Inefficiencies in the global distribution of vaccines and the relatively short shelf-life of the leading jabs have meant that doses have arrived in some countries too late for the shots to be used.

The southern African nation of Malawi publicly burnt almost 20,000 doses of the Oxford/AstraZeneca vaccine last month, despite having one of the lowest vaccination rates in the world.

The shots had been marked with an expiry date of April 13 and, although the manufacturer said it would be safe to use the jabs for another three months, the government feared damaging fragile vaccine confidence by administering expired jabs.

“We are destroying publicly in order to stay accountable to Malawians,” said Khumbize Chiponda, the Malawian health minister, who personally placed the red plastic bags of AstraZeneca vials into an incinerator in the capital, Lilongwe.

Last week, South Sudan, which has administered only 8,600 doses, even fewer than Malawi, sent 72,000 doses to Kenya, concerned that it would struggle to give the shots before they expired.

Part of the problem, according to the global vaccine alliance Gavi, is the “extremely cautious” expiry estimates attributed to the main coronavirus shots by manufacturers. The AstraZeneca jab, which must be stored at between 2C and 8C, has a shelf-life of six months. The BioNTech/Pfizer shot can be stored for six months at between -90C and -60C but only lasts up to five days once thawed and refrigerated.

Sinopharm’s vaccine is one exception, with a fridge-temperature shelf-life of 24 months. Most non-coronavirus vaccines have an expiry date of about three years, Gavi says.

In response, several manufacturers are conducting stability tests and requesting extensions to the shelf-life restrictions on their shots to give governments more time.

In April, the Serum Institute of India, in consultation with the African Union, extended the shelf-life of the batch of AstraZeneca vaccines delivered to Malawi, South Sudan and other countries, from April 13 to July 13.

Many of the doses had been stockpiled by Serum last year so they could be shipped once authorised by the World Health Organization, but it left recipient governments with little time to administer the injections.

Amanda Harvey-Dehaye, task force leader at Médecins Sans Frontières for the WHO’s Access to Covid Tools Accelerator, said there needed to be a more transparent discussion about vaccine expiration.

“Given the risk of thousands of doses being destroyed, it’s a shame we have so little visibility over stability tests run by manufacturers — and the subsequent extensions to shelf-life,” she said. “The current expiry dates add real pressure to vaccination campaigns that can already be heavily challenged.”

The WHO says the main issue with expiry dates is potency, just like for small-molecule drugs, rather than safety.

“Synchronising vaccination campaigns with the shelf-life of a vaccine at the time of its arrival in a country is key to facilitating consumption of the supply before they expire,” Cármen Rodríguez Hernández, the group lead for vaccine assessment at the WHO’s pre-qualification unit, told the Financial Times.

Matthew Kavanagh, the director of the Global Health Policy & Politics Initiative at Georgetown university, said the timing of international deliveries was the bigger issue.

“The problem is that companies are not providing sufficient rapid supply of vaccines to African countries,” he said. “The idea that African countries should use the leftovers of high-income countries, including expired doses, is not only deeply unethical but a recipe for vaccine hesitancy.”

That fear has already played out in Malawi, where only 353,000 doses have been administered to date, equivalent to less than two vaccinations per 100 residents.

“It has never been easy to assure people that this vaccine was good for use because there was a lot of propaganda even before we received it,” Chiponda, the health minister, told local media when she incinerated the AstraZeneca doses.

President Lazarus Chakwera’s government is targeting 11m vaccinations overall. Malawi cannot be seen as a “dumping ground” for expired vaccines, the president said last month.

South Sudan’s vaccination programme has been hindered less by public hesitancy and more by local logistical challenges. Limited infrastructure and ongoing fighting in some rural areas have hampered the distribution of doses in the world’s newest country, home to 12m people.

Unable to use all the 132,000 doses of the AstraZeneca shot it received from the Covax vaccine programme in March, South Sudan elected to use the scheme to send a large proportion of the doses to Kenya, where demand for vaccinations is high.

“It’s called the ‘Gavi sharing policy’, [through] which countries that are not utilising their doses, instead of waiting for them to expire, they give [to] their neighbours who can use them,” said Dr Willis Akhwale, head of Kenya’s vaccine task force.

Kenya has already administered 960,000 of the 1.1m vaccines it has received, most of them from Covax. “We were to get the 3.6m doses of AstraZeneca, but we’ve got only 1m,” Akhwale said.

John Nkengasong, the African Union’s disease control unit’s director, said the uptake of vaccinations in many other African countries had been “pretty good”.

“The greatest challenge is the predictability of availability of vaccines to enable planning and community mobilisation.”

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