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Covid19 Surveillance: Post Lockdown Strategies and Options

The type and intensity, objectives and broad structure of surveillance activity in three zones

Thomas Kurien, Department of Medicine, Pondicherry Institute of Medical Sciences

Sudhakar Kurapati, Formerly with CDC, World Bank, and USAID  

Ramesh Bhat, NMIMS University, Mumbai 

Arni S. R. Srinivasa Rao, Medical College of Georgia, Augusta University, USA 

As we completed the national lockdown on 3rd may 2020 and started the Lockdown 3.0 with some relaxations. The question on every body’s mind is ‘What next?’ We need to be clear about what we want to achieve in the lockdown 3.0 and after that. As of 4th May 2020, we have nearly 42836 confirmed cases nationally, with nearly 1389 (3.24%) deaths across the nation . These infections, to date, have substantial geographic variability. Three states of Delhi, Maharashtra, and Gujarat account for 54% of cases. Currently, 170 districts (23%) out of all districts have been designated as red zone districts . It is expected that more than 96% of the affected recover with time as they develop antibodies against the virus, providing them immunity against further infection. However, what we have not achieved at present is that almost 99% of the population remains vulnerable to the virus with very low levels of herd immunity to prevent further waves of COVID19 infection and surges in the community. There seems to be a consensus that we will move to a differential strategy with the aim of reducing the rapid spread of the epidemic surge in hot spots (Red Zones) and mortality particularly in more vulnerable people of the country while at the same time reducing the economic consequences to poor communities who are maximally affected with loss of wages and in the less unaffected areas (Green and Yellow zones). The success of this differential strategy would largely depend on the type and intensity of surveillance activity in the three zones of the country with the following objectives:

  • To identify emerging new infections in the community without delay so as to initiate strategies to prevent surges and increase in mortality
  • To identify sub-populations in hot spots which are protected by immunity so that they can be allowed to participate in normal activity and thus reduce economic consequences to affected families
  • To identify the magnitude of herd immunity in the general population at different zones of the country so as to stop emergency distancing measures instituted in the country and go back to normal activities.

The surveillance strategies must identify emerging new infections in communities without delay so as to initiate strategies to prevent surges and increase in mortality. The differential strategy may focus on the following:


1.      Hot spots (Red Zone) Surveillance

These geographical areas have already been established as high prevalent areas of the country. It is essential intensive distancing and lockout continue at these hotspots. The objective is, therefore, to prevent surges and increase in mortality. Intensive tracking of infections in these areas is not required since more than 20% of subjects with COVID are asymptomatic. Everyone should be considered as likely COVID positive, and generalized and effective quarantine measures must be the focus. It has been clearly shown during the lockdown period that this action can reduce the surges of new cases and reduce mortality. However, to understand the progress of the epidemic, low-level syndromic sentinel surveillance in health center/hospital will be required. In addition, in selected areas, where access to health care is poor additional set-up to monitor pneumonia, and pneumonia mortality must be established. Certainly, all cases with fever or upper respiratory symptoms must be considered as COVID19 and subject to isolation and quarantine accordingly. Laboratory testing in these cases is likely to go wrong as sensitivity and specificity of available tests are still less (60-80%) than optimum.

  1. Moderate Intensity (Yellow Zones) Surveillance

These are high-risk areas that can quickly turn into hot spots in the country if adequate and timely interventions are not instituted without delay. Hospital-based surveillance looking at severe cases and mortality will not suffice in these zones. The intensity of surveillance must be maximum in these areas. Extensive laboratory testing of all symptomatic and even routine normal people using ‘Testing Booths’ will need to be instituted in these areas. Testing people coming for shopping and travelling in buses, etc., in the region will give a handle regarding emerging new infections and the trend of rising or lowering of the infections in the community. Active surveillance using existing health infrastructure of health workers will be needed to monitor fever and pneumonia as a priority in these geographical areas so that timely information is obtained, and appropriate local strategies can be initiated to prevent spread. Workplace surveillance of symptoms can be undertaken by companies and reported to public health authorities

3. Low Intensity (Green Zone) Surveillance

While the spread of COVID19 from high-intensity areas to low-intensity areas is prevented by restrictions of human travel/contact to the maximum feasible. Care must be taken to monitor these areas for emerging infections. At this point, low-intensity zones constitute the largest sections of the country involving many villages of India with poor health infrastructure for intensive surveillance. Therefore, technology-based surveillance of ‘Fever’ may need to be given higher priority than surveillance involving laboratory-based COVID testing methods on symptomatic people. Potential outbreaks should be suspected and investigated if any geographical area shows unusual fever outbreaks. Some innovative technologies have been identified in some countries using Self-reporting thermometers and hand-held devices by health care workers in the villages. Rumor registry is another mechanism that can be activated and used for monitoring unusual events in the community.

4. Identify sub-populations in hot spots which are protected by immunity

It will be important to identify sub-populations in hot spots that are protected by immunity so that they can be allowed to participate in normal activity and thus reduce economic consequences to affected families in restricted areas. Antibody tests in high-intensity hot spots will be able to identify a protected population that have recovered from the infection. History of patient’s health alone is not sufficient to detect this subpopulation since up to 25-30% of the population are asymptomatic. This is particularly relevant in hotspots areas where a large number of people have had infections. It will not be much useful in the very moderate and low-intensity areas. Protected subpopulation can be provided working passes so that the economic impact in these areas can be minimized.

5. Identify the magnitude of herd immunity

The identification of the magnitude of herd immunity in the general population at yellow and green zones of the country so as to stop emergency distancing measures instituted in the country. As we gradually reduce the restrictions on movement and work placed on our population for reducing the spread of COVID19 infection, we need to understand a point in time when we can go back to normal activity. It is possible that if more than 40-50% of the population are protected by antibodies and not susceptible to further infection, it will be possible to wind down the restrictions in the area. This objective is likely to succeed over a 6-18 months period in different regions of the country if we go by the history of  H1N1 epidemic. In high-intensity areas, it will occur faster, and in lower intensity areas, this will occur over a greater time period unless a vaccine becomes available. Information on herd immunity can be obtained by properly planned repeated surveys on representative populations in these different geographical areas over 3-6 months interval. This can easily be done by public health departments in different government and private medical colleges in the country under ICMR guidance.

 6. Developing Effective Surveillance Response

Surveillance, by definition, is the collection of data for appropriate public health action. Any recommendation on surveillance must be accompanied by specific actions based on the emerging data. This graded response has been very well documented in the document, which has been in the public domain (Report on Expert Committee on Strategy for Easing Lockdown Restrictions by Government of Kerala ) and this seems appropriate as a corollary to this document on surveillance (Refer Appendix 1 pages 16-23 of the report). The action plan clearly lists a three-phased approach to reduce the distancing policy based on the risk profile of the districts. But it is evident that some sort of distancing will continue all over the country till herd immunity develops in the population over time or vaccine becomes available, or an effective intervention is identified to reduce case fatality of COVID19 infection.

The objectives of the surveillance policy would be to differentially allocate resources to strengthen care and support of the affected population in high prevalent zones at the same time reduce the economic burden of the population in the less affected zones of the country without increased risk of epidemic surges and change in the status of the epidemic category of districts from lower to higher levels of prevalence.

Integration and Coordination of Surveillance Activities for COVID19

A wide range of surveillance systems has been developed in India over the past few decades, which can be used effectively to keep track of COVID19 epidemic in India. By pooling the resources, involving the field and laboratory personnel and management systems, COVID19 surveillance system can quickly be established and operationalized immediately. As an integral part of the country’s response to COVID19, this activity needs to be given the highest priority and necessary support.

Resource requirements for this will need to be identified as a priority, particularly for rapidly strengthening IDSP in all states in India.

 Integrated Disease Surveillance Programme (IDSP)

IDSP is primarily meant to detect and respond to emerging epidemics like COVID19. It is a decentralized program having both syndromic and laboratory-based surveillance components. It is IT-enabled with focus at district and state levels to monitor disease trends and respond to outbreaks in the early rising phase through trained Rapid Response Team (RRTs). However, the programme has not been uniformly successful in all the states of India. The established components of surveillance activities are particularly needed for COVID surveillance. Other disease surveillance systems can be integrated at this point with IDSP to monitor trends of COVID in different settings. For example, HIV Sentinel Surveillance (HSS) system which has extensive coverage of many high-risk populations where sentinel surveillance can be used to detect change COVID prevalence in hotspots and the National Polio Surveillance Project (NPSP) has an excellent laboratory component and can be used in COVID confirmation in all districts.

Develop and establish COVID19 Sentinel Surveillance (CSS) system

Additional surveillance for COVID19 is needed to collect data from the special group, particularly asymptomatic people who may not be detected by usual disease-based surveillance systems. These units must conduct active surveillance asymptomatic carriers who cannot be identified through existing systems to get laboratory confirmation. COVID surveillance must be established in places where people gather and get together like bus stations, religious places, malls, schools, and educational institutions and construction sites. This is particularly important in medium-prevalence zones to prevent them from becoming new hot zones of infection.

Management System to Improve the Efficiency of Surveillance:

There will be a need to put a management system in place which may constitute a district-level coordination committee under the leadership of District Magistrate/Collector with District Medical and Health Officer (DMHO) as the convener. Representatives of ICMR, vertical disease control programs, medical colleges, health NGOs, civil society networks, IMA, etc., must be part of this coordinating body as envisaged under IDSP. The key role of this committee would be to map and identify high-risk areas that require a wide range of intervention and work closely with key district level officers, local self-government members, civil society representatives. The district-level committee would also be empowered to plan and coordinate for an essential package of services for current and future COVID19 waves. Once designed, this essential package kicks in whenever there is a semblance of a COVID19 outbreak.


The mantra echoing in all social media and many scientific circles is ‘Test, Test, and Test’. But testing to collect data is only one part of the necessary surveillance activity to guide health policy. The efficiency of testing to control the epidemic will improve if the type of differential testing is tailored based on the levels of prevalence in the geographical region strongly linked to specific predetermined public health action. Different types of COVID tests are needed for different regions, and it includes test (a) to diagnose and isolate affected individual, (b) to detect protected individuals so they can resume normal activity and (c) to determine the pattern of involvement and magnitude of herd immunity as a measured to go back to normal social activity for the population.

It is essential to integrate all surveillance activities in the country to tackle this pandemic. This can be achieved by strengthening the Integrated Disease Surveillance Program, which has already been established for this specific purpose of epidemic control in all states in India. Data collection and response should be decentralized at the district level and will need to be different based on the prevalence of the disease in the area during the post lockdown period and beyond. As coronavirus is going to remain a threat in times to come, strengthening the structure and operational aspects of the surveillance system now will help not only the current crisis but also in the post-vaccine surveillance phase. Certainly, the surveillance system will be pivotal for monitoring the safety and efficacy issues, vaccine immunization distribution, and adverse events reporting, At this critical juncture of COVID19 pandemic, the country must take this opportunity to increase investments on surveillance by strengthening IDSP across the country for not only addressing the immediate public health challenges but also for long term benefits which will accrue over the years.


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