40 years of smallpox eradication and lessons learned for COVID-19 response

There were countless challenges in eradicating smallpox, but there were some factors that helped the situation as well. Smallpox is contagious only when the characteristic rash appears, so it is more easy to identify infectious people and isolate them. Further, the incubation period is also rather short, so the disease cannot travel very far before it is noticed. But being a respiratory disease, COVID-19 symptoms are more generalized and people are infectious even before they appear. 

Smallpox also did not have animal vectors - compare that to a disease like dengue and one understands the challenges of containment in that situation.

The smallpox eradication programme was based on vaccines which is of course different from the current situation. However, the innovations and methods of reaching large, remote populations and identifying and inoculating at-risk subgroups is more relevant than ever.

The ISEP programme was actually rather underfunded; it had a $2.4 million budget for every year. In 1967, a village in Nigeria was short of vaccines after an outbreak occurred, and protocol dictated that everyone in the vicinity be vaccinated, but this was not possible. Therefore, it was decided that only those at high risk of contagion would be vaccinated. This was one of the first examples of the ring vaccination principle; only those who had been in close contact with infected people in the duration of the incubation period (taken to be 2 weeks) would be vaccinated. 

How do you identify those at high risk? Health workers in Nigeria worked with community members and tracked the daily routine of villagers and zoned in on activities such as visits to markets. This way, they were able to map the interactions of people and identify those that were likely to cross paths with infected people. Surveillance and containment strategies, which include measures such as contact tracing were inspired by these events. 

Read more: What is contact tracing?

In the COVID-19 scenario, gathering data on the spread of disease using such surveillance methods could go a long way. Learning from the smallpox response, local health workers and communities should be included so that data collection can be more penetrative. This may also increase the trust between governments and marginalized communities. With the advent of GPS and GIS mapping, surveillance can be strengthened further. While Aarogya Setu, a similar app by the Indian government in the wake of COVID-19 has been launched, privacy concerns have been raised, and these will have to be addressed for widespread adoption. 

How can the ring vaccination principle be applied in this situation? Testing should be proactive and focused on those at high risk - frontline health workers, those who have been in contact with infected people, as well as those with travel history. This is already a part of the MOHFW action plan, and testing capacity has been improved as well. Although increasing, large scale testing of people remains low while rapid action test kits have proved to be faulty; these are two areas that are critical in appropriate intervention and must be addressed.

Read more: Potential COVID-19 vaccine targets

During smallpox interventions, local health workers and information had to be tapped into because there were budgetary constraints. This actually turned out to be a blessing in disguise. Given the diverse health structures and realities of every country, one-size-fits-all approaches were just not feasible. 

Traditionally, public health interventions followed a top-down approach and local sources were undermined. Experiences from the field in the smallpox interventions showed that local political and infrastructural conditions required careful study to finetune the implementation of programmes. 

There are parallels to this in the current situation. An article published in the Lancet this week suggests that the blanket adoption of western methods of intervention, such as stringent lockdowns will hurt poor countries. 

For starters, the context of western countries is completely different; demographically, the average age there is much higher than in a country like India which accounts for lower risk of COVID-19 mortality. Further, the banning of public transport, which is the primary way for the average citizen to get around, will probably end up hurting the country more than enforcing blanket lockdowns.

There has been a reduction of 69% in MMR vaccination (vaccine against measles) in children in the country, and 50% reduction in clinic attendance for acute cardiac events. Local realities of a region need to be taken into consideration before intervening. In India, this could mean using primary health workers to undertake syndromic diagnosis of people where sophisticated testing methods are not available. This means looking for the vast range of symptoms that COVID-19 presents and identifying these to place people in isolation.

Read more: Why is it taking so long to develop a COVID-19 vaccine?

The country is now moving towards easing restrictions in low risk ‘green zones’ and allowing some economic activity to restart. This should perhaps have been the approach from the start so that the poor were not adversely affected.

The response to the COVID-19 pandemic has seen unprecedented scientific partnerships and clinical trials, and therapies have been tested at break-neck speed. This is not the first pandemic the world has endured - the good news is that some lessons seem to have been learned. There will always be room for improvement and we will come out of this crisis with new insights and technologies.