Why smaller vials of vaccine might help Zambia expand measles coverage

Registered nurse Memory Mwezi has been serving at Mwimba Health Post’s daily health clinics for long enough to have a pretty good sense of the ebbs and flows of patient demand. Fridays, for instance, are rarely busy at the small government health facility in Eastern Zambia’s Lumezi District. 

But this particular Friday happened to fall on the first day of a new month, and that meant Mwezi was somewhat run off her feet. “People usually come the most at the end and start of the month,” she told me, once the crowd of little patients and their guardians had dwindled.

The children seen by the clinic range in age from zero months to five years of age, and as such, Mwezi had spent the morning administering a spread of jabs from up and down Zambia’s routine immunisation schedule. But I had reached out with questions about just one of them – and for a reason that sounds deceptively trivial.

Not such a small change

Last year, Zambia began to use measles-rubella (MR) vaccines that came in a new format. Instead of the usual ten-dose vials of the MR combo, health centres including Mwinda Health Post began stocking five-dose MR vials. There was good research suggesting that the switch was a small shift that could make an outsize difference. I wanted to know whether Mwezi was seeing signs of a change.

“It’s common for us to have two to four children on some days for measles vaccination,” she told me. “When we still had the stock of the ten-dose vials, I would usually send people back home, especially when the stock was limited.”

Vaccine vials, once opened, can’t be stoppered up again and put away, so opening a vial of measles vaccine on a two-child clinic day would mean losing eight doses, she explained.

Though both the World Health Organization (WHO) and the Zambian health system recommend that vaccine vials be opened even if just one child is present, to avoid missing any chance to protect children, wasting vaccine is something health workers often do reluctantly – especially when inventory is low, said Mwezi. 

But that meant the patients who had to be asked to return on a day with a higher turnout risked being missed out. “You would find that the coverage was not good. But that has changed with the five-dose vials,” Mwezi said.

Mwezi said she has also seen similar changes in community outreaches – mobile vaccination sessions that take place closer to the community in the harder-to-reach parts of the district. “I have noticed that we have more stock with the five-dose vials, so I am not scared to open a vial even with less than five patients who can’t take up the entire dosage. It is a relief as our coverage numbers are better,” she said.

Rahab Mbewe, an Environmental Health Technologist at Chanyalubwe Health Post in Eastern Zambia – whose job includes surveillance of health programmes – echoes Mwezi’s experience with the smaller vials of MR vaccine.

“There was a time we went for outreach immunisation – these outreach immunisations are actually 32 kilometres from the facility – so this one time we went out, we received 21 children that were eligible for measles vaccination. 

“We had 10 children that were eligible for the second dose, and 11 for first dose. We managed to vaccinate 20 children without any challenges using two vials, but there was one child who remained who was supposed to get measles [dose] two. 

“We had to make that mother wait until we got more children to open the next vial – and we had no guarantee that we would get more children as the time the mother came was quite late in the day,” Mbewe recalls.

The child did not get immunised that day but Mbewe – who is also part of a team that follows up on children who are not vaccinated on time – advised the mother to visit the health centre on the dates that they conduct routine immunisations.

“The good part is that the mother managed to visit the facility, but now imagine a situation where the mother did not have the means to visit the health centre?” she asked. “Another thing is that this was not uncommon to happen – children would miss vaccines because we were scared of wastages. If you have one child at the opening of a five-dose vial, it’s possible to have three or even four children show up in the next six hours of the shelf life of that vial,” Mbewe added.

Replicable research?

Although the Zambia Ministry of Health began rolling out the five-dose MR vials at scale in 2023, the country had tried out the new presentation in select districts beginning in 2017. Those districts – and the experiences of health workers in them – became the focus of a study that ran until April 2018 and was published in 2020. 

“The effects of switching from ten to five-dose vials of MR vaccine on vaccination coverage and wastage: A mixed-method study in Zambia” brought together researchers from John Snow Inc. (JSI) and the Ministry of Health Zambia’s Immunisation Program.

The study team zeroed in on two provinces – Luapula and Central Provinces – where they tested the effects of the vial switch on coverage, drop-outs, wastage, session size and frequency, and on health worker behaviour.

While the study’s authors noted that the national guidance was clear that health workers should open a vial for every eligible child, it became clear that health workers often chose to prioritise waste reduction, with interviewees informing the researchers that they would wait, on average, for five children be present for vaccination before they opened a ten-dose vial. 

The arrival of the five-dose vials permitted that decision threshold to drop meaningfully, the researchers saw, with surveyed health workers noting they were willing to open a five-dose vial for just a single child.

Open-vial wastage also fell by as much as 47% in those clinics which had switched to the five-dose format, as compared to those facilities still using the ten-dose vials.

And coverage climbed, in what researchers described as a “noteworthy research finding”. Rates of vaccination with the first dose of the MR vaccine climbed 4.9% in the study area; coverage with the second dose rose 3.5%.  

Will the pilot’s gains echo out across Zambia, now the vial switch has become general? The data to prove it is not yet available, according to Ministry of Health officials. However, my conversations with health workers left me optimistic.