Dear Tusharkanti Dey and all,
You wrote: "I would like to know if imposing such intermittent lock down has any effect on the spread of coronavirus, and, if, how? Is there any epidemiological rationale supported by epidemiological modelling?"
As a HIFA volunteer I have looked into this question with a limited literature search and my preliminary findings are shown below. I hope this is helpful and look forward to your comments.
Gladson J. V
Intermittent or rolling lockdown measures take place when strict social distancing measures are applied and lifted periodically. This strategy has been described as a potentially effective measure to minimise uncertainty in both effective R values, and in the severity of the virus (i.e. the proportion of cases requiring ICU admission) (1) A recent paper mathematically modelled the effects of either a strict 50-day suppression or a 50-day mitigation, followed by 30 days of relaxation (during which businesses are allowed to reopen, with basic hygiene measure kept in place), in 16 economically diverse countries. In these models, a strict 50-day lockdown, that reduces the effective R value to 0.5, prevented ICU beds overload and led to considerably fewer deaths (130,000 during 18 months in the 16 countries they modelled) compared to a more relaxed 50-day mitigation/30-day relaxation cycle (~3.5 million predicted deaths globally) and under no-intervention (counter-factual) scenario (8 million predicted deaths) (2) To further contextualize the value of such concept, a subsequent paper estimated that (1) a single, one-off lockdown will be insufficient to bring the pandemic under control, and (2) secondary peaks would be larger than the first, without continued restrictions (3)
In another paper, a compartmental model was used to evaluate 2 scenarios: (A) an intermittent lockdown; (B) a gradual relaxation of the lockdown. Predicted ICU and non-ICU demand was compared with the peak in hospital bed use observed in April 2020. The results were - Under scenario A, while ICU demand will remain below the peak, the number of non-ICU will substantially rise and will exceed it (133%; 95% confidence interval [CI]: 94-171). Under scenario B, a rise in ICU and non-ICU demand will start in July and will progressively increase over the summer 2020, reaching 95% (95% CI: 71-121) and 237% (95% CI: 191-282) of the April peak (4)
Prof. Uri Alon and his graduate students Omer Karin and Yael Korem-Kohanim, together with senior engineer Boaz Dudovich of Applied Materials, suggest, based on an epidemiological model they developed, a policy that effectively suppresses the coronavirus and, at the same time, allows sustainable, albeit reduced, economic activity. The model is based on intermittent lockdown: five days of lockdown and two days of work every week. In this way, the virus replication number (the number of people infected by each infectious person) drops below one - the magic number that causes the epidemic to decline. (5) A four-day work/ten-day lockdown strategy is even better, allowing those infected at work to cease becoming infectious at home. Prof. Alon carefully suggests that, after several such cycles, the number of infected people will drop dramatically. The epidemic can thus be contained until sufficient testing, effective treatment, or a vaccine is developed, which will remove the need for a lockdown. (5)
Intermittent lockdown may be the only viable option for countries that cannot deploy sufficient testing in a timely manner. It allows millions to work two days a week, sustaining key economic sectors. People will hold a 40% position instead of being completely unemployed - an economic aand psychological game-changer. (5)
While another study found Long-term social distancing at 6 and 8-week durations are viable but less effective. The study was based on an agent-based model to examine the impacts of epidemic control over 480 days. A limited control baseline of case isolation and household member quarantining is used. They measured the impact of lockdown duration and start date on final infection attack sizes. Then they applied a 3-month gradual exit strategy, immediately re-opening schools and easing workplace distancing measures, and compare this to long-term social distancing measures. (6)
As per the Indian Scientists' Response to COVID-19 (ISRC), a staggered resumption of work following the end of the nationwide lockdown may reduce peak hospitalisations due to COVID-19 to almost 50% as compared with a total resumption that would force authorities to impose intermittent lockdowns to contain surges in the incidence of the disease, a model built by a group of scientists estimates. (7)
Hence, different opinion has been found, consisting of both, in favour of as well as not in favour of Intermittent lockdown.
1. Ferguson NM, Laydon D, Nedjati-Gilani G, Imai N, Ainslie K, Baguelin M, et al. Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand. Imperial College COVID-19 Response Team. 2020. https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-...
2. Chowdhury R, Heng K, Shawon MSR, Goh G, Okonofua D, Ochoa-Rosales C, et al. Dynamic interventions to control COVID-19 pandemic: a multivariate prediction modelling study comparing 16 worldwide countries. Eur J Epidemiol. 2020;35:389-99.
3. Kissler SM, Tedijanto C, Goldstein E, Grad YH, Lipsitch M. Projecting the transmission dynamics of SARS-CoV-2 through the postpandemic period. Science. 2020;368(6493):860-8.
4. Bollon J, Paganini M, Nava CR, et al. Predicted Effects of Stopping COVID-19 Lockdown on Italian Hospital Demand [published online ahead of print, 2020 May 18]. Disaster Med Public Health Prep. 2020;1-5. doi:10.1017/dmp.2020.157
5. Adaptive cyclic exit strategies from lockdown to suppress COVID-19 and allow economic activity Omer Karin1 , Yinon M. Bar-On2 , Tomer Milo1 , Itay Katzir1 , Avi Mayo1 , Yael Korem1 , Boaz Dudovich3 , Eran Yashiv4 , Amos J. Zehavi5 , Nadav Davidovitch6 , Ron Milo2 , Uri Alon1,*
6. Modelling lockdown and exit strategies for COVID-19 in Singapore Borame L. Dickens a,1 , Joel R. Kooa,1 , Jue Tao Lima , Minah Parka , Sharon Quayea , Haoyang Suna , Yinxiaohe Suna , Rachael Pung b , Annelies Wilder-Smithc,d, Louis Yi Ann Chai e,f , Vernon J. Leea,b , Alex R. Cooka
7. Indian Scientists' Response to COVID-19 (ISRC) https://indscicov.in/
HIFA profile: Gladson Vaghela is a Medical Student at the GMERS Medical College Gandhinagar, India and has a professional interest in medicine. Email address: gladsonsamuel75 AT gmail.com