialist.
While the BBB is vital for protecting the brain, it can make treatment difficult because many medicines cannot cross it. "To address this, modern medicine uses advanced techniques such as ultrasound and focused ultrasound. These methods can temporarily and safely open the blood–brain barrier, allowing medications to reach targeted areas of the brain. After treatment, the barrier closes again, restoring its protective function. This approach is being explored to improve outcomes in certain neurological disorders," he said.
He added that reduced blood flow to the brain does not always cause sudden collapse—it can also lead to gradual and long-term problems.
People may experience memory loss, poor concentration, slower thinking, mood changes, dizziness, and balance difficulties. Over time, repeated or prolonged reductions in blood supply can increase the risk of stroke, vascular dementia, and permanent neurological disability.
"Even mild but ongoing reductions in blood flow—due to anaemia, heart rhythm disorders, dehydration, or narrowing of blood vessels—can silently affect brain health and quality of life, said Paramanandam.
O-negative blood takes on an even more delicate role in the neonatal intensive care unit, where it serves as the safest lifeline for premature infants.
Though Neha Tyagi, based in Kolkata, does not know her daughter’s donor, for her, he/she is her saviour. “She was premature, born seven weeks before the due date and required immediate blood assistance. I don’t know whose blood it was, but I got to know that she was given O– blood initially before knowing her blood group.” Tyagi’s daughter is now 4 years old.
Samkit Shah, 35, an IT professional who is O-negative, has donated 52 times, and he recalls earlier times when he used to go with his father, also a regular donor.
“I started donating in 2007. My father’s blood group was O+ve, and he used to take me often with him to the blood bank. I was always inspired by this. I wanted to donate blood too, like him; not just that, I wanted to break his record of donations. When I finally broke his record last year, he was very happy,” said Shah.
When Shah wanted to donate like his father, it was not a decision taken on a whim. He had seen the plight of thalassemia patients, who had to undergo blood transfusions every three weeks or so, depending on their condition. “When I was 18, I joined the Red Cross and became a frequent donor. I always wanted to be a part of saving lives. By seeing this child, who had come to the Ahmedabad centre to receive blood, I was deeply moved. We are so fortunate,” he added.
Shah, who has a six-year-old son, said he wants him to follow the same path.
Individual donors like Shah and Ajnas provide a vital lifeline, but with blood reserves still very low, the system relies on a new generation of givers to save a life.
BLOOD TRANSFUSION TODAY
In India among haematological disorders, conditions like thalassemia place a significant and sustained demand on blood transfusion services. These patients often require lifelong transfusion support, sometimes as frequently as every three to four weeks, to sustain vital functions. While ABO and RhD matching remains the primary safety standard, modern transfusion medicine in India is evolving toward extended phenotyping to prevent alloimmunisation (a complication when the patient produces antibodies against donor blood cell antigens) and related complications. Each compatible unit acts as a vital intervention, empowering transfusion-dependent patients to lead active, functional lives.