Millions of children around the world missed out on key vaccinations during the Covid-19 pandemic, according to a new analysis by UNICEF and the World Health Organization (WHO). One health official called it "the largest sustained drop in childhood immunization in a generation."

How vaccination campaigns for kids worked in the past–and why they’re so hard to make effective today.

Childhood vaccinations sharply dropped during the pandemic

According to new data released Thursday by UNICEF and WHO, the average global childhood immunization rate for 11 diseases dropped from 71% in 2019 to 68% in 2021—the first time the rate has decreased in over 30 years.

This decline in immunization was worse for certain vaccination programs. For example, coverage for all three doses of the diphtheria, tetanus, and pertussis (DTP) vaccine, which is often used as a benchmark for immunization coverage, dropped five percentage points between 2019 and 2021 to 81%. Overall, the number of children not vaccinated against DTP rose to 25 million in 2021, with 18 million of those children being from low- and middle-income countries, including Ethiopia, India, Indonesia, Nigeria, and the Philippines.

Similarly, vaccination rates for measles and polio also declined during the pandemic. In 2021, measles vaccination rates fell to 81%, the lowest they've been since 2008, and polio vaccination rates dropped to 80%.

Although many childhood immunization experts hoped that declines in vaccination coverage in 2020 due to pandemic lockdowns and overburdened health systems would recover in 2021, they only got worse. According to Niklas Danielsson, a senior immunization specialist with UNICEF who is based in Nairobi, misinformation about Covid-19 vaccines and a broader mistrust of governments' public health measures likely contributed to these declines in routine childhood immunizations.

"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, executive director of UNICEF. "Covid-19 is not an excuse" for vaccination rates dropping.

Can childhood vaccination rates get back on track?

According to the Washington Post, some health experts are hopeful that childhood vaccination rates can rebound after the steep declines over the past few years. In fact, some countries, including Uganda and Pakistan, were able to maintain high vaccination rates even during the pandemic.

"Planning and tackling Covid-19 should also go hand-in-hand with vaccinating for killer diseases like measles, pneumonia, and diarrhea," said WHO Director-General Tedros Adhanom Ghebreyesus. "It's not a question of either/or, it's possible to do both."

Similarly, Jennifer Requejo, UNICEF's lead for global health data, said that while current trends are alarming, global vaccination rates have previously been able to improve after periods of stagnation. "There are things that can be done," Requejo said. "We know that it's possible through political commitment [and] through greater resources."

However, Lily Caprani, UNICEF's head of advocacy, said that an enormous amount of resources and effort would be needed to bring immunization rates back to pre-pandemic levels.

"It's not going to be enough to just go back to business as usual and restore ordinary, routine immunization," she said. "We're going to need really concerted investment and catch-up campaigns, because there's a growing cohort of millions of children who are completely unimmunized living in countries that have high levels of malnutrition and other stresses."

Caprani underscored the necessity of training and deploying thousands more community health workers to help combat the current childhood immunization crisis, which has largely gone overlooked in favor of other global public health initiatives.

"We aren't going to solve this with poster campaigns or social media posts," Caprani said. "You need outreach by reliable, well-trained, properly compensated community health workers who are out there day in, day out, building trust — the kind of trust that means you listen to them about vaccines. And there simply aren’t enough of them." (Nolen, New York Times, 7/15; Taylor, Washington Post, 7/14; WHO/UNICEF press release, 7/15)