September 18, Sunday, shall be marked by the second Pulse Polio Day of this year. It needs to be acknowledged and appreciated that all-round efforts have ensured a Wild Poliovirus (WPV) free status for more than 11 years and maintaining certification standard surveillance indicators, at the national level, despite the Covid-19 pandemic. There are several global concerns around polio currently. First, WPV continues to be endemic in Afghanistan and Pakistan. Second, the importation of WPV occurred in countries such as Malawi in 2021 and Mozambique in 2022. Third, genetically linked vaccine-derived poliovirus type 2 was detected in environmental samples in Israel, the UK and USA. The statement of the thirty-second Polio IHR Emergency Committee of the WHO unanimously agreed on June 24 2022, that the risk of international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC). These need to be understood in the context of the big picture in immunisation coverage,
The global immunisation backslides
While India has excellent reasons to be proud of the celebratory note that marked the administration of 2 billion-plus doses of Covid-19 on July 17 2022, the WHO/UNICEF Estimates of National Immunisation Coverage (WUENIC) released on July 15 2022, sounded an alarm that global vaccination coverage continued to decline in 2021. Billed as the “largest sustained decline in childhood vaccinations in approximately 30 years”, an estimated 25 million children missed out on one or more doses of DTP (diphtheria-tetanus-pertussis) through routine immunisation services in 2021 alone. This is 2 million more than those who missed out in 2020 and 6 million more than in 2019, indicating that the post-pandemic tide is yet to turn. The proposed explanations: increased number of children living in conflict and fragile settings where immunisation access can be challenging, increased misinformation and Covid-19-related issues such as service and supply chain disruptions, resource diversion to response efforts and Covid-19 containment measures that limited immunisation service access and availability.
To illustrate the Indian situation, coverage of the first dose of the Measles-containing vaccine declined from 95 per cent in 2019 to 89 per cent in 2021; the context: as part of the South East Region of the WHO, the target for Measles Rubella elimination is 2023. Coverage for the DTP-containing vaccine (both first and third doses) declined by six percentage points each between 2019 and 2021, and the high-profile polio vaccine (third dose) coverage declined by five percentage points too. To give a sense, in absolute numbers, it translates to a doubling of the number of children who were unvaccinated or missed their first dose of DTP from 1.4 million in 2019 to 2.7 million in 2021. At the same time, India needs to be credited for stabilising the backslide at the 2020 level and not letting it worsen in 2021 despite the devastating Delta wave.
A worrying metric and some significant efforts
What makes this a worrying metric is that the decline/stagnation is despite the Union government declaring immunisation as an “essential component of health services” as early as April 15 2020, and subsequent all-round efforts to sustain the gains accrued over the last couple of decades. These included detailed guidelines on safe vaccination during the Covid pandemic restrictions; modifications of micro-plans to identify immunisation sites beyond covid restricted areas; additional logistics to prevent covid transmission at session sites while continuing with immunisation services; and regular review meetings at district, state and national levels. Deep-dive analyses may throw light on the extent to which these were applicable and effective in frontline settings across geographic and regional diversities.
The Intensive Mission Indradhanush (IMI) 3.0 was conducted during February-March 2021 and prioritised 250 high-risk districts, while coverage improvement plans were developed for 192 medium-risk districts. Several states organised additional catch-up campaigns: Assam conducted Mission Ramdhanu from July 2020 for three months, and Rajasthan and Uttar Pradesh conducted campaigns during September-October 2020 and November 2020 to January 2021, respectively. Based on the analysis and the success of IMI 3.0, the country identified 416 districts for conducting Intensified Mission Indradhanush (IMI) 4.0 round in three phases, between February and April 2022. Not only did these contain the declining trend, some of the positive impacts are expected to show up in the next round of WUENIC assessment in 2023.
India has global commitments beyond polio
India is committed to the South-East Asia Region (SEAR) goal of Measles and Rubella Elimination by 2023 and other global goals such as Immunisation Agenda 2030. Coming out of the current backslide is of critical importance. What are the key concerns at this point? Measles and Rubella elimination requires achieving and maintaining high population immunity with at least 95 per cent vaccination coverage with two doses of measles and rubella-containing vaccines in each district. Full Immunisation Coverage (FIC) registered an impressive gain in National Family Health Survey 5 (2019-21) - 76.4 per cent, up from 62 per cent in NFHS-4 (2015-16). At the same time, the persistence of low FIC (NFHS-5) in Uttar Pradesh and the North Eastern states (60-70 per cent) has emerged as a concern. Immunisation among the urban poor and peri-urban areas continues to be an emerging challenge. The National Urban Health Mission (NUHM) is still in the making, and considerable strengthening is called for. Efforts are on to repurpose the CoWIN platform to accommodate the universal immunisation programme, which can provide additional benefits in micro-planning, tracking and monitoring.
The limits of catch-up campaigns
What about catch-up campaigns such as Intensified Mission Indradhanush (IMI)? In programmatic jargon, termed Periodic Intensification of Routine Immunisation (PIRI), these are time-limited, intermittent activities or campaigns used to administer routine vaccinations to under-vaccinated populations and/or raise awareness. These campaign-style approaches to routine vaccine delivery are relevant in specific settings such as conflict-affected populations or Covid-19 lockdowns. A well-designed quasi-experimental evaluation of IMI in the pre-Covid period is illustrative. The IMI increased delivery of 13 infant vaccines, with a median effect of 10.6 per cent; significantly, evidence of a sustained effect during the eight months after implementation ended was not observed. Over the 12 months from the beginning of implementation, the estimated reductions in the number of under-immunised children were large but not statistically significant. The study concluded that despite some gains, other approaches were needed for sustained coverage improvements implying that these campaigns should not become ‘routine’ and not be over-relied upon.
Immunisation data is not an end in itself but a critical marker of the 'health' of primary healthcare. The backslide and stagnation in immunisation indicators are an important signal of deeper post-pandemic challenges that other national health and social sector programmes may be facing but are not yet fully under the scanner. These portend important signals for sustaining the gains towards polio eradication and other global commitments for vaccine-preventable diseases.
(Rajib Dasgupta is Chairperson at the Centre of Social Medicine and Community Health, Jawaharlal Nehru University, New Delhi)
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