India needs to expand diphtheria vaccine coverage, doctors have said as they warn of dropping herd immunity in the country.
Herd immunity refers to when vaccination coverage against a disease is sufficient to stymie the risk of further transmission. The diphtheria vaccine is credited with effecting a ninety percent reduction in disease cases between 1980 and 2000 but, as noted by the World Health Organization (WHO), the disease remains a “significant child health problem in countries with poor EPI coverage.” EPI refers to the Expanded Programme of Immunisation developed by the WHO, which includes the diphtheria vaccine. The diphtheria vaccine is also included in the WHO’s list of essential medicines.
Diphtheria is a condition caused by Corynebacterium diphtheria bacterium, which infects the throat and upper airways and is fatal in between five and ten percent of cases. In India, cases have been increasing in recent years, reaching a thirty year-high in 2018. This is despite the diphtheria vaccine being included under the country’s Universal Immunisation Programme (UIP). As such, public health experts have asserted that India accounts for up to ninety percent of the world’s diphtheria cases.
Diphtheria vaccine coverage in the 2015-16 period stood at around eighty percent. In recent years, mistrust of vaccines and a misperception that the disease is no longer a public health threat have driven declining vaccination rates. According to a 2017 study, “information about coverage of diphtheria boosters is not routinely collected through these surveys, but is expected to be low. Few studies also indicate low diphtheria immunity among school-going children and adults.”
For immunisation against diphtheria, booster shots are recommended to maintain immunity during later childhood and adolescence. Lagging levels of booster shots in these periods could be one explanation as to why India witnesses significant numbers of diphtheria cases among young adults. Raising awareness of the importance of diphtheria vaccinations and booster shots will be necessary in India’s efforts to fight the disease.