'Many say Covid-19 will transition ‘from epidemic to endemic’. But what does this mean?'

[Sukla Sen]

Quite a good explanation, as it appears.

<<Roughly speaking, a disease is endemic in some region if it occurs at a fairly steady level without dying away and without major flare-ups. There may be some fluctuations and seasonal variations but not large surges, namely epidemics. For example, there are four endemic human coronaviruses which tend to circulate more widely in winter, and cause symptoms of the common cold. Could SARS-CoV-2, the virus which causes Covid-19, eventually join them?

There are several common misconceptions which become apparent in discussions of Covid-19 and endemicity.

*It is sometimes assumed, wrongly, that endemic must imply low-level. This need not be the case, although alternative terms such as “hyperendemic” are sometimes used to describe diseases which persist at high levels.

*Low and/or steady cases for a few months do not automatically imply endemicity. If cases are steady for some time, we need to consider why and whether the situation is stable in a long term sense.

*Endemicity need not imply that there are no efforts to control the disease. For example, malaria is endemic in many parts of the world, despite efforts to control it in these areas.

*It may be the most likely possibility, but it is not yet certain that endemicity is the future of Covid-19 everywhere.

Since we still do not have a good idea of what burden of disease to expect if SARS-CoV-2 becomes endemic, it doesn’t really make sense to celebrate this possibility. Of course if there comes a point when the pandemic can be declared over, that will be good news.

Is there disagreement about the future of Covid-19?

As early as May 2020, Michael Ryan, executive director of the World Health Organisation’s Health Emergencies Programme suggested that SARS-CoV-2 might eventually become endemic. In a survey by the journal Nature, reported in early 2021, the scientists polled nearly all agreed that the virus is likely or very likely to become endemic in at least some regions of the world. The majority felt that elimination from even some regions is unlikely.

Certainly, there is broad consensus that eradication of the virus is looking unlikely. There are also other possibilities different from either eradication or endemicity everywhere: for example, some regions might see low levels of disease most of the time with occasional major epidemics, a situation which is harder to predict and control.

Why does eradication seem unlikely at the moment?

The answer lies in the ease with which the disease spreads, and the nature of the immunity we acquire after infection or vaccination.

Crucial to the eradication of smallpox was the fact that vaccines provide effective long-lasting protection against infection. Covid-19 vaccines, on the other hand, provide highly effective and probably long lasting protection against severe disease; but protection against infection is imperfect and wanes more quickly. The same is likely true for the immunity we get after natural infection – it provides some protection against reinfection, but probably stronger protection against severe disease.

Based on current knowledge, it seems unlikely that many places could drive transmission down to zero and keep it there. Even if some region does achieve elimination for a while, the question is whether it will be able to keep the virus out forever in an interconnected world.>>

(Excerpted from: <https://scroll.in/pulse/1007845/many-say-covid-19-will-transition-from-epidemic-to-endemic-but-what-does-this-mean>.)