Back to the future—of immunisations

Abstract

Out with the old, in with the new. The emergence of COVID-19 underscored the need for a new vaccine to halt the pandemic while catastrophically disrupting routine vaccinations worldwide. With unprecedented focus on vaccine development, came lockdowns, border closures, overburdened health services and economic distress that undid generations of hard-earned vaccination successes by disrupting mass immunisation programmes. In 2021, data from the UN revealed the worst regress in global vaccination coverage in more than 30 years for several diseases. The rapid pace of the development of vaccines against COVID-19, although heralded as a public health triumph, met with widespread vaccine hesitancy that was bolstered by misinformation and escalating anti-vaccine sentiments, furthering the decline in routine immunisations. Although the COVID-19 pandemic disrupted all health services across the globe, childhood immunisation was hit particularly hard. WHO estimated that, in 2021, 25 million children under the age of 1 year missed receiving basic vaccines. An increase in outbreaks of diphtheria, measles, polio, and yellow fever was seen in over 100 countries during the pandemic. Addressing these disruptions, UNICEF Executive Director, Catherine Russell said: “Routine vaccines are typically a child's first entry into their health system and so children who miss out on their early vaccines are at added risk of being cut out of health care in the long run.” For the child, routine vaccination is the first step towards and the foundation for lifelong protection from vaccine-preventable diseases. In an effort to restore childhood vaccinations to pre-pandemic levels or better, WHO, UNICEF, Gavi, the Vaccine Alliance, and the Bill & Melinda Gates Foundation, along with other health partners, announced “The Big Catch-Up” during World Immunization Week (April 24–30, 2023). A targeted effort aimed at 20 countries that are home to three-quarters of the children who missed vaccinations in 2021, countries involved in The Big Catch-Up include Afghanistan, Brazil, Ethiopia, India, Myanmar, Tanzania, and Viet Nam. What challenges might an immense effort such as this be expected to face? The salient features of this plan include strengthening health-care workforces and health service delivery, but what catches the eye is “building trust and demand for vaccines within communities”. To what extent is distrust and exacerbation of vaccine hesitancy due to the pandemic impeding the implementation of childhood immunisation programmes? While expressing concerns about escalating disinformation, Kate O’Brien, WHO Immunisation Director, said: “The main reason that kids are unvaccinated is not anti-vax. The main reason why children are unvaccinated has to be access to services, quality of services, and full availability of programmes.” Barriers and inequality in access to vaccines in low-income and middle-income countries (LMICs) can be a broad, contextual mix of demographic, geographical, educational, and socioeconomic factors. Awareness of immunisation services and the benefits of vaccination, travel distance to a health-care facility, cost and safety of travel, and security in areas of political instability are some limiting factors. Multiple vaccinations with multi-dose schedules compound these challenges, urging the development of simplified schedules in LMICs. Studies that examine transitioning to a reduced-dose schedule for pneumococcal vaccines for children in Africa are notable in this regard. Amid the global decline in vaccination coverage, a few tales of endurance lift the pall of gloom. India registered a strong resurgence in essential immunisations in 2022, Kenya engaged local leaders to increase immunisation among its nomadic populations, and Uganda sustained high vaccination rates during the pandemic. With much written about the burden of the pandemic borne by LMICs, their pioneering efforts that informed global policies must be spoken of in equal measure. South Africa's sequencing drive, leading to the identification of the Omicron variant of SARS-CoV-2, and India's leveraging of its domestic manufacturing capacity to develop intranasal and injectable COVID-19 vaccines remain memorable examples. Although tales of resilience emerge from all calamities, the one legacy of the COVID-19 pandemic that we can wholly embrace is the renewed interest in vaccinology. Adenovirus-vectored vaccines, previously used against Ebola virus, were developed and administered against COVID-19 at a pandemic scale with demonstrable success. Evidence of the effectiveness and safety of mRNA vaccines against COVID-19 is driving further research in applying mRNA technologies to thwart existing diseases and future pandemics. This is the new we take forward; the hope of advancement and restored trust in vaccines.