The largest sustained decline in childhood vaccinations in approximately 30 years has been recorded in official data published by WHO and UNICEF on Friday.

The percentage of children who received three doses of the vaccine against diphtheria, tetanus and pertussis (DTP3) – a marker for immunization coverage within and across countries – fell 5 percentage points between 2019 and 2021 to 81 per cent.  

As a result, 25 million children missed out on one or more doses of DTP through routine immunization services in 2021 alone.

This is 2 million more than those who missed out in 2020 and 6 million more than in 2019, highlighting the growing number of children at risk from devastating but preventable diseases.

The decline was due to many factors including an increased number of children living in conflict and fragile settings where immunization access is often challenging, increased misinformation and COVID-19 related issues such as service and supply chain disruptions, resource diversion to response efforts, and containment measures that limited immunization service access and availability.

“This is a red alert for child health. We are witnessing the largest sustained drop in childhood immunization in a generation. The consequences will be measured in lives,” said Catherine Russell, UNICEF Executive Director.

“While a pandemic hangover was expected last year as a result of COVID-19 disruptions and lockdowns, what we are seeing now is a continued decline. COVID-19 is not an excuse. We need immunization catch-ups for the missing millions or we will inevitably witness more outbreaks, more sick children and greater pressure on already strained health systems.”

Up to18 million of the 25 million children did not receive a single dose of DTP during the year, the vast majority of whom live in low- and middle-income countries, with India, Nigeria, Indonesia, Ethiopia and the Philippines recording the highest numbers.

Among countries with the largest relative increases in the number of children who did not receive a single vaccine between 2019 and 2021 are Myanmar and Mozambique.

Read: 25 million kids missed routine vaccinations because of COVID

Globally, over a quarter of the coverage of HPV vaccines that was achieved in 2019 has been lost.

This has grave consequences for the health of women and girls, as global coverage of the first dose of human papillomavirus (HPV) vaccine is only 15%, despite the first vaccines being licensed over 15 years ago.

It was hoped that 2021 would be a year of recovery during which strained immunization programmes would rebuild and the cohort of children missed in 2020 would be caught-up. Instead, DTP3 coverage was set back to its lowest level since 2008 which, along with declines in coverage for other basic vaccines, pushed the world off-track to meet global goals, including the immunization indicator for the Sustainable Development Goals.  

This historic backsliding in rates of immunization is happening against a backdrop of rapidly rising rates of severe acute malnutrition.

A malnourished child already has weakened immunity and missed vaccinations can mean common childhood illnesses quickly become lethal to them.

The convergence of a hunger crisis with a growing immunization gap threatens to create the conditions for a child survival crisis.  

Vaccine coverage dropped in every region, with the East Asia and Pacific region recording the steepest reversal in DTP3 coverage, falling nine percentage points in just two years.  

“Planning and tackling COVID-19 should also go hand-in-hand with vaccinating for killer diseases like measles, pneumonia and diarrhea,” said Dr Tedros Adhanom Ghebreyesus, WHO Director-General.

“It’s not a question of either/or, it’s possible to do both”.

Some countries notably held off declines. Uganda maintained high levels of coverage in routine immunization programmes, whilst rolling out a targeted COVID-19 vaccination programme to protect priority populations, including health workers.

Read: Children aged 5-12 to be vaccinated soon: Health Minister

Similarly, Pakistan returned to pre-pandemic levels of coverage thanks to high-level government commitment and significant catch-up immunization efforts.

To achieve this in the midst of a pandemic, when healthcare systems and health workers were under significant strain, should be applauded.  

Monumental efforts will be required to reach universal levels of coverage and to prevent outbreaks. Inadequate coverage levels have already resulted in avoidable outbreaks of measles and polio in the past 12 months, underscoring the vital role of immunization in keeping children, adolescents, adults, and societies healthy.  

First dose measles coverage dropped to 81 per cent in 2021, also the lowest level since 2008.

This meant 24.7 million children missed their first measles dose in 2021, 5.3 million more than in 2019.

A further 14.7 million did not receive their needed second dose.

Similarly, compared to 2019, 6.7 million more children missed the third dose of polio vaccine and 3.5 million missed the first dose of the HPV vaccine- which protects girls against cervical cancer later in life.  

The sharp two-year decline follows almost a decade of stalled progress, underscoring the need to not only address pandemic-related disruptions but also systemic immunization challenges to ensure every child and adolescent is reached.

WHO and UNICEF are working with Gavi, the Vaccine Alliance and other partners to deliver the global Immunization Agenda 2030 (IA2030), a strategy for all countries and relevant global partners to achieve set goals on preventing diseases through immunization and delivering vaccines to everyone, everywhere, at every age.

“It’s heart-breaking to see more children losing out on protection from preventable diseases for a second year in a row. The priority of the Alliance must be to help countries to maintain, restore and strengthen routine immunization alongside executing ambitious COVID-19 vaccination plans, not just through vaccines but also tailored structural support for the health systems that will administer them,” said Dr Seth Berkley, CEO of Gavi, the Vaccine Alliance.

The IA2030 partners call on governments and relevant actors to:

Intensify efforts for catch-up vaccination to address backsliding on routine immunization, and expand outreach services in underserved areas to reach missed children and implement campaigns to prevent outbreaks;

Implement evidence-based, people-centred, and tailored strategies to build trust in vaccines and immunization, counter misinformation and increase vaccine uptake particularly among vulnerable communities;

Ensure current pandemic preparedness and response and the global health architecture strengthening efforts lead to investment in primary health care (PHC) services, with explicit support to strengthen and sustain essential immunization;

Ensure political commitment from national governments and increase domestic resource allocation to strengthen and sustain immunization within PHC;

Prioritize health information and disease surveillance systems strengthening to provide the data and monitoring needed for programmes to have maximum impact; and  

Leverage and increase investment in research to develop and improve new and existing vaccines and immunization services that can achieve community needs and deliver on IA2030 goals.