On 24 March 2020, a mammoth population of 1.3 billion was restricted to home with announcement of nationwide lockdown by the prime minister of India. The lockdown was aimed to break the chain of transmission and flatten the epidemic curve to curb COVID-19 pandemic. There was suspension of all means of transportation including air, rail and road with the exception of essential services. The educational institutions, industrial establishments, hospitality services were locked. Essential services including food shops, hospitals, medical stores, ATMs, petrol pumps, fire, police were exempted.[12] Subsequently various impositions were partially removed from LD2 and unlock phases has been continuing till now. India consists of 28 heterogeneous states with corresponding dynamics of the COVID-19. [13]
As compared with pre-lockdown period, the doubling rate of new cases was increased from three to eight days during the LD1.[12] The results showed that the rate of evolution of new cases did not differ significantly during the next four phases of lockdown. Singh BP et al. model effects of lockdown on the tempo of COVID-19 and found no significant differences between pre-lockdown rates and LD1 growth rates, but growth rates in LD1 and LD2 differ significantly.[14] Kumar D et al. showed as compared to pre-lockdown and LD1, the doubling time in LD2 was higher. On 14 April 2020, with the end of LD1, the LD2 was announced till 3 May 2020.[15] On 20 April 2020, government allowed some relaxations that include, opening of agricultural businesses such as dairy, aquaculture, plantations and shops selling farm products with proper maintenance of social distancing. Further, the cargo transportation vehicles were allowed.[12] The demographic profile of initial 2500 COVID-19 sufferers revealed 59% belongs to age group of 20 - 49 years, that constitute the working age group.[16]
As on 4 May 2020, LD3 had been continued with some more relaxations as announced by the Ministry of Home Affairs, Government of India. Based on doubling rates, the lockdown areas in the whole country were divided into ‘red zone’, ‘orange zone’, and ‘green zone’ with high, moderate and low doubling rates respectively. In red zones, no movement of public was permitted, while in orange zones, private and hired vehicles are permitted. In green zones, buses with 50% carrying capacity were allowed.[12] Sahoo BK et al. suggested mathematical model, where time dependent infection rate (depend on lockdown) was fitted with Gompertz function and effects of lockdown were modeled. The initial infection rate was 0.15 per day which has come down to about 0.05 per day (about 3 times lower) after 6 weeks of lock down and the downward trend continues, as suggested in the present study.[17] Pai C used SEIR Model (susceptible- exposed-infected-recovered model) to predict the impact of removal of lockdown on 3rd May 2020. They predicted that peak of active infected cases would be around 43,000 in the mid of May, 2020 with 7 to 21% increase in peak value due to relaxation in lockdown strategies. [18] From 18 May 2020, LD4 continued and more power were given to states to demarcate zones. The average daily number of tests have increased from 1,717 (19-25 March) to 131,772 (25-31 May) with an estimated testing shortfall of 4.58 million tests nationally by 31 May 2020.[19]
In view of economical impacts of lockdown, relaxations in ULD1 allowed shopping malls, religious places, hotels and restaurants to reopen. Still no inter-state travel was allowed and night curfew continued. Further as part of ULD2, a number of activities were allowed outside of containment zones, the only exception were educational institutions, international air travel, places of recreation such as swimming pools, gymnasiums, theatres, entertainment parks, bars, auditoriums and assembly halls. The inter-state borders were open. From ULD1 to ULD2 the rate of evolution increases, but after ULD2, rate of evolution has been decreasing. Since ULD3, night curfews were removed and gymnasiums and yoga centers were allowed to open. With LD4, marriages and funerals ceremonies were allowed and religious, political, sports and academic gathering up to 100 persons were allowed.[12] Vaishnav V et al. used group method of data handling to assess the impact of relaxations during lockdown. They reported that apart from relaxations in LD3 and LD4, the increased testing capacity and migration of laborers were important reasons of increased positive cases.[20] During LD5, major relaxations include opening of cinema halls with 50% sitting capacity and reopening of hill stations, beaches and national parks. The results showed that the evolution of death cases due to COVID-19 closely parallels the evolution of new cases of infection .(Figure 3 and 5).
However, Mate A et al used SEIR model to compare range of policies. After the initial lockdown, their simulations demonstrate that even policies that enforce strict physical distancing while returning to normal activity could lead to widespread outbreaks. However, "middle ground" policies that alternate weekly between total lockdown and physical distancing may lead to much lower rates of infection while simultaneously permitting some return to normalcy. [21] Nadim S et al. performed the dynamical analysis of the impact of lockdown on disease transmission. The impact of lockdown of susceptible individuals will have always positive population-level impact for every 0 < r < 1 , where r is lockdown efficacy. The lockdown of susceptible individuals resulted in reduction of the basic reproduction number.[22] Finally, India was quick to implement lockdown and closing its international borders as praised by World Health Organisation as “tough and timely”. [23]