A health worker holds up a dose of a vaccine in front of a group of young children

Catch-up immunization drives are needed in many countries around the world.Credit: Hussain Ali/Anadolu Agency/Getty

Last month, the United Nations children’s agency UNICEF and the World Health Organization sounded a troubling distress call. Because of disruptions to planned immunization campaigns, 125 million children around the world are waiting for essential vaccinations against diseases such as measles; diphtheria, tetanus and whooping cough (DTP); and polio. It is the “largest sustained drop in childhood immunization in a generation”, the organizations say.

The COVID-19 pandemic and its effects are the main reason immunization campaigns have been disrupted. Lockdowns, interruptions to supply chains and the diversion of community health workers to focus on treating people with COVID-19 have all contributed. Ongoing civil and political conflicts around the world have also played a part.

Before the pandemic, childhood-vaccination programmes were among the better-functioning elements of global public health. Between 2011 and 2019, about 85% of children received minimum coverage (three doses of DTP and one of measles). This figure was short of a global target of 90%, but it was, nevertheless, relatively stable for around a decade. That stability has been shattered, with the figure for 2021 standing at 81%.

To get immunization programmes back on track, concerted catch-up campaigns will be needed. Although some countries have been able to get back up to speed with vaccinations, 26 nations are yet to restart campaigns that were paused because of COVID-19, including large middle-income countries such as India and Indonesia.

Rising risk of disease

More than anything, governments must get organized and treat childhood immunization as an urgent priority. If they don’t, there’s a risk that the prevalence of vaccine-preventable diseases will increase. This year has already seen a surge in measles cases, with more than 40,000 reported in the first quarter, many of them in Afghanistan, Ethiopia and Yemen. This is more than double the 16,500 cases recorded in the first quarter of 2021. And cases of wild polio virus have been reported in Malawi and Mozambique, their first in almost 30 years.

International donors also need to get their act together and work with governments to get things moving. Often the greatest demand is for trained community health workers. These include vaccinators, but also people trained in science and medical communication who can assist in cases in which people are hesitant about vaccines. UNICEF says that some local health authorities also need help identifying and recording households where vaccinations have been missed, a role that could be filled by students and researchers. There’s also scope for more sharing of knowledge and best practice — international organizations could, for example, facilitate exchanges between those countries that have been able to catch up and those that are yet to do so.

Nations that have succeeded in getting back on track include Bangladesh, which was able to return vaccination rates to pre-pandemic levels thanks to joined-up action all the way from the prime minister’s office to local health authorities. Thousands of extra health-care workers were trained in how to administer vaccines, and the country also deployed real-time digital tools to allow health-care workers to upload and monitor data on vaccine coverage.

Other countries have been able to reach pre-pandemic immunization targets by bundling together COVID-19 vaccination campaigns and non-COVID-19 childhood immunization and other health and education services. According to UNICEF, authorities in the Central African Republic combined COVID-19 vaccinations with polio, vitamin A and deworming campaigns. Iraq deployed mobile vaccination teams. In Ethiopia, women are being screened for COVID-19-vaccination status when they come into health-care centres for ante- and postnatal care, and are offered a vaccine. In some of Mali’s rural regions, where catch-up campaigns are difficult to implement because of civil and political conflict, vaccinations for children are also being offered alongside routine health services, such as primary care.

Children from some of the poorest countries and households, those in places with the weakest public-health systems and those in regions involved in conflict have been set back the most. But this setback can be remedied. “Quite simply, we have the tools we need at our disposal — including proven vaccines — we just need to get them into the communities that need them,” UNICEF’s head of advocacy for child health and survival, Lily Caprani, told Nature. We completely agree.