Measles - South Sudan - Prevention is better than cure

Spread the Message

Read Time:9 Minute, 31 Second

Children brought in to receive the measles-rubella (MR) vaccine at an immunization centre in Kalanki, Kathmandu.

10 February 2023

Situation at a glance

Since January 2022 to 1 February 2023, health authorities in South Sudan are responding to an ongoing outbreak of measles, with 4339 suspected cases including 388 (8.9%) laboratory-confirmed cases and 46 deaths (case fatality ratio: 1.06%) reported across the country. Two outbreaks of measles were declared by the health authorities in 2022 on 23 February and 10 December, respectively. Between March and November 2022, a total of 770,581 children were vaccinated during reactive vaccination campaigns. A nationwide vaccination campaign against measles is planned to begin in March 2023.

The current outbreak may have serious public health impacts due to the low national level of measles immunization coverage which is below the expected 95% coverage to interrupt the ongoing transmission. Other factors include the most affected age group being those under five years old, and the country context where there are armed conflicts, food insecurity and internally displaced people favoring transmission.

Description of the situation

Health authorities in South Sudan have been responding to an outbreak of measles since the beginning of 2022. From 1 January 2022 to 1 February 2023, a total of 4339 suspected cases, of which 388 (8.9%) were laboratory-confirmed cases and 46 deaths (CFR: 1.06%; AR: 1.1/1000 population) have been reported from 55 counties in all of the 10 states and three administrative areas. Of the 4339 suspected cases, 3187 (73.5%) are unvaccinated. Among the unvaccinated, 2398 (75%) are under the age of five and 1021 (32%) are under the age of one. The highest cumulative number of deaths was recorded in Juba county in Central Equatoria state with 18 deaths (CFR 1.9%) and eight deaths (CFR 5.1%) reported in Cueibet county of Lakes state, while other counties reported less than five deaths in total.

South Sudan started reporting measles cases in January 2022 in two counties -Torit in Eastern Equatoria State and Maban in Upper Nile State. Following a steady increase in the number of cases across the country, South Sudan’s health authorities declared a measles outbreak on 10 December 2022. This was the country’s second declaration of a measles outbreak after the first declaration on 23 February 2022.

Figure 1: Distribution of suspected measles cases (n=4334) reported in South Sudan between 1 January 2022 and 1 February 2023 .

Note: date of onset of disease was not known for five cases

Epidemiology of measles

Measles is a highly contagious disease caused by the measles virus and occurs as a seasonal disease in endemic areas. In tropical zones, most cases of measles occur during the dry season, whereas in temperate zones, incidence peaks during late winter and early spring.

Transmission is primarily person-to-person by airborne respiratory droplets that disperse within minutes when an infected person coughs or sneezes, and transmission can also occur through direct contact with infected secretions. Transmission from asymptomatic exposed immune persons has not been demonstrated. The virus remains active and contagious in the air or on infected surfaces for up to 2 hours. A patient is infectious four days before the start of the rash to four days after the appearance of the rash. The virus first infects the respiratory tract before spreading to other organs. There is no specific antiviral treatment for measles and most people recover within 2-3 weeks.

Among malnourished children and immunocompromised people, including people with HIV, cancer and treated with immunosuppressives, as well as pregnant women, measles can also cause serious complications, including blindness, encephalitis, severe diarrhea, ear infection, and pneumonia

Although measles is highly contagious, an effective and safe vaccine is available for prevention and control. The measles-containing vaccine first dose (MCV1) is given at the age of nine months, while the booster dose measles-containing second dose (MCV2) is given at the age of 15 months. A 95% population coverage of MCV1 and MCV2 is required to stop measles circulation.

In countries with low administrative vaccination coverage, epidemics typically occur every two to three years and usually last between two and three months, although their duration varies according to population size, crowding, and the population’s immunity status.

Public health response

With support from WHO and partners, the Ministry of Health of South Sudan, has implemented response measures including enhancing measles surveillance and strengthening case management by reinforcing capacities of frontline healthcare workers, surveillance officers, and the state and county rapid response teams (RRT). In addition, response interventions include:

Strengthening coordination through activated Public Health Emergency Operation Centers (PHEOC), adoption of measles into the National Steering Committee (for COVID-19 response and Ebola Virus Disease preparedness) and other weekly coordination platforms.
Enhancing surveillance including deployment of RRTs for investigation and sampling of suspected cases.
Weekly analytics and monitoring of disease trends in affected locations.
Between March and November 2022, reactive vaccination campaigns were conducted in 16 of the 23 counties with confirmed outbreaks where 770 581 children were vaccinated.
A nationwide non-selective measles vaccination campaign, where children irrespective of their vaccination status are eligible for vaccination, is planned to begin in March 2023.
Enhancing case management of symptomatic cases through supportive management and vitamin A supplementation.
Strengthening community engagement and mobilization to increase awareness and demand for vaccine and encourage health-seeking behaviors.
Using WHO measles programmatic risk assessment tool, a risk analysis, was conducted in March 2022. The tool identifies areas where measles programmatic activities need to be strengthened to reach elimination and reduce outbreak risk countrywide.

WHO risk assessment

In South Sudan, outbreaks of measles remain a concern due to insufficient vaccination coverage, the non-introduction of the second dose of MCV (MCV2) and the absence of supplementary vaccination activities against measles in some areas over the past three years.

South Sudan is one of the African countries with the lowest measles immunization coverage, resulting in suboptimal population immunity. The 2020 WHO-UNICEF estimates of National Immunization Coverage (WUENIC) for the first dose of measles containing vaccine (MCV1) were estimated to be 49%.

Based on the measles risk analysis conducted in March 2022, 49 counties out of 80 (69%) in 10 states and three administrative areas are classified as “very high risk” for measles transmission. All states and three administrative areas, except for the Western Equatoria, are classified as “very high risk”. The assessment found that out of 80 counties, eight (10%) have a low risk of measles and 12(15%) are classified as ‘medium’ risk when assessing population immunity. The remaining 60 counties (75%) are classified as either “high risk” or “very high risk” for measles. This risk analysis looked at several factors including population immunity, surveillance quality, immunization programme, and threat assessment (factors that might influence the risk for measles virus exposure and transmission in the population).

Although most counties recorded very high administrative coverage for immunization for measles during reactive campaigns conducted between March and November 2022, vaccination quality was not determined by a post-campaign evaluation (PCE).

Low routine immunization coverage (69%), far below the WHO recommended sustained homogeneous coverage of at least 95%, is the main underlying cause of the multiple outbreaks in South Sudan. The low routine immunization is attributed to several factors including low access to basic healthcare estimated at 44%; insecurity that affects the functioning of health facilities; and inconsistent implementation of the basic package for nutrition and health services by public and partner-supported health facilities.

South Sudan is also experiencing severe food insecurity with 57% of the population (6.54 million people) being affected. This has increased the risk of malnutrition in children, thereby increasing the risk of severe measles and adverse outcomes, especially those with vitamin A deficiency or whose immune systems have been weakened by HIV or other chronic diseases.

Due to these multiple factors outlined above, the risk of spread of measles at the national level is assessed as high. At regional level, the risk is assessed to be moderate due to the cross-border movement of populations fleeing armed conflicts and insecurity in neighboring countries (Ethiopia, Sudan, Uganda, the Democratic Republic of the Congo, and Kenya) with suboptimal coverage of routine vaccination.

The risk at the global level is considered as low given the existing response capacity in place.

WHO advice

Vaccination against measles is recommended for all susceptible children and adults. Reaching all children with two doses of measles vaccine should be the standard for all national immunization programs. Countries aiming at measles elimination should achieve ≥95% coverage with both doses equitably to all children in every district. Routine vaccination of children against measles, combined with mass immunization campaigns in countries with high morbidity and mortality rates, are key public health strategies to reduce global measles deaths. Two doses of the vaccine are recommended to ensure immunity and prevent outbreaks, as about 15% of vaccinated children fail to develop immunity from the first dose.

There is no specific treatment for measles. Case management of measles focuses on supportive care as well as the prevention and treatment of measles complications and secondary infections. Since measles is highly contagious, patient isolation is an important intervention to prevent further spread of the virus.

Supportive care includes relieving common symptoms such as fever, cough, nasal congestion or rhinorrhea, conjunctivitis, and sore mouth. Nutritional support is recommended to reduce the risk of malnutrition due to diarrhea, vomiting and poor appetite associated with measles. Breastfeeding should be encouraged where appropriate. Oral rehydration salts should be used as needed to prevent dehydration.

All children diagnosed with measles should receive two doses of vitamin A oral supplements, given 24 hours apart, irrespective of the timing of previous doses of vitamin A; 50 000 IU should be given to infants aged less than six months, 100 000 IU to infants aged 6–11 months, and 200 000 IU to children aged ≥12 months. This treatment restores low vitamin A levels in acute measles cases that occur even in well-nourished children and can help prevent eye damage and blindness. Vitamin A supplements have also been shown to reduce the number of measles deaths.

In unimmunized or insufficiently immunized individuals, measles vaccine may be administered within 72 hours of exposure to measles virus to protect against disease. If disease does develop, symptoms are usually not severe, and the duration of illness is shortened.

Healthcare workers should be vaccinated in order to avoid infections acquired in a healthcare setting.

WHO does not recommend any travel and/or trade restrictions to South Sudan based on the information available for this event.