Decline in Global Incidence of Congenital Rubella Syndrome Seen From 2010 to 2019

Between 2010 and 2019, the global incidence of congenital rubella syndrome (CRS) was reduced following the introduction of rubella-containing vaccination (RCV), according to results of a study published in the International Journal of Infectious Diseases. 

Researchers evaluated the impact of RCV on global CRS incidence in a systematic review. The researchers identified age-stratified data on rubella seroprevalence from previous research published from January 2012 to September 2020. Age-specific fertility rates, total number of live births from 1996 to 2019, and survival data were identified from participating countries via United Nations’ population databases. Countries in which RSV had been introduced were divided into World Health Organization (WHO) regions, and annual vaccination data were obtained from country-specific submissions. 

A total of 129 datasets from 70 countries were assessed to estimate the global CRS burden. Four catalytic models were used to evaluate seroprevalence data and calculate the mean age-specific prevaccination force of infection (ie, rate at which susceptible individuals are infected). The models were designed with the assumption that prevaccination force differed between individuals younger than 13 years and those 13 years and older. A transmission model was used to calculate the incidence of CRS per 100,000 live births and the annual number of infants born with CRS from 1996 to 2019. The transmission model also was designed to stratify populations by maternal immunity and by those who were susceptible, pre-infectious, infectious, and immune.

In 2019, the highest estimated regional CRS incidence per 100,000 live births was noted in the African region (64; 95% CI, 24-123), followed by the Eastern Mediterranean region (27; 95% CI, 4-76). Of note, the incidence of CRS in the African region decreased from 119 (95% CI, 62-209) to 64 (95% CI, 24-123) between 2012 and 2019.

Of 22 countries where RCV was not introduced by 2019, 17 were in in the African region (17% of global live births) and 5 were in the Eastern Mediterranean region (7% of global live births). Further analysis of the African region showed that South Africa had an estimated CRS incidence of 36 (95% CI, 2-93), whereas Nigeria had an estimated incidence of 130 (95% CI, <1-337). In the Eastern Mediterranean region, the estimated CRS incidence ranged from 50 (95% CI, <1-173) in Pakistan to 91 (95% CI, <1-202) in Sudan.

Low CRS incidence was observed in countries where RCV had been introduced. The estimated incidence of CRS was less than 1 in both the Western Pacific and Southeast Asian regions, as more than 95% of births had occurred following the introduction of RCV. 

The estimated global number of annual CRS diagnoses was 121,000 (95% CI, 70,000-191,000) in 2010. However, after the introduction of RCV, the estimated global number of annual CRS diagnoses decreased to 32,000 (95% CI, 13,000-60,000) by 2019, representing an overall reduction of 73% from 1996 to 2019. The highest estimated number of CRS diagnoses in 2019 were noted among Ethiopia, Republic of the Congo, Niger Pakistan, Nigeria, Uganda, and Sudan, with more than 1000 diagnoses annually.

Following the introduction of RCV, an estimated 229,000 (95% CI, 131,00-368,000) diagnoses of CRS have been averted. The highest number of averted CRS diagnoses was observed in the Southeast Asian region (125,000; 95% CI, 37,000-111,000).

Limitations of this study include the lack of seroprevalence data for certain countries, as well as the possibility that some datasets were not representative of surveyed populations. Moreover, the reduction in the transmission and incidence of CRS may have been overestimated.

According to the researchers, “With sustained coverage and the introduction of RCV into the remaining countries where it has not yet been introduced, further reductions are possible.”

This article originally appeared on Infectious Disease Advisor