The diphtheria vaccine is among the oldest vaccines in India’s Universal Immunisation Programme, yet cases in the country have been going up over the last few years after showing a remarkable reduction in 2015. That is why the season’s first death due to diphtheria in Delhi has caused an alarm, with doctors assessing their preparedness.
A look at diphtheria, the vaccination programme and the concerns:
Diphtheria is an infectious disease caused by Corynebacterium diphtheria, a bacterium. The primary infection is in the throat and upper airways.
According to the National Health Portal, one type of diphtheria affects the throat and sometimes the tonsils. Another type causes ulcers on the skin; these are more common in the tropics (places where all 12 months have mean temperatures of at least 18 °C). Diphtheria particularly affects children aged 1 to 5 years. In temperate climates diphtheria tends to occur during the colder months.
Diphtheria is fatal in only 5-10% cases. That is why as the monsoon approaches and temperatures start to come down, the season’s first death in Delhi is being seen as a warning sign.
In 2018, Delhi witnessed a diphtheria outbreak. A total of 25 children died in September, followed by 22 in October and 12 in November.
Periodic outbreaks of the disease have been reported in India. Integrated Disease Surveillance Programme (IDSP), National Centre for Disease Control (NCDC), Delhi, reported as many as 7 outbreaks of diphtheria in India during 2014.
In 1978, India launched the Expanded Programme on Immunisation. The first three vaccines in the programme were BCG (against TB). DPT (diphtheria, pertussis, tetanus) and cholera. In 1985, the programme was converted to the Universal Immunisation Programme (UIP). DPT continues to be a part of UIP, which now includes 12 vaccines. It is now incorporated as a pentavalent vaccine, (containing vaccine against diphtheria, pertussis, tetanus [DPT], Hepatitis B and Haemophilus influenzae type B). UIP aims at giving all children born in India all these 12 vaccines free. As per data from the National Family Health Survey 4, the coverage of diphtheria vaccine is 78.4%.
The vintage and coverage of the diphtheria vaccine is also why the government, after the last outbreak in Delhi, decided to commission a study on vaccine hesitancy and ways to deal with it. The study is being done by the Immunisation Technical Support Unit under the ministry of health and family welfare will conduct the study in association with GAVI — an international organisation supported by the Bill and Melinda Gates Foundation working on ensuring vaccine access.
Vaccine hesitancy is a growing problem the world over. The US too has been grappling with it as cases of a polio like illness some time back created panic. States like Minnesota have seen rising vaccine hesitancy, especially among immigrant populations, after Andrew Wakefield, a British doctor who was stripped of his licence to practice and became one of the leading voices against vaccines, personally paid a visit to the state.
The rising trend
Cases have been going up in the last few years. In 2015, as per World Health Organization data, India reported 2,365 cases. This was a steep drop from the 6,094 cases reported the previous year. However, in 2016, 2017 and 2018, the numbers rose successively to 3,380, 5,293 and 8,788.
As per data from the Central Bureau of Health Intelligence, during 2005-2014, India reported 41,672 cases of diphtheria (average 4,167 per year) with 897 deaths (case fatality ratio 2.2%). Ten of the states (Andhra Pradesh, Assam, Delhi, Gujarat, Haryana, Karnataka, Nagaland, Maharashtra, Rajasthan, and West Bengal) accounted for 84% of the cases reported across the country.
In 2017, Manoj Murhekar of National Institute of Epidemiology, Chennai, wrote in the American Journal of Tropical Medicine and Hygiene: “…comparison of the published studies within a state over a period of time suggested that in eight states, majority of the cases were among school-going children and adolescents, whereas in states of Delhi and Uttar Pradesh, most of the cases were among under-five children. Occurrence of diphtheria cases in under-five children reflects low coverage of primary diphtheria vaccination. During the pre-vaccination era globally as well as during eighties in India, high proportion of cases were under-fives. Higher median age of diphtheria cases in most of the studies in India, indicates susceptibility of school-going and adolescent children to diphtheria either on account of low coverage of diphtheria vaccines as well as declining immunity acquired by vaccination or naturally.”
Murhekar documented that children from some communities seem to be affected by diphtheria more than others.