Using high effective risk of Adult-Senior duo in multigenerational homes to prioritize COVID-19 vaccination

Universal vaccination on an urgent basis is a way of controlling the COVID-19 infections and deaths. Shortages of vaccine supplies and practical deployment rates on the field necessitate prioritization. The global strategy has been to prioritize those with a high personal risk due to their age or comorbidities and those who constitute the essential workforce of the society. Rather than a systematic age-based roll-down, assigning the next priority requires a local strategy based on the vaccine availability, the effectiveness of these specific vaccines, the population size as well as its age-demographics, the scenario of how the pandemic is likely to develop. The Adult (ages 20-60) - Senior (ages over 60) duo from a multigenerational home presents a high-risk demographic, with an estimated "effective age" of an adult living with a grandparent that is not vaccinated to be 40 years more. Our model suggests that strategically vaccinating the Adults from multigenerational homes in India may be effective in saving the lives of around 70,000 to 200,000 of Seniors, under the different epidemiological scenarios possible with or without strict lockdowns.

A steady trickle-down from metro districts and improving epidemic-parameters characterize the increasing COVID-19 cases in India

BackgroundBy mid-September of 2020, the number of daily new infections in India crossed 95, 000. We aimed to characterize the spatio-temporal shifts in the disease burden as the infections rose during the first wave of COVID-19. MethodsWe gathered the publicly available district-level (equivalent of counties) granular data for the 15 April to 31 August 2020 period. We used the epidemiological data from 186 districts with the highest case burden as of August 31, 559, 566 active cases and 2, 715, 656 cumulative infections, and the governing epidemic parameters were estimated by fitting it to a susceptible-asymptomatic-infected-recovered-dead (SAIRD) model. The space-time trends in the case burden and epidemic parameters were analyzed. When the physical proximity of the districts did not explain the spreading patterns, we developed a metric for accessibility of the districts via air and train travel. The districts were categorized as large metro, metro, urban and sub-urban and the spatial shifts in case burden were analyzed. ResultsThe center of the burden of the current-active infections which on May 15 was in the large metro districts with easy international access shifted continuously and smoothly towards districts which could be accessed by domestic airports and by trains. A linear trend-analysis showed a continuous improvement in the governing epidemic parameters consistently across the four categories of districts. The reproduction numbers improved from 1.77 {+/-} 0.58 on May 15 to 1.07 {+/-} 0.13 on August 31 in large metro districts (p-Value of trend 0.0001053); and from 1.58 {+/-} 0.39 on May 15 to 0.94 {+/-} 0.11 on August 31 in sub-urban districts (p-Value of trend 0.0067). The recovery rate per infected person per day improved from 0.0581 {+/-} 0.009 on May 15 to 0.091 {+/-} 0.010 on August 31 in large metro districts (p-Value of trend 0.26 x 10-12); and from 0.059 {+/-} 0.011 on May 15 to 0.100 {+/-} 0.010 on August 31 in sub-urban districts (p-Value of trend 0.12 x 10-16). The death rate of symptomatic individuals which includes the case-fatality-rate as well as the time from symptoms to death, consistently decreased from 0.0025 {+/-} 0.0014 on May 15 to 0.0013 {+/-} 0.0003 on August 31 in large metro districts (p-Value of trend 0.0010); and from 0.0018 {+/-} 0.0008 on May 15 to 0.0014 {+/-} 0.0003 on August 31 in sub-urban districts (p-Value of trend 0.2789). ConclusionsAs the daily infections continued to rise at a national level, the "center" of the pandemic-burden shifted smoothly and predictably towards smaller sized districts in a clear hierarchical fashion of accessibility from an international travel perspective. This observed trend was meant to serve as an alert to re-organize healthcare resources towards remote districts. The geographical spreading patterns continue to be relevant as the second wave of infections began in March 2021 with a center in the mid-range districts. FundingNone

A Very Flat Peak: Exponential growth phase of COVID-19 is mostly followed by a prolonged linear growth phase, not an immediate saturation

Innumerable variants of the susceptible-exposed-infected-recovered (SEIR) model predicted the course of COVID-19 infections for different countries, along with the peaks and the subsequent decline of infections. One thing these models could not have predicted prospectively in January or did not adapt to in the following months is that the peak is rather a plateau for many countries. For example, USA and UK have been persisting at the same high peak of approximately 30,000 and 5,000 daily new infections respectively, for more than a month. Other countries had shorter plateaus of about 3 weeks (6,400 cases in Spain). We establish that this plateau is not an artifact, and the "persistence number" describing the decline needs an equally important attention as the "reproduction number". The solution lies in including the specific epidemiological role of asymptomatics and pre-symptomatics in COVID-19 transmission, different from SARS and influenza. We identify the minimal changes that can be made to any SEIR model to capture this plateau while studying seasonal effects, mitigation strategies, or the second wave of infections etc.