During the first wave of Covid-19 in India, in April 2020, the Indian Council of Medical Research (ICMR) had estimated that one Covid-infected person could spread the disease to 406 more people in 30 days, if there is no lockdown
Although Omicron is predicted to cause more breakthrough infections, it is "impractical and impossible" that it will infect huge numbers in India, and result in severe disease and death, if proper measures are taken, experts said on Friday.
The new Omicron variant of Coronavirus is touted to be highly transmissible due to the presence of more than 30 mutations on its spike protein, which the virus uses to enter human cells. The variant harbours a high number of mutations in regions of the spike protein that antibodies recognise, potentially dampening their potency.
"Though Omicron has many more mutations, there are many viral surface particles which are not yet mutated. The people who have some kind of immunity towards the viral surface proteins will have more or less some amount of protection against the new Omicron variant as well," Dipu T.S, Clinical Associate Professor, Division of Infectious Diseases, Amrita Hospital, told IANS.
"So, though breakthrough infections are possible, the chances of Omicron infecting huge numbers at a go is impractical and impossible in the best scenario and the curve will have to go up slowly," he added.
During the first wave of Covid-19 in India, in April 2020, the Indian Council of Medical Research (ICMR) had estimated that one Covid-infected person could spread the disease to 406 more people in 30 days, if there is no lockdown.
And, according to a preliminary study by South African researchers released on Thursday, Omicron can increase risk of reinfection by three times as compared to other variants of concern such as Beta and Delta.
The study, published pre-print on medrxiv, which means not peer-reviewed yet, showed that recent reinfections have occurred in individuals whose primary infections occurred across all three waves, with the most having their primary infection in the Delta wave.
Based on these, can we estimate that an Omicron patient can infect even more or up to 1,000-1,200 people, especially when social distancing norms are being flouted in the country?
"This is not an estimation of the current scenario. Because we need to understand that the immunity was practically zero in April 2020, when ICMR came with its random number of 400," Dipu said.
"But as of today, we are dealing with a completely different scenario, where the vaccination has crossed more than 50 per cent of the population. And we are almost two years into this pandemic," he added.
According to Mrinal Sircar, Director and HOD, Pulmonology, Fortis Hospital, Noida, the possibility is that "Omicron will have a milder course in India".
"The larger difference that we need to see here is that a large set of the Indian population has already received the first dose of the vaccine, which was not the case during the Delta variant outbreak," he told IANS.
Besides, there is this natural immunity which comes from being infected with Covid. In October, the ICMR had stated that across India, the seroprevalence is 67 per cent. This means that already 67 per cent had some form of immunity against the Covid-19 virus.
Moreover, "when we say the reinfection is three times more likely, we are comparing it to the original strain. So the chance of breakthrough infections, which has been reported to be 10 per cent in a year's span, can be up to 30 per cent, which, though is a worrying number, will happen over a period of time," Dipu said.
"As per current preliminary evidence available from African countries, the reinfection rate among previously infected or vaccinated individual with Covid-19 is very very low (below 1 per cent)," Harshal R. Salve, Associate Professor at the Centre for Community Medicine, AIIMS, New Delhi, told IANS.
But, "compared to Africa with 5 per cent vaccination coverage, we have much higher coverage and perhaps thanks to the Delta wave have high seropositivity," Sircar said.
But again, these are all based on the preliminary data and it is too early to predict the behaviour of this kind of strain. We need to wait till more data comes on these cases, the health experts noted.
However, for an infection to transmit, there has to be high risk exposure which is "defined as maskless exposure of more than 15 minutes," Dipu said, adding that wearing masks and maintaining social distance will definitely decrease the progression of the disease in the country.
"We need to be vigilant, but not panic. We need to strengthen our surveillance system and increase full dose adult vaccination," Salve said.