  COVID-19--a viral infectious disease--has quickly emerged as a global
pandemic infecting millions of people with a significant number of deaths
across the globe. The symptoms of this disease vary widely. Depending on the
symptoms an infected person is broadly classified into two categories namely,
asymptomatic and symptomatic. Asymptomatic individuals display mild or no
symptoms but continue to transmit the infection to otherwise healthy
individuals. This particular aspect of asymptomatic infection poses a major
obstacle in managing and controlling the transmission of the infectious
disease. In this paper, we attempt to mathematically model the spread of
COVID-19 in India under various intervention strategies. We consider SEIR type
epidemiological models, incorporated with India specific social contact matrix
representing contact structures among different age groups of the population.
Impact of various factors such as presence of asymptotic individuals, lockdown
strategies, social distancing practices, quarantine, and hospitalization on the
disease transmission is extensively studied. Numerical simulation of our model
is matched with the real COVID-19 data of India till May 15, 2020 for the
purpose of estimating the model parameters. Our model with zone-wise lockdown
is seen to give a decent prediction for July 20, 2020.
