UNIVERSITY PARK, Pa. — The World Health Organization, the United Nations agency responsible for global public health, recently recommended universal introduction of rubella vaccination, a major step towards potentially eradicating the disease. The change in global public health policy removes barriers that have kept countries, primarily in Africa, from introducing rubella vaccination and was influenced in part by research led by scientists at Penn State.

“Many people suspected that the existing policy was too restrictive and that it was propagating serious inequity because countries needed to prove that they could meet established benchmarks for vaccination coverage. The countries that were failing to meet the benchmark were the poorest countries, and it kept them from additional resources that could help them do so,” said Matt Ferrari, professor of biology and director of the Center for Infectious Disease Dynamics at the Huck Institutes of Life Sciences at Penn State. Ferrari was part of the team from the Measles and Rubella Partnership, a global partnership founded in 2001 and led by the American Red Cross, the Bill & Melinda Gates Foundation and others, that advocated for the policy change.

Rubella is a viral infectious disease that causes mild symptoms in children. However, among adults, there’s a potential risk for congenital rubella syndrome (CRS), a serious health condition that can occur if a pregnant person contracts the virus and passes it to her developing fetus, leading to birth defects and disability. According to the WHO, approximately 32,000 infants are born with CRS each year.

“When you introduce vaccination, you get a rapid decline in rubella disease and CRS because the amount of circulating virus in the population is reduced. Then, after a period of time where rubella is under control but not gone, the risk for CRS creeps up again. There’s a potential for that risk to exceed the pre-vaccination risk,” Ferrari said. That’s because the number of rubella infections in people of reproductive age — who were neither infected nor vaccinated as children — increases even as the total number of rubella cases goes down with vaccination.

WHO uses measles vaccination, which is implemented more widely, as a proxy for anticipating the coverage of a rubella-containing vaccine after a vaccination program is introduced. In 2000, WHO established a policy that required countries to demonstrate that they could immunize 80% or more of their population against measles before introducing a rubella vaccination program. Ferrari explained that when vaccination coverage is high, the lower risk of CRS due to less circulating rubella virus offsets the paradoxical increase in CRS risk because infections tend to happen later in life. To date, 19 countries have yet to introduce rubella vaccination. Six of these countries plan to introduce rubella vaccination in the near future while the remaining 13 countries haven’t met the recommended 80% benchmark for measles vaccination.

However, recent research provided more concrete estimates of the present-day burden of CRS, not just in the future. Ferrari and an international team led a recent study in Nigeria, analyzing data from a nationally representative serosurvey to determine how many people, particularly women of reproductive age, had rubella antibodies, an indicator that they already had the disease and were not at risk for CRS. The team used that data to estimate the CRS infection rate and the number of pregnancies at risk in the present day. They found that thousands of pregnancies are affected by CRS today whereas introducing vaccination would potentially lead to hundreds of cases in 10 to 15 years in the future.

“That really shifted the balance and got everyone to look at the cost we’re incurring today by not acting because we’re looking at the cost we might incur in the future if we act now,” Ferrari said.

The research in Nigeria, along with another study conducted in the Democratic Republic of Congo, led to a tipping point, Ferrari explained, and demonstrated that the 80% benchmark was too conservative.

“The evidence bubbled up and we said, now is the time to give this a shot,” Ferrari said. “We were able to resolve this question at a much finer level than before, anticipate the questions and provide evidence against it.”

Ferrari, along with members of the Measles and Rubella Partnership, presented the new evidence at the September meeting of the WHO Strategic Advisory Group of Experts on Immunization.

Based on the new evidence, WHO leaders agreed that the requirement was no longer warranted. WHO now recommends the universal introduction of rubella vaccination for the remaining countries that have yet to implement a vaccination program. WHO also recommended ongoing monitoring, follow-up campaigns and targeted interventions to prevent a paradoxical increase in CRS risk.

“[This project is] a great example of how modelers and policymakers and programmatic folks can work together,” said Natasha Crowcroft, senior technical adviser for measles and rubella at WHO.

With the policy barrier removed, countries can now begin to work toward securing funding and creating implementation plans for their rubella vaccination programs. That includes technical assistance on a regional and international level, Ferrari explained, to help countries develop high-quality proposals to Gavi, a global health partnership that partners with countries to implement vaccination programs, including providing financial assistance. It also involves investment in immunization infrastructure and bolstering the global vaccine supply chain.

Ferrari said that this is a major milestone not just for addressing rubella worldwide but for other infectious diseases, too. Since the rubella vaccine will be administered in conjunction with the measles vaccine, there will be a significant increase in population immunity for measles. According to Ferrari, the global health community has a chance to capitalize on an unprecedented opportunity to consider regional elimination or global eradication of measles or other infectious disease.

“I do research because I want to understand the world better, but science is only a piece of evidence-based policymaking,” Ferrari said. “The impact comes from everything you do after you get your results — leaning on long-term relationships with folks in the policy and operational community, understanding organizational priories and refining how you tell the story of your science. To impact policy, you have to be willing to let your science be one part of a larger narrative.”