Covid and Indian society - Endemic or not

Let us see how can Covid-19 in India become an endemic

Covid and Indian society - Endemic or not

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• The story: WHO's chief scientist Dr Soumya Swaminathan said India was perhaps entering a stage of endemicity. Earlier in 2021, scientists had indicated in a survey carried out by the journal Nature that the SARS-CoV-2 virus is set to become endemic and would continue to circulate in pockets of the global population.
• Endemicity: "Endemic" means something that is present all the time. For example, influenza is endemic, unlike smallpox which has been eradicated.

1. Only those pathogens can be eradicated that don’t have animals (another species) as a reservoir.
2. Smallpox and polio are human virus examples, rinderpest is a cattle virus. This means if there is a virus/pathogen that is present in some animal reservoir like bats, camels or civet cats, then it can transmit again once the level of immunity wanes in the population against the disease caused by it.
3. In the case of novel coronavirus disease, it will continue to circulate as it is present in the animal reservoir. This also means that it will cause disease to the extent that people have had no vaccination against or exposure.
4. If, however, enough people are vaccinated or have been exposed to the infection, then the virus will cause symptomatic infection but not disease. So, that is what is considered becoming endemic – it is there but not causing disease.

• When will it become endemic: That will depend on its pace and mutations. There are variables and no clear answer regarding when the virus is likely to be endemic. The need is to focus on vaccination and limit transmission.
• Surveys: The last serological survey by the Indian Council of Medical Research (ICMR) had shown from a representative sample of the population — 70 districts out of 718 — that roughly two-thirds of the population have antibodies. Again, out of those two-thirds, some would have had the antibodies because they have now been fully vaccinated. However, since vaccination rates are still fairly low, the general assumption is that most people who have antibodies have been infected but not all have had disease. This means a majority will be protected from symptomatic disease later on, and they may get infected but are protected. (assuming the virus is not going to change to a form that transmits easily and evades immunity)
• Life of antibodies: Most people now have antibodies that likely reduces the chance of infection and even if infected may not develop severe disease. This virus is going to stay with us, and society may already have developed herd immunity, which indicates that most have antibodies — either due to infection or vaccination.

1. Countrywide serosurveys indicate almost 67 % Indians, including a large proportion of children, have IgG antibodies.
2. As the antibody levels wane over time, the immunity persists due to memory and T cells. A much larger proportion beyond this 67 % have encountered the virus and would have had immunity due to natural infection.

• Additional vaccine dose: Whether or not a booster dose of a vaccine is required, depends on how quickly the antibody level comes down in the average individual. There are wide variations in the trend of waning of antibody level among persons; sufficient data have not yet accumulated to definitively determine the need.
• Road ahead: One can expect a more or less constant level of infection within the population, with the likelihood of severe illness, hospitalisation or death becoming increasingly small as people are vaccinated. The Delta variant now dominates new infections around the country. Viruses mutate constantly, but whether a new variant will come along that is much more transmissible than Delta and can evade a immune response from either a prior infection or vaccination, remains to be seen. If it does not, then a small background of reinfections and vaccine breakthroughs will help maintain numbers of infected at a low, constant level.
• EXAM QUESTIONS: (1) Explain how the Covid-19 disease may become an endemic in India, gradually. (2) What can a new, deadlier variant of Covid-19 virus do to the world? Explain stepwise? (3) What is immune escape? Explain

#Covid #Mutations #Endemic #pandemic #vaccines

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