Is Covid now endemic in India?
As INDIA gets ready to
face a possible third wave of SARS-CoV-2, World Health Organization (WHO) chief
scientist has said that “India seems to be entering some stage of Covid-19
endemicity where there is low to moderate level transmission”. Earlier this year,
scientists had indicated in a survey carried out by that the SARS-CoV-2 virus
is set to become endemic and would continue to circulate in pockets of the global
population.
Endemic means something that is present all the time. For example, influenza
is endemic, unlike smallpox which has been eradicated.
“Only those pathogens can
be eradicated that don't have animals (another species) as a reservoir. 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.
In the case of 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. 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 as per doctor.
When is SARS-CoV-2 likely to become endemic?
That will depend on how fast it spreads and mutates. There are many variables that have to be considered as per doctor and there is no clear answer regarding when the virus is likely to be endemic. “Instead of getting bogged down on whether the virus has become endemic or not ,the need is to focus on vaccination and limit transmission. It is not possible to predict when the virus is going to be endemic.
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 they may get infected but are protected. “Again, that is assuming the virus is not going to change to a form that transmits easily and evades immunity. One cannot predict if and when the virus mutates in to some-thing where vaccines start failing.
How long can the antibodies be expected to last?
Most everybody now has 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. We may already have developed herd immunity, which indicates that most of us have antibodies — either due to infection or vaccination — and hence if infected we may not develop severe disease.
From its rate of spread and its rate of mutation, many of us indeed expect that this coronavirus will never be eradicated – not just in India, but globally – and will become endemic to stay with you without causing major health problems, since the vast majority would have developed protective anti-bodies.
Too, referred to country wide serosurveys that indicate almost 67 % Indians, including a large proportion of children, have IgG antibodies. “As the antibody levels wane overtime, the immunity persists due to memory and T cells. We can assume that a much larger proportion beyond this 67 % have encountered the virus and would have had immunity due to natural infection. There is a need for more serosurveys for IgG levels to be carried out.
Can an additional vaccine dose help?
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 for a booster dose.“While vaccine effectiveness
does appear to decline overtime, there is still expected to be substantial protection.
It is likely that a third shot or booster might be necessary in the future and in
fact, a regular booster shot, just like for influenza, might be indicated.
Should we would about numbers rising again?
According to doctor one can expect a more or less constant level of infection within the population, with the likely hood 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 the question is whether a new variant will come along that is much more transmissible than Delta and can evade an immune response from either a prior infection or vaccination.
As long as it does not, we might expect that a small background of re-infections and vaccine breakthroughs will help maintain numbers of infected at a low, constant level. It is more likely that there will be a steady level of cases, with some regions, especially of low prior sero-prevalence and low vaccination rates, seeing spikes. It is completely un-likely that we will see case numbers comparable to the second wave.