There is an opportunity for progressively easing continued low transmission restrictions, but under vaccination, the use of masks
on 27 June 2021 Daily Reported COVID-19 Cases (the seven-day rolling average) had fallen below 50,000, and is remained like this for 15 consecutive weeks (Worldometer – Corona-India). This marked the end of India’s second wave of the pandemic and marked its transition to an ‘endemic’ state. This fell below 40,000 on September 9, And below 30,000 on 24 September. The trend continues.
population and infection
Refers to stable weekly numbers without spatial large fluctuations. This trend continues to last for fifteen weeks. Kerala, Sikkim, Mizoram and Meghalaya are national endemic states outsiders/exceptions – they have not yet transitioned to the endemic stage (covid19india.org) but their daily case-trends show that they will soon take hold and become endemic. Country-level endemism indicates that the vast majority of the population is already infected and immune, but how large is the majority?
NS 4th ICMR Sero-survey (June-July 2021) showed that by the end of July 67.6% had antibodies – that is, about 950 million. The cumulative COVID-19 cases reported as of the end of July stood at 30,410,577 (3.2% of 950 million). So, the actual infection was ~30 times the number reported. From 1 August to 7 October – 2,219,097 additional cases were recorded, which, by extrapolation, represents 70 million infections, 1,020 million in total, the susceptible population therefore 1,400 – 1,020 = 380 million. The Indian Council of Medical Research (ICMR) found in a second sero-survey that the prevalence of antibodies underestimates the true immune spread, with the first RT-PCR detecting only ~70% of the positive people, so the susceptible pool is very large. may be small. .
Endemic transmission will be maintained by new infections in previously uninfected remains as well as by annual birth clusters of 25 million (low mortality) by new additions to the population and re-infections in those already infected.
The second wave of the pandemic was driven by a delta variant with an original reproduction number (RO) of 6–8. The epidemiological formula (1-1/Ro) is used to calculate the herd immunity threshold (HIT) required to end the epidemic, which is ~87.5% in our estimates. This observation confirms the fact of epidemiological-endemic transition, applying the principle of the triangle.
on jabi
India introduced its COVID-19 vaccines on January 16, 2021, but the pace of vaccination is slow, with 20% receiving two doses (2.2%). So, the major contribution to reaching HIT was the natural transition in two waves. two recent preprints, One from Christian Medical College Hospital Vellore And from another israel indicate that infection-induced immunity provides greater protection than vaccination. Thus, India’s immune population has short-term protection against re-infection and disease. Actually, Re-infection rate in India According to ICMR it was only 4.5%.
India’s COVID-19 containment strategy, which till now addressed pandemic COVID-19, is now to be revised for endemic COVID-19. Two important factors will determine the modifications: senior citizens, co-morbidities/cancer treatments/organ transplants, etc. and pregnant women, who have not been infected in the past or have not yet been vaccinated with two doses, are at serious risk disease, the need for hospitalization, intensive care unit admission and mortality. They should be individually traced and vaccinated.
more than re-infection
Endemic transmission will be driven more by re-infection than by prior infections. a paper in lancet microbe, October 1, Reported durability of immunity against reinfection in coronavirus infection, Outlining the potential for antibody degradation and re-infection over time under endemic conditions. Re-infection is likely to occur three months to 5–1 years after the peak antibody response, averaging 16 months. Therefore, all previously infected but uninfected individuals require at least one dose of the vaccine.
Studies have shown that people who had natural infections may need only one dose of any approved vaccine to stimulate long-lasting immunity, even against reinfection. Careful follow-up study of antibody levels in people who had the infection is urgently needed to determine when such individuals would require a booster dose. Their immune response profile to a single dose of different vaccines also needs to be documented.
Individuals previously uninfected but receiving two-dose vaccines should be given a booster dose of vaccine to provide protection against reinfection. Immunology states that the optimal time interval for a booster dose is six months to one year after the previous dose. We should monitor both the immune response level and the durability after the booster. Such data will guide when another booster may be needed.
Contact tracing, testing and quarantine requirements – so critical during the pandemic outbreak – will now have to be confined to the elderly and vulnerable contacts to facilitate early detection and treatment of COVID-19, rather than all. Our two-dose vaccination coverage must be increased rapidly – the current weekly rate of about 0.6% of the population given a second dose is too slow and must be revised – through intensive information-education-communication and vaccination campaigns.
Vaccination should be targeted at the reopening of all schools and centers of economic activity. The entire workforce (organised, unorganized, self-employed, employed in the travel and tourism industry) in India needs to be targeted for vaccination; This is best done at the workplace with the help of the concerned managements and state health authorities. Thereafter, all social, religious, cultural and recreational gatherings may be permitted.
childhood infection
Childhood infection with coronavirus is mostly mild and self-limiting because of the low density of the ACE2 receptor (portal of cell-entry of the virus) in the respiratory tract of children. Multi-system-inflammatory syndrome, a serious complication encountered in children, is fortunately very rare and treatable. In these circumstances, children are best protected by fully immunizing all school personnel (teachers, non-teaching staff, transport) and all eligible subjects at home, thereby creating a protective covering.
After any vaccines are approved for use in children, (Covaxin and ZyCoV-D may be approved soon), they can be vaccinated—the easiest way forward would be school-based vaccination camps.
Continued endemic transmission is an opportunity to progressively relax restrictions on social contacts, but such a return to normalcy should be under the umbrella of vaccination (as described above) and universal mask use. When endemicity persists for a long period of time, seasonal outbreaks (slight waves) should be predicted – but even those can be prevented by vaccination. Vigilance cannot be lowered until we are sure that no one is at risk of serious COVID-19.
Dr. T. Jacob John is a retired Professor of Clinical Virology, Christian Medical College, Vellore, Tamali Nadu and former President of the Indian Academy of Pediatrics. Dr. MS Seshadri is a retired Professor of Medicine and Clinical Endocrinology at Christian Medical College, Vellore and is presently the Medical Director, Tirumalai Mission Hospital, Ranipet, Tamil Nadu.
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