Cyclical curbs, relaxations likely to help
A cycle of 50 days of hard lockdown followed by 30 days of easing may be effective in reducing the number of Covid-19 deaths and hospitalisations while not hobbling the economy beyond repair, a 16-nation modelling study has suggested.
This approach, detailed in a paper published in the European Journal of Epidemiology on Wednesday, may prolong the pandemic to beyond 18 months but will reduce R0, the average number of people infected by a single patient. The study comes as India is in the fourth phase of a nationwide lockdown that began on March 25.
India was one of the 16 countries for which the modelling was done and the cyclical lockdown-easing approach was seen to reduce deaths by 98%, compared to a scenario with no intervention.
“This intermittent combination of strict social distancing, and a relatively relaxed period, with efficient testing, case isolation, contact tracing and shielding the vulnerable, may allow populations and their national economies to ‘breathe’ at intervals--a potential that might make this solution more sustainable, especially in resource-poor regions,” said Rajiv Chowdhury, a global health epidemiologist at the University of Cambridge and the paper’s lead author.
In their study, a group of scientists found that strategies focusing on suppression of the disease--such as enforced physical distancing and strict measures--are more effective than those aimed at mitigation--general social distancing, hygiene rules, case-based isolation and shielding of vulnerable groups.
The study considered three scenarios in four bands of countries: high, upper-middle, lower-middle and low income. India was in the third band, along with Bangladesh, Pakistan and Nigeria.
The first scenario modelled the impact of no measures and predicted 7.8 million deaths across 16 countries and 200-day duration of the pandemic. In India, around 4.6 million deaths were predicted. The R0 was assumed at 2.2.
The second scenario modelled a rolling cycle of 50-day mitigation followed by a 30-day relaxation. This strategy was still insufficient in controlling the number of deaths and intensive care unit (ICU) hospitalisations and predicted 3.5 million deaths in 12-18 months. In India, 2.09 million deaths were predicted. The R0 was assumed at 0.8
The final scenario involved a rolling cycle of stricter, 50-day suppression measures followed by a 30-day relaxing. Since more individuals remain susceptible at the end of each cycle, such an approach would result in a longer pandemic, lasting beyond 18 months in all countries. However, a significantly smaller number of people--just over 130,000--would die. In India, the predicted deaths stood at 15,379. The R0 was assumed at 0.5
“There is no simple answer to the question of which strategy to choose. Countries--particularly low-income countries--will have to weigh up the dilemma of preventing Covid-19 related deaths and public health system failure with the long-term economic collapse and hardship,” said Oscar Franco from the University of Bern, Switzerland, and another author of the report.
Chowdhury highlighted a specific takeaway for India. He said that in regions with large populations where wide-scale testing and rigorous contact-tracing for a prolonged time are not feasible and critical care infrastructures (ICU beds) are inadequate, the proposed cyclical suppression-relaxation strategy could be considered to strike a balance between keeping the ICU bed requirements within a manageable limit and allowing the local economy to open intermittently.
“If local containment measures are done efficiently [as shown in Kerala] or current plans of zonal lockdowns of the hotspots are well managed [with no significant second wave nationwide], this cyclical strategy may not be needed in such settings,” he added.
Some Indian experts disagreed and said other forms of dynamic lockdown may be more useful.
Snehal Shekatkar, a professor at the Centre for Modelling and Simulation, Savitribai Phule Pune University, said several lockdowns scattered over a period of about two years might drastically hamper the economy, rendering it impractical.
“Moreover, during any lockdown, it is extremely difficult to maintain the basic reproduction number R0 below 1 as assumed in the study. Also, ramping up testing is known to lead to shortening of a lockdown, and the study has not considered this possibility. It is quite possible that even for high R0, increased testing would make such long and strict lockdowns unnecessary,” he said.
He suggested an alternative--proposed by other studies including by the Indian Scientists’ Response to Covid, a coalition of 500 leading scientists--called a staggered lockdown, in which subpopulations experience alternate lockdowns. “This has been shown to be much more effective and economically feasible than periodic lockdowns,” he added.