Impact of rotavirus vaccine on rotavirus diarrhoea in countries of East and Southern Africa

Abstract

Background: Established in 2006 with four countries conducting hospital-based rotavirus surveillance, the African rotavirus surveillance network has expanded over subsequent years. By 2015, 14 countries in the World Health Organization (WHO) East and Southern Africa sub-region (Eritrea, Ethiopia, Kenya, Lesotho, Madagascar, Mauritius, Namibia, Rwanda, Seychelles, Swaziland, Tanzania, Uganda, Zambia and Zimbabwe) were participating in the rotavirus surveillance network coordinated by WHO. We monitored the proportion of rotavirus diarrhoea among children under five years of age who were hospitalized for diarrhoea in the sentinel hospitals from 2010 to 2015 among countries that introduced rotavirus vaccine during or before 2013 (Rwanda, Tanzania, Zambia and Ethiopia) and compared with the other countries in the network.

Methods: Children under the age of five years hospitalized due to acute diarrhoea were enrolled into the sentinel surveillance system and had stool samples collected and tested for rotavirus antigens by enzyme immunoassay. We described trends in rotavirus positivity among tested stool samples before and after rotavirus vaccine introduction.

Results: In countries that introduced rotavirus vaccine by 2013 (Rwanda, Tanzania, Zambia and Ethiopia), average rotavirus vaccine coverage from 2010 to 2015 improved from 0% in 2010 and 2011, 13% in 2012, 46% in 2013, 83% in 2014 to 90% in 2015. Annual average rotavirus positivity from 2010 to 2015 was 35%, 33%, 38%, 28%, 27%, and 19%, respectively. In countries that introduced rotavirus vaccine after 2013 or had not introduced by 2015, average rotavirus vaccine coverage was 0% in 2010-2013, 13% in 2014 and 51% in 2015. In these countries, rotavirus positivity was 44% in 2010, 32% in 2011, 33% in 2012, 41% in 2013, 40% in 2014 and 25% in 2015.

Conclusion: Countries that introduced rotavirus vaccine by 2013 had a lower proportion of rotavirus positive hospitalizations in 2013-2015 as compared to those that had not introduced rotavirus vaccine by 2013. The decrease in rotavirus positivity was inversely related to increase in rotavirus vaccine coverage showing impact of rotavirus vaccines.

Keywords: Diarrhoea; East and Southern Africa; Rotavirus; Vaccine impact.

Figure 1:

Diarrhoea hospitalizations and % Rotavirus Positive in East and Southern Africa countries 2010 – 2015

Figure 2:

Number of sentinel hospitals conducting rotavirus surveillance, 2010 – 2015, East and Southern Africa

Figure 3a:

Average rotavirus positives and rotavirus vaccine coverage for Rwanda, Tanzania, Ethiopia and Zambia 2010 – 2015

Figure 3b:

Average rotavirus positives and rotavirus vaccine coverage for Eritrea, Kenya, Lesotho, Madagascar, Mauritius, Namibia, Seychelles, Swaziland, Uganda and Zimbabwe 2010 – 2015

Figure 3c:

Trends in rotavirus positives versus time of rota-vaccine introduction in East and Southern African countries, 2010 – 2015 Rota vaccine by or before 2013: Rwanda (2012) and Tanzania, Ethiopia and Zambia by 2013. Rota vaccine by 2014: Eritrea, Kenya, Madagascar, Namibia and Zimbabwe. No Rota vaccine : Lesotho, Seychelles and Uganda

Figure 4a:

Trend of Rotavirus positives by age group by year (Rwanda, Tanzania, Zambia, and Ethiopia)

Figure 4b:

Trend of Rotavirus positives by age group by year (Eritrea, Kenya, Lesotho, Mauritius, Madagascar, Namibia, Seychelles, Swaziland, Uganda and Zimbabwe).

Figure 5:

Severe dehydration among rotavirus positives and negatives 2010 – 2015 (Rwanda, Tanzania, Zambia, Ethiopia)