|Year : 2021 | Volume
| Issue : 2 | Page : 113-116
Transition towards “end” emicity. When and how can a country possibly declare endemicity of the COVID-19 locally?
Naveen Chawla1, Kiran Kumar Maramraj1, Sougat Ray1, C Sudeep Naidu1, Sunil Goyal2, Ajit Gopinath1
1 Department of Health Services, O/o Directorate General Medical Services (Navy), Government of India, New Delhi, India
2 Director, Institute of Naval Medicine, Mumbai, India
|Date of Submission||01-Oct-2021|
|Date of Decision||07-Oct-2021|
|Date of Acceptance||01-Oct-2021|
|Date of Web Publication||21-Oct-2021|
Surg Capt (Dr) Kiran Kumar Maramraj
Department of Health Services, O/o Directorate General Medical Services (Navy), Government of India, New Delhi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chawla N, Maramraj KK, Ray S, Naidu C S, Goyal S, Gopinath A. Transition towards “end” emicity. When and how can a country possibly declare endemicity of the COVID-19 locally?. J Mar Med Soc 2021;23:113-6
|How to cite this URL:|
Chawla N, Maramraj KK, Ray S, Naidu C S, Goyal S, Gopinath A. Transition towards “end” emicity. When and how can a country possibly declare endemicity of the COVID-19 locally?. J Mar Med Soc [serial online] 2021 [cited 2022 May 17];23:113-6. Available from: https://www.marinemedicalsociety.in/text.asp?2021/23/2/113/328436
COVID-19 transmission since December 2019 has been found to follow a “wave-like” (crest-trough) pattern globally. Till date, India has experienced two nationwide waves since onset of the pandemic. The occurrence of any further wave depends on several factors such as emergence of viral variants of concern (VOC), pockets of susceptible population, herd immunity, mass gatherings, and risk of re-infection or breakthrough infection due to waning of immunity provided by past infection or vaccine, respectively.
The surveillance systems in India are currently indicating a plateaued pattern since July 2021. When cases and mortality are consistently low, and vaccination coverage is being expanded across the country, important questions which arise at this juncture of the pandemic are: Can we declare endemic locally? If yes, how and when? What determines the transition to endemicity? What are the implications of declaring endemicity? This article is intended to address these questions based on the currently available evidence.
| Is Declaration of “End of Pandemic” a Reversal Process of “Pandemic Declaration?”|| |
Declaring a Public Health Emergency of International Concern (PHEIC) is the highest level of alert that the WHO is obliged to declare, raising a signal that a pandemic might be imminent and increased international funding or support is required. Under the 2005 International Health Regulations, states have a legal duty to respond promptly to a PHEIC., The legal definition of a PHEIC is “an extraordinary event that may constitute a public health risk to other countries through international spread of disease and may require an international coordinated response.”, When the epidemic spread over several countries and continents and affected a large percent of the population, the WHO declares it as a pandemic. The sequence of events which led to declaration of COVID-19 pandemic on March 11, 2020, is indicated in [Figure 1].
The process of declaration of “End of PHEIC or pandemic,” however, may not be the exact reversal process of pandemic declaration. The final epidemiological outcome of a disease which was earlier declared as PHEIC/pandemic may vary with various possibilities such as endemicity, elimination, or eradication. In case of COVID-19 pandemic, eradication is unlikely, as the nonhuman reservoirs such as bats are known to exist. Elimination of the disease is less likely as the incidence in most of the areas has not touched the zero, maintaining a low-level transmission, and also, none of the currently available vaccines have been found to be effectively interrupting the transmission. The elimination can be a possible outcome in some isolated regions such as Andaman and Nicobar Islands and Lakshadweep islands, where adequate herd immunity is likely to be achieved with high vaccination coverage. However, the endemicity appears to be the more realistic and likely outcome for most of the countries. An infection is said to be endemic in a population when that infection is constantly maintained at a baseline level in a geographic area without external inputs. In a population with some immune individuals, the product of basic reproduction number (R0) and the proportion of susceptible individuals in the population (S) must be one (R0 X S = 1). COVID-19 can evolve like a flu-like illness, with outbreaks in susceptible subpopulation groups, or else, the disease can transform to a measles-like illness where the disease is effectively controlled in places where people have been vaccinated completely [Figure-1].
| Epidemiological Determinants for Transition Towards Endemicity|| |
We assessed these epidemiological factors using the conventional agent-host-environment model [Table 1]. Viral VOC when emerge with high transmissibility lead to occurrence of large waves. For instance, in India, the massive second wave was predominantly due to highly transmissible Delta variant. However, such high-level transmission also might accelerate the achievement of herd immunity due to natural immunity in the long run. While some recent studies on neutralizing antibodies in countries like Israel have raised doubts over the vaccine effectiveness against the Delta variant and need for a booster dose, the studies in India showed that vaccines continued to be effective against severe COVID-19 caused by the Delta variant. It is also important to understand here that antibody titers are only surrogate markers of immunity and may not reflect the true waning of the immunity. Such studies need to be augmented with the scientific evidence from vaccine effectiveness studies conducted periodically.
|Table 1: COVID-19 pandemic: Epidemiological determinants for transition endemicity based on conventional agent-host-environment model|
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| When and How Do We Declare the Endemicity of COVID-19 Locally?|| |
The declaration of “End of pandemic” is a prerogative of the WHO after due examination of the situation globally through a series of meetings by expert committees. However, prior to that, a country which has achieved adequate control of the pandemic locally should be able to declare endemicity. Based on the assessment of epidemiological factors which determine the transition of the pandemic to endemic, we suggested a decision-making tool to declare the endemicity locally [Table 2]. The essential criteria of the tool are plateaued incidence of COVID-19 cases for 1-year duration, with no surge (occurrence of a large wave) in between, achievement of at least 60% vaccine coverage, and capability to handle high caseload of severe cases (estimates similar to the load of massive second wave). The objective indicators and other criteria of the decision-making tool are given in [Table 2].
|Table 2: COVID-19 Pandemic: Decision making tool for locally declaring the endemicity in a country|
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| Implications of Declaring Endemicity|| |
There are both positive and negative implications when endemicity is declared by a country, after experiencing the pandemic impact for around 2 years. The strategy to clinically categorize the patients based on severity of illness and associated comorbidities, with a rationalized testing and hospital admissions, would be a positive step to ensure that in-hospital and critical cares are available to those who need it the most. Utilization of health-care resources will also be rationalized and other diseases of public health importance would get due importance. On the other side, pace of vaccination is likely to go down compounded by complacency in adhering to COVID-appropriate behavior. Political will and funding for prevention and control activities and research are expected to diminish gradually once endemicity or end of pandemic is declared.
| Conclusion|| |
The endemicity appears to be the more realistic and likely outcome in case of COVID-19 pandemic. Although the transition to endemicity is determined by triangular interaction of agent, host, and environment, the single most important determinant will be viral VOC, which may unpredictably increase transmissibility/ virulence or decrease effectiveness of available diagnostics, vaccines, and therapeutics. Although the declaration of “End of pandemic” is prerogative of the WHO, a country which has achieved adequate vaccine coverage and health-care capabilities and reported a low, plateaued incidence of COVID-19 cases and deaths for around 1-year duration, should be able to declare endemicity locally. However, the implications and outcomes of endemicity-declaration in a country will be driven by a balanced and well-timed decision-making.
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[Table 1], [Table 2]