The COVID-19 Vaccination Challenge: Lessons From History

The COVID-19 pandemic has highlighted the challenges of not only developing vaccines, but also making sure everyone who should get them does. Though more than a dozen COVID-19 vaccines are now being distributed around the world, vaccination campaigns face many hurdles: limited availability, public mistrust, and dosage and storage requirements can all jeopardize vaccination coverage. A look at previous vaccine distribution efforts showcases some of the main challenges.

How do rates for routine vaccines stack up?

Public health experts worldwide consider vaccines to be among medicine’s most important achievements, helping to reduce the prevalence of some diseases, such as polio, to near zero. Yet, even for diseases with vaccines, achieving and maintaining high coverage can be difficult. The World Health Organization (WHO) has warned of a “dangerous stagnation” of vaccination rates in recent years.

There are many factors that affect a vaccine’s coverage rate. These include:

Availability. Countries can face vaccine shortages for a range of reasons, including conflict and insufficient production capacity. The WHO has noted a global shortage [PDF] of the human papillomavirus (HPV) vaccine in recent years due to limited manufacturing capacity amid rising demand. In the case of the COVID-19 crisis, production capacity is being tested on an unprecedented scale. Amid a devastating outbreak in India in mid-2021, the Serum Institute of India—the world’s largest vaccine manufacturer—announced it would not be able to meet its commitments to deliver doses to other low-income countries.

Distribution also presents a hurdle, particularly for rural or remote areas. Some vaccines, such as that for chickenpox (varicella), must be kept at very low temperatures when transported and stored, a process known as the cold chain. Similarly, the Pfizer-BioNTech COVID-19 vaccine initially required storage in ultra-cold freezers; however, following the release of new data, it can now be kept in standard refrigerators for up to one month, making the vaccine more accessible.

Public understanding and trust. Health officials can build trust in their communities through clear and transparent communication about vaccines. This includes information about their effectiveness, any expected side effects, and when to return for booster shots. Experts have raised alarm about increasing vaccine skepticism, which has led to measles outbreaks in a number of countries. Mistrust similarly undermined efforts to fight Ebola outbreaks in the Democratic Republic of Congo. There is also mounting concern about what health officials have termed an “infodemic” of misinformation and campaigns to deliberately spread false information about COVID-19 vaccine effects. Hesitancy about COVID-19 vaccines remains high in the United States, with nearly 30 percent of Americans surveyed saying they will not get vaccinated or are unsure about getting vaccinated, according to a July 2021 poll by the Economist and YouGov.

Complexity of the vaccine series. Sometimes two or more doses are recommended for maximum protection, with weeks or even months between doses. The Moderna and Pfizer-BioNTech vaccines both require two doses, and individuals are required to receive the same vaccine for both doses.

Recommendations. Health authorities often designate a vaccine for particular age groups or for people that share certain health risks. In the United States and some other countries, visits to the pediatrician are largely determined by vaccination schedules, making it much easier to achieve high coverage among infants and toddlers. Teens and adults typically don’t make routine doctor visits, lowering their coverage. Ahead of the COVID-19 vaccine rollout, health agencies in many countries issued guidance for phased vaccination campaigns, with health-care workers and residents of nursing homes and long-term care facilities first in line.

How do these variables affect coverage globally?

Recommendations for a particular vaccination can vary significantly across countries. For example, in the United States, an annual flu vaccine is recommended for anyone six months or older, while in some European countries, such as Belgium and Lithuania, it is only recommended for high-risk groups, which include health-care workers, pregnant women, and people with weakened immune systems. As a result, coverage rates can look very different around the globe.

The WHO’s Europe office has expressed concern about the declining use of influenza vaccines across the region, citing limited procurement of vaccines, health-care providers not advising the vaccination, out-of-pocket costs, and low public confidence.

How is the pandemic affecting vaccination coverage?

Amid the pandemic, a major concern among health experts has been drops in coverage for routine vaccinations, as some families avoided visits to health-care facilities and resources and personnel were diverted to focus on the COVID-19 crisis. In 2020, twenty-three million children globally missed basic vaccinations, according to the WHO and the UN Children’s Fund (UNICEF).

Health officials likewise urged citizens to get their flu shot to avoid a “twindemic” of seasonal influenza and COVID-19. Yet, in the United States, Europe, and elsewhere, the number of flu cases appeared unusually low, with health experts mainly crediting social distancing and other pandemic-related measures.

Where do COVID-19 vaccination rates stand?

Even in the best of times, effective vaccination policy involves many moving parts. Despite the successful development of COVID-19 vaccines, just 14 percent of the world’s population is fully vaccinated against the disease and less than 30 percent has received at least one dose. In Africa, the share of fully vaccinated is dramatically lower, at under 2 percent.

The sluggish global rollout has raised alarm as new, more infectious variants of the coronavirus have emerged. Now, officials are implementing or considering vaccination mandates to keep their countries trending in the right direction. For instance, Indonesia mandated in February that all eligible citizens be vaccinated, threatening fines or suspended social services for those who refuse. Starting in August, Saudi citizens will be required to show proof of vaccination to enter many public and private spaces. France and Greece are requiring all health-care workers to be vaccinated by September. A growing number of U.S. public-sector organizations are also mandating vaccination.

Will Merrow and Zachary Rosenthal created the graphics for this In Brief.