The study found that proactive intervention started in the early phase of the pandemic in the country. Initially, the interventions are linked to controlling the source of infection and gradually it shifted to blocking the transmission and prevention of new infections. The median doubling time gradually increased from 1.4 days in phase one to 18.6 days in phase seven. Similarly, the recovery rate increased gradually to 64.57% in phase seven. However, R0 decreased gradually after initial fluctuations to a lower level of around 1.2. Death rate however remained at a lower level around 3.0% throughout the study period. Intervention scores gradually increased till the end of the march, however after this decreasing trend was observed.
The initial intervention was found to be limited to entering the infection in the country which was logically correct as the pandemic was started in the countries outside India. This was followed by the prevention of new infections and followed by blocking the transmission. However, in the latter part of March 2020, the intervention became multi-faceted with the involvement of all the sectors. A study by Pan et al. (2020) in Wuhan, China showed that the sequence of interventions in China was mainly related to controlling the source of infection and blocking the transmission routes followed by the prevention of new infections. Singapore's government interventions started were related to the screening of the cases, testing, tracing, and treating the cases followed by restriction of the flights from the other countries by the end of January. (Wong et al. 2020) Sri Lanka, which also reported a very few numbers of cases till now acted in a similar way of starting with the health system, strengthening and testing, treating and tracing of the cases, followed by the screening of the cases and restriction of entry points to the country. (Jayatilleke et al., 2020) Both the countries shared few interventions early in the period, however India failed to restrict the cases entering early in the period.
This study shows the R0 values gradually decreased in these seven phases of the pandemic in India. This decreasing trend of R0 may be due to the initial availability of a large number of susceptible individuals which gradually decreased with time to settle the R0 value to a lower level. Interventions linked to decrease contact of the infected individuals with suspectable individuals. Similarly, the trend of R0 values was observed in Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) in the past. (Trillia A, 2020) In the current pandemic also, a study conducted by Chong YC et al. (2020) found that the trend of R0 decreased over time with few peaks in between. A study by You C et al. (2020) found that the trend of the R0 decreased over time in different states of China. However, the study by Najafi et al., 2020 in the study found to have increasing R0 values after a period of decreasing trend. This increasing trend may be due to decreased stringency of the interventions in the selected province of Iran.
The median doubling time in this study was found to be increasing throughout the study period with fluctuations in phase two and phase three of the study period. This increase in median doubling time was noted after the end of phase three, which had the highest stringency score in the entire study period. The delay in the rise in doubling time is because the effect of the intervention may take some time to appear in the epidemiological parameters. A study by Roudrogriz et al. (2020) showed the fluctuating nature of the median doubling time when compared with the other studies. This fluctuation limited to the initial phase of the pandemic as observed in the current study. A study by Zhou et al. (2020) found that the early doubling time of countries like Thailand, Australia, Malaysia, Vietnam, the doubling time decreased whereas in countries like Italy, Belarus, and the Philippines the doubling time increase over time. However, both R0 and median doubling time related to testing and tracing strategy.
The interventions that undertook by the govt. of India reached maximum stringency level in the latter part of March 2020, i.e. in the third phase of the study. Despite the interventions, the number of cases began to rise in phase four and later in the study period. This may be related to the poor stringency of the interventions or may be due to poor screening of the cases that may lead to continued transmission in the background. In the pre-lock down phase, the relation between public awareness and public health laws were found to be significantly associated with the median doubling time. Public awareness was found to be positively associated with R0. This may be due to the fact that the implementation of public awareness activity may not have transformed into action immediately. However, implementation of the public health laws was found to be negatively associated with the R0, i.e. with strict implementation of public health laws, the R0 value decreased. No relation was observed between the factors like social distancing, immigration, out migration found not statistically significant with the R0 and MDT. This may be attributed to the fact that the short period of action of these interventions in the pre lockdown era. In the lockdown and post-lockdown period, the interventions like the restriction of industry/ agriculture and construction, restriction of local transport were found to be negatively associated with MDT and positively associated with R0. A study by Pan et al. (2020) showed that the R0 value decreased with the non-pharmacological interventions. Various modelling studies have shown the impact of the interventions on the R0. A study by Davies et al., (2020) & Chaudhary et al. (2020) had found each individual non-pharmacological intervention had some impact on the decrease in the R0. Similar results were obtained by Lai S, 2020 in their study in China. This opposite relation between the intervention and the R0 and median doubling time may be due to the fact that the closure of the workplaces released many migrant workers who moved to their hometown which might have helped in the seeding of the COVID 19 in the general public. The impact of which was observed in terms of an increase in caseload in the states contributing to a large number of migrant workers. (Rath et al., 2020) Other interventions also remained nonsignificant in the lockdown and the post-lockdown phase, maybe because of the higher impact of the above-discussed variables.
The study is limited by the fact that the ground level stringency was not assessed during the study. Similarly, the interventions in the later phase might have varied depending upon the number of containment zones in each state. This is one of the studies which analysed the impact of the various interventions in different phases of the pandemic in the country, which accounts for the second-highest number of cases in the world.