US blood supply: why the Red Cross just declared a national crisis

The American Red Cross declared only its second-ever national blood supply crisis on 29 July. Red Cross officials said supplies of type O positive blood — the most commonly transfused blood type — had fallen to less than a one-day national reserve as of 27 July.

The organisation, which supplies about 40% of the nation's blood, said the severity of the shortfall had forced it to begin rationing distribution of type O blood to hospitals, reserving it for only the most critical, life-threatening emergencies.

The crisis emerged from two reinforcing trends. Donation rates fell to their lowest summer level in four years even as hospital demand climbed alongside the usual rise in summer trauma cases. The Red Cross says extreme heat, poor air quality and widespread foodborne illness have kept would-be donors away this summer.

Heatwaves discourage people from waiting outdoors to give blood, and poor air quality has had a similar deterrent effect in some regions. On top of that, a wave of foodborne illness has further shrunk the pool of eligible donors, since anyone who is unwell cannot safely donate.

The Red Cross's last national crisis declaration dates back to January 2022, when a surge in Covid-19 cases, winter storms and staffing shortages combined to disrupt blood supplies nationwide. The current crisis stems from a different chain of causes but has produced a similarly critical shortfall.

The practical consequences for hospitals are concrete. When blood banks run low, surgeons may need to postpone non-urgent operations, trauma centres may be forced to prioritise only the most critical cases, and patients who depend on regular transfusions — including those with sickle cell disease or certain cancers — face the risk of delayed treatment.

The Red Cross is calling for urgent donations to ease the crisis, prioritising donors with type O negative blood (the universal donor type) and type O positive. The organisation stresses that scheduling an appointment and becoming a regular donor is the most effective way to maintain stable supply through sudden crisis periods.

Experts point to a structural issue behind blood donation's vulnerability to seasonal swings: summer is traditionally a period when school- and workplace-organised donation drives slow down and holiday schedules reduce donor turnout — precisely when hospital demand rises with traffic accidents and outdoor injuries.

Health system analysts suggest that as climate-driven extreme heat and air-quality events grow more frequent, this kind of seasonal blood-supply volatility could become more common in the years ahead, meaning blood banks will likely need to build more resilient donor bases and more flexible logistics systems.

For now, the message is simple: the Red Cross is urging anyone eligible, particularly first-time donors, to book an appointment at their nearest donation centre, noting that a single unit of donated blood can help save as many as three lives.

Most healthy adults aged 17 or older, weighing at least 110 pounds, are eligible to donate whole blood roughly every eight weeks, with the process itself typically taking under an hour including screening. The Red Cross says walk-ins are welcome where capacity allows, but scheduling ahead helps blood centres plan collection staffing during a shortfall of this scale.