The World Health Organisation has warned that another challenge is looming in the effort to vaccinate the planet against the coronavirus: a shortage of syringes.
There could be a shortfall of one to two billion syringes next year, WHO specialist Lisa Hedman said on Tuesday in Geneva.
Poorer countries, which often place small orders and therefore do not have priority with manufacturers, could be particularly affected.
The WHO is calling on countries to plan ahead and order in large amounts, if possible, and pay heed that six months' lead time in often necessary for manufacturers.
In a normal year, 16 billion injections are given worldwide, according to WHO estimates.
Before the pandemic, vaccinations accounted for 5 to 10 per cent of that, or up to 1.6 billion.
But an additional 6.8 billion doses of COVID-19 vaccine have now been given worldwide, vastly increasing the demand for syringes, according to WHO estimates.
Syringes for vaccinations differ from those for other purposes.
They usually have a mechanism that ensures that they are used only once.
According to WHO estimates, manufacturers can produce about six billion of those syringes a year.
The largest export countries are India and China, it said.
Next year's demand could be four to seven times higher than the average pre-pandemic demand.
If there are not enough vaccine syringes, routine jabs such as against measles, mumps and rubella may have to be foregone, Hedman said.