Covid-19 will eventually reach endemicity - A scientific look

Eventually, Covid-19 is bound to reach endemicity across nations, but the path to that is troublesome.

 Covid-19 will eventually reach endemicity - A scientific look

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• Await for Winter 2025: It is likely that winter 2025 would be normal, with lot of patients suffering from influenza landing up in hospitals. Perpahs a new seasonal disease - Covid-19 - too will arrived, hitting the elderly. But life will continue normally outside hospitals.
• Pandemics: Many pandemics have happened in past 120 years, with a huge death toll. Covid-19 has killed more than 1.5 crore so far, at least, as per the excess deaths model. It is not the deadliest disease, but is new, and is everywhere.
• Buring out: But all pandemic burn themselves out eventually. Large no. of people develop immunity, so viruses can't find new hosts fast enough. But only smallpox was ever totally eradicated. Influeza, measles, cholera have continued as endemics. Covid will be no different.
• Not possible to eradicate: Other than China, all countries now accept eradicating Covid is not possible. Most nations did not fight as hard as was needed. The extremely transmissible Delta variant made this eradication thing more difficult. Hence, more lockdowns and more quarantines. Even China's zero Covid strategy will not last long.
• Endemicity: It means that a virus circulates at a fixed speed, with minor variations, but does not disappear or overwhelm. Infections reach an equilibrium, where proportion of population becoming susceptible is in balance with likelihood of transmission. Vaccines can push that equilibrium point lower.
• Polio and measles: These two were eradicated finally, and were once endemic. The motivation to eradicate was that these hit children. With Covid, children are less at risk, and vaccinated people are able to catch Covid and pass it on. Common cold can be caused by around 200 different viruses, and no one gets seriously ill. Colds are endemic.
• Influenza: It kills 5 lakh annually (average) mostly the old. Vaccines are given annually, but it persists. Virus keeps mutating fast. Covid Delta variant reproduces twice as fast as H3N2, the most common flu strain. Finally, one day, flu and Covid may kill approx. 50000 and 100000 per annum, in America. But today, things are not under control in Covid, in many parts of the world.
• What decides endemicity: Three things

1. What proportion of given population will be immune, and the quality and durability of that immunity
2. How the disease gets treated
3. How the virus evolves

• Immunity is complex: No one understands immune system fully. Both Quality and quantity of antibodies made, matters. Slowly better antibodies - in terms of sticking to the spikes - evolve. Individuals with higher antibody levels may also catch Covid, but at a population level, high level of neutralising antibodies means fewer infections. Vaccines have given humanity a shortcut to immunity, which otherwise would have cost heavily. More than 50% humanity today has some form of immunity to Covid-19.
• Rich and Poor: Majority of the poor people in this world are getting immune due to infections, not vaccines. In coming years, a slow decline in Covid will happen, as immunity through infections spreads. One day, Covid will be a disease mankind will live with, thanks to vaccines and better treatments. Many new anti-virals are under development now.
• Next variant: Any new virus variant is likely to be based on Delta, as it has displaced all others for now. Beta variant used to defeat immunity better than Delta, but was driven out by Delta (that spread faster). If a new variant combines these two traits - higher spread and better at beating immunity - it would be bad. Delta Plus failed to take off, but a new Delta with Beta characteristics may emerge.
• EXAM QUESTIONS: (1) Explain the concepts of endemicity and immunity. (2) What do you expect in 2025, as far as the Covid pandemic is concerned? Explain. (3) Explain the major turning points in the Covid-19 pandemic, so far.

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