Mass Vaccination Campaigns Can Reduce Yellow Fever Outbreaks

In a recent paper, researchers were able to quantify preventive mass vaccination campaigns (PMVC) to reduce yellow fever outbreaks at the province level using the self-controlled case series (SCCS) method.

During this study period, an estimated 22% to 45% of outbreaks were averted by PMVCs in Africa.

Moreover, this study published by PLOS on February 18, 2021, observed a puzzling U-shaped association between vaccination coverage and the risk of an outbreak in the cohort analysis. 

This study offers new empirical evidence of the high preventive impact of PMVCs on yellow fever outbreaks. This study illustrates that the SCCS method can be advantageously applied at the population level to evaluate a public health intervention.

Moreover, these results may encourage the rapid rescheduling of yellow fever PMVCs postponed due to the COVID-19 pandemic.

To their knowledge, this is the first time an SCCS analysis was conducted at the population level.

The Eliminate Yellow fever Epidemics (EYE) strategy was launched in 2017 by the World Health Organization (WHO) in response to the resurgence of yellow fever in Africa and the Americas.

The threat of yellow fever outbreaks continues to affect countries in Africa and the Americas. The unprecedented urban outbreaks in 2016 demonstrated that despite the advances in immunization activities, challenges remain in ending yellow fever epidemics.

The EYE Strategy objectives address these challenges and rely on several vaccination activities, including PMVCs.

Yellow fever is a mosquito-borne, vaccine-preventable disease that may cause large urban outbreaks, especially in tropical African regions.

The WHO says ‘immunization is considered to be the most important and effective measure against yellow fever. A single dose of yellow fever vaccine is sufficient to provide life-long immunity and protection against the disease.’

Safe and effective yellow fever vaccines have been available for more than 80 years, says the U.S. CDC. The yellow fever vaccine is a live, weakened form of the virus.

Stamaril Vaccine: Stamaril is a live, attenuated yellow fever vaccine that contains the active substance Yellow fever virus 17D-204 strain produced in specified pathogen-free chick embryos.  It is given as a single subcutaneous (or intramuscular) injection.

Stamaril has been offered in Europe and other countries for decades. It is currently distributed in over 70 countries and is available in the USA during 2020 and 2021. 

However, Stamaril is considered investigational in the USA, as it is not a U.S.-licensed product.

Vax-Before-Travel publishes research-based travel vaccine news.