So far, measles has been eliminated in 81 countries and rubella in 93. But factors such as antivaccination sentiment and misinformation linking vaccination to autism have led to occasional outbreaks. In addition, because the COVID-19 pandemic fueled lower routine vaccination coverage and postponed public health campaigns, some countries have also lost previously gained ground.
The study, which is slated for publication in the October 1 issue, explored the likelihood of eliminating measles and rubella, based on vaccination strategies in 93 countries with the highest measles and rubella burden, under two vaccination scenarios: 1) a “business as usual” approach, ie, continuing current vaccination coverage via routine childhood immunization schedules, and intermittent vaccination campaigns that target age groups to vaccinate quickly (known as SIAs); and 2) an “intensified investment approach” that scales up SIA vaccination coverage into the future.
Both vaccination scenarios were evaluated within the context of two national models (Johns Hopkins University and Public Health England), and one subnational model (Nigeria) for rubella transmission.
Lead author Amy Winter, PhD, assistant professor of epidemiology and biostatistics, University of Georgia College of Public Health, Athens, told Medscape Medical News that “under the intensified investment scenario, rubella elimination is likely to be achieved in all 93 countries that were modeled [but] measles elimination is likely in some but not all countries.”
This is especially the case if the goal is cessation of vaccination campaigns, study authors noted when placing the research in context.
But Winter also emphasized that Nigeria offered specific lessons not seen in the national models.
For one, “when you’re conducting a vaccination campaign it’s essential to be hitting kids who haven’t already had a routine vaccine.”
In addition, she stressed a need to improve vaccine equity by focusing on areas with really low coverage and then moving into areas with higher coverage.
“The Nigerian subnational analysis definitely illustrates the importance of achieving equitable vaccination and the need for potentially targeted strategies to improve vaccination,” she said. “The initial focus should be on getting areas with low coverage up to par.”
Still, “even with the intensified investment approach, we won’t be able to eradicate measles,” William Moss, MD, professor of epidemiology and executive director, International Vaccine Access Center, Johns Hopkins University, Baltimore, Maryland (who was not directly involved in the study), told Medscape Medical News.
Pandemic Interruptions, Future Strategies
In a related editorial, the authors noted that COVID-19 has markedly disrupted vaccination campaigns globally.
In 2017, 118 (61%) countries achieved the Global Vaccine Action Plan 2020 target of ≥ 90% national MCV1 (first dose of measles vaccine) coverage. Since that time, measles coverage has declined from 84%-85% in 2017 to 81% in 2021, leaving 24.7 million completely unprotected (also known as zero-dose children) and 14.7 million children underimmunized (ie, recipients of only 1 dose).
Notably, this is the lowest immunization level since 2008, with more than 5 million more children missing their first measles dose.
Moss has previously written on the biological feasibility of measles eradication and told Medscape that it’s not tenable to rely on increased vaccination coverage alone.
We need “new tools and the new strategies. One of the ones that we’re most excited about [is] microarray patches,” he said, noting that they are thermostable and can be administered by anyone.
Moss also said that, while he is hoping for point-of-care rapid diagnostics, the focus of the efforts needs to change.
“Where’s [the] measles virus coming from? Where’s it being exported from and where is it being imported to?” he posited, adding that the focus should be on these areas “to try to shut down transmission…a radical kind of second phase of a measles eradication puts aside equity and focuses on sources and sinks.”
In the interim, rubella elimination looks promising.
“It’s not as contagious (as measles) and has a lower sort of herd immunity threshold because of it,” Winter said.
Winter and Moss report no relevant financial relationships. The study was funded by WHO, Gavi, the Vaccine Alliance, the Centers for Disease Control and Prevention, and the Bill & Melinda Gates Foundation.