Resurgence of COVID 19 in India – what does it mean?

The Hindu

14 hours ago

The SARS-Co-V2 that caused the COVID-19 pandemic did immeasurable harm to the world's population, socially, economically, psychologically. The pandemic continued in waves for about 3 years -- each wave driven by a different variant of the virus.
Covid phases and health impact
The first wave in 2020 was caused by the Wuhan virus that caused serious disease with hypoxia, clotting/bleeding problems and relatively moderate mortality. In India it started in March-April, peaked in September and abated by January 2021.
The second wave in 2021 was caused by the Delta variant that spread far more rapidly, producing an even more serious disease. It started in February, peaked in April and retuned to baseline by June. During those months it outran the health services and caused the greatest loss of life.
Memories of our experience, falling ill or watching family members or friends getting admitted in Intensive Care Units in hospitals, our elders dying in isolation, the agonising choice to take or not to take vaccine and which vaccine, lockdowns and school closures etc are still in our minds if not in the conscious level, certainly in the subconscious. Those nightmare memories are being brought forth in recent days, with the news of a resurgence of COVID-19. Electronic media keep reporting the resurgence on a daily basis, as if another wave is imminent. Truth is, no wave can occur, as we analyse the past.
The third wave was caused by the Omicron variant. It started in January 2022, peaked in February and abated in March. The pandemic ended in mid-2022, and thereafter the SARS-CoV-2, exclusively the Omicron variant, has remained everywhere in the world as 'endemic' meaning thereby: continuing and constant transmission in very small numbers. We have one more disease-causing virus in circulation than pre-pandemic. Most of us have forgotten the mildness of the third wave disease. The current resurgence is caused by the Omicron sub-variants -- and the anxiety during the first two waves is no longer necessary.
Variants and disease patterns
Incessant mutations are a feature of SARS-CoV-2. Most resultant variants are of no consequence but of curiosity for the molecular virologists. Some variants, as indicated by the missing alphabets (Greek) were of public health interest but not of concern. Three variants of Wuhan original – Beta, Delta and Omicron were of concern. The variants of concern had higher transmissibility and the ability to evade immunity than their predecessors that lost out in competition. Thus, Delta eliminated previous variants, and Omicron eliminated the Delta variant.
Infectiousness or transmissibility, can be measured. The average number of individuals infected by one infected person is denoted as the 'reproduction number' R. The higher the R, the more infectious the variant, and the faster and greater its spread. The original Wuhan variant had R of ~ 2, Delta had R of ~ 4, Omicron variant had R of ~ 8. The JN1 sub-variant of Omicron is said to have R of ~12 . The current NB.1.8.1 and XFG sub-variants must have even higher R value.
Between Delta and Omicron, there was a drastic change in disease pattern. Delta caused the classic COVID-19 in its worst form. The Omicron is much more mutated than the previous variants – think of it more as 'deviant' than variant, for two reasons: one, the unusually large number of mutations on the spike protein gene and second, its disease is just like a sore throat or upper respiratory tract disease.
The Omicron disease spares the lungs. It does not cause hypoxia, or bleeding/clotting disorders. It does not cause loss of smell – which is due to virus invasion of the smell apparatus, olfactory bulb. The biologic reason for the deviant behaviour is that Omicron's cell entry process is distinctly different from all other variants. Omicron infection does not cause fusion between adjacent cells – in technical terms syncytium formation.
Despite all these advantages, the virus is the same species and all the above are in relative terms. Even immunity evasion is only partial – any immunity from previous variants certainly makes the subsequent infection less severe. However, those with severe co-morbidities or old age with immune senescence or immunosuppression due to any disease or disease treatment can develop severe complications affecting several body organs and may require hospitalisation and even intensive care. For them, mortality can be high. But counting their deaths does not reflect the reality of virtually no mortality in healthy population.
Omicron also undergoes restless mutations, all denoted by English alphabets and numerals – they are mistakenly called variants by many, while they are all sub-variants. The currently highly prevalent subvariants including NB 1.8.1 and XFG (which is a recombinant of two earlier subvariants) are all derived from Omicron JN.1 sub-variant, and all the clinical features described for Omicron infection above are valid for all of them.
Drop in testing and the false sense of security
By August 2024 many countries stopped testing routinely for SARS-CoV-2 infection. That gave the false impression that the virus had stopped circulating. What happened recently, was that the countries that had continued testing reported the increasing trend of virus circulation, following which we also began testing – the more we tested, the more we found.
New-born infants, about 70,000 per day in India, adding up as annual birth cohorts constitute the immunity-naïve population pool for driving the continued virus circulation. But we know next to nothing about the frequency of infections in them.
Re-infection despite immunity is the norm for SARS-CoV-2. Omicron and its sub-variants became progressively more infective and had greater potential for spread. The recent number of COVID-19, reported as nearly 7,000, reflects the greater volume of testing, not the true magnitude of infection or disease in the population.
The Ministry of Health is monitoring the situation and has advised testing only for patients with influenza like illness (ILI) and patients admitted with severe acute respiratory illness (SARI). Because testing is selective, the reported numbers reflect more of those with significant symptoms than the true numbers of those with mild disease.
Immune escape
It is of note that successive variants of the virus have clearly demonstrated the 'immune escape' phenomenon. This immune escape is partly because immunity from previous infection and from previous vaccination wanes with time. Greater infectiousness is also due to the property of 'immune evasion' by the more successful variants and sub-variants. During the 2022 Omicron wave, most new infections were in those who had immunity from past infections or immunisation or both.
What is the likely outcome of this upsurge in cases?
The vast majority of those infected will have mild illness like a sore throat, dry cough (since lungs are not involved), fever, headache, etc. Some get mild diarrhoea too. By virtue of previous infection and or immunisation even the elderly and immunocompromised individuals also will mostly have a mild illness. A few individuals will develop pneumonia and will need hospital admission and out of these a small number will succumb. Management of these individuals should be along established lines with supportive treatment and steroids. Antiviral drugs are unlikely to be of much help.
As in all endemic viral infections, every upsurge will also peak and then decline after which the community will fall back into the steady state of endemic prevalence. What was surprising was the upsurge during high summer and very hot days. Most other respiratory viruses are more active during cooler times and rainy season.
The elderly and the immunocompromised individuals are well-advised to wear masks when they have to be in crowded places and during travel by bus, train or aeroplane. This precaution is necessary even at home if another family member has upper respiratory symptoms.
(Dr. M.S. Seshadri, is a retired professor of the department of endocrinology, diabetes and metabolism, Christian Medical College, Vellore. Email: [e-mail] Dr. T. Jacob John, is a retired professor of clinical virology, Christian Medical College, Vellore. Email: [e-mail])