Tanzania’s “big catch-up” gains ground

In the global effort to get immunisation back on track post-pandemic, the east African nation has emerged as a frontrunner.

  • 1 May 2024
  • 6 min read
  • by Syriacus Buguzi ,   Gavi Staff
The World Health Organization staff interacting with a parent who had taken her son for vaccination in Babati, Tanzania. Credit: WHO Country Office-Tanzania
The World Health Organization staff interacting with a parent who had taken her son for vaccination in Babati, Tanzania. Credit: WHO Country Office-Tanzania


Saumu Ramadhani, a Community Health Worker (CHW) in Kwa Mtoro, a village in central Tanzania, witnessed the backsliding of immunisation efforts as COVID-19 swept the globe, sparking panic.

Some families skipped routine clinic visits, in fear that they could catch the pandemic virus in hospital settings, Ramadhani said. And, as interest in the race to create a vaccine against the deadly new pathogen swelled, so did anti-vaccine misinformation.

According to Tanzania’s Ministry of Health, the country had reached 54% of children identified as “zero-dose” with DTP1 by December 2023, and had fleshed out an ambitious plan to reach the remainder by end 2024.

Around the world, millions more children missed out on one or more routine immunisations in 2020, 2021 and 2022 than had done so in 2019, WHO and UNICEF confirmed. In 2019, 86% of Tanzanian children were vaccinated with the third dose of the basic diphtheria, pertussis and tetanus-containing vaccine (DTP3), which serves as a conventional yardstick for immunisation coverage in general. By 2021, that had dropped to 81%, rising to 84% in 2022.

“Even before the pandemic, I saw many parents who skipped taking their children for routine immunisation,” said Ramadhani. There were many reasons for that – some families in Chemba District reside 15 kilometres away from the nearest town centre, with no easy access by road. In some cases, they are cut off by a river, or lack the means to fund transportation. Other locals harbour deep-seated anxieties about vaccines.

“When COVID came, it was like adding fuel to the fire,” Ramadhani explained.

Enter the fire brigade. In late 2022, Tanzanian health leaders designed a large, ambitious routine immunisation catch-up strategy. In January 2023, the wheels began to turn: unvaccinated ‘zero-dose’ children would be located and reached with life-saving vaccines. 

According to Jonna Jeurlink, who leads Gavi’s Tanzania team, that made the east African nation something of a “pathfinder”: the launch of the catch-up effort there pre-empted, by a full three months, the April kick-off of a Gavi, UNICEF and WHO-led global initiative branded “The Big Catch-Up”.

“That meant Tanzania was able to offer lessons for the many other countries struggling with a similar decline in routine immunisation,” Jeurlink emphasised.

How it’s done: Catching up Tanzania

The burning problem in Tanzania, as in pretty much every other country post-pandemic, was the build-up of a cohort of kids who were unprotected by basic vaccines. That means that Tanzania’s strategy centres on identifying and vaccinating all 'zero-dose' and under-immunised children – those, in conventional terms, who have not received even the first dose of the basic diphtheria, tetanus and pertussis-containing vaccine (DTP1).

How? The key mechanism at work is the quarterly ‘PIRI’: periodic intensified routine immunisation outreach efforts. These are mini-campaigns, delivered in targeted low-coverage – and therefore high-risk – zones.

Not all PIRIs are created equal. Being small, and targeted, PIRIs are very specific to context: tactically very different if they are providing services to a peri-urban community, than if they are catching up an island population, for instance.

And, while coverage with the DTP jab is the conventional indicator for vaccination gaps, Tanzania’s catch-up casts its net wider, including efforts to patch up gaps in measles-rubella (MR), human papillomavirus (HPV) and rotavirus vaccine coverage.

Big strides

A year and three months later, Tanzania’s catch-up strategy has made big strides – outpacing many of its neighbour countries. According to Tanzania’s Ministry of Health, the country had reached 54% of children identified as zero-dose with DTP1 by December 2023, and had fleshed out an ambitious plan to reach the remainder by end 2024.

Dismas Damian, a field epidemiologist with the Global Polio Eradication Initiative (GPEI) has provided technical support to immunisation programs in Tanzania. He tells VaccinesWork that the success of the catch-up strategy so far has hinged on an integrated approach, meaning that rather than focusing on a single antigen at a time, the campaign has made several routine vaccines available at contact points.

That, in turn, has relied on solid intelligence gathering – known as microplanning – conducted by local health workers. Damian says that mobile outreach teams, as well as community health workers and community leaders, were key in finding children who had so far missed out on all their vaccines. The teams identified areas with low vaccination rates, as well as unvaccinated individual children, by going – literally – the extra mile: assessing the situation on-site, interviewing parents and analysing data.

“This allowed the teams to plan targeted outreach efforts for maximum impact,” Damian says.

Pre-pandemic systems ground nimble response

Dr Florian Tinuga, the national Program Manager for the Immunization and Vaccine Development (IVD) programme at the Ministry of Health echoes him, saying the strides made by Tanzania in getting zero-dose children protected stemmed from the proactive identification of the children.

And while the catch-up was necessitated by aberrant circumstances, the mechanisms it relied were well-established in the health system pre-pandemic. “We had already established systems for finding children who missed routine vaccinations, via defaulter tracing and micro-planning, and reaching them through [PIRIs],” he explains.

“Through our immunisation programme, we had defined the at-risk group before COVID-19. We were able to effectively target this group after the pandemic and quickly address the growing number of unvaccinated children.”

Outbreaks flare – then subside

Still, there’s no downplaying the disruption the pandemic brought with it. This disruption, Tinuga says, “led to increasing number of unvaccinated children and decreasing herd immunity.” He points to the large-scale measles outbreaks in Tanzania in recent years as evidence of diminished collective protection.

“Without intensifying the catch-up efforts, we would not have been able to deal with the outbreaks,’’ says Tinuga, highlighting that the lessons learned from this campaign will be invaluable for in the country’s future vaccination campaigns. They’ll also provide a blueprint for other countries facing similar challenges.

Next phase

With more than half of missed-out children already reached in 2023, 2024 will see phases III and IV of the “catch-up” strategy kick off – with the aim of reaching every last child. Tinuga says Tanzania demand-generation activities are ongoing, and integrated PIRIs that will provide DTP1, rotavirus and HPV vaccination are in the works. Efforts to extend protection against measles and rubella are also in progress.

Dr Ntuli Kapologwe, Director of Preventive Services at Tanzania’s Ministry of Health, credits Tanzania’s success in part to financial support from Gavi, which has been critical to mobilising personnel, supplies and outreach initiatives.

Gavi contributed US$ 5.8 million to fund Tanzania’s catch-up plan in 2023. The organisation also rerouted an additional 10 billion Tanzanian shillings (about US$ 3.7million) that had originally been earmarked for the COVID-19 response, to support immunisation catch-up efforts for 2024.

“With these collaborative efforts, we have been able to reduce transmissions of vaccine-preventable diseases and hence stop outbreaks caused by disrupted immunity,” says Kapologwe.