The total vaccine doses administered in the country crossed 99.7 crore on Wednesday, according to the 10.50 pm data from the CoWIN portal, with around 75 per cent of all adults having administered the first dose and around 31 per cent having received both doses.

Union Health Minister Mansukh Mandaviya appealed to all those who are eligible to get inoculated without delay and contribute to the “historic” journey. He will launch a song by singer Kailash Kher and an audio-visual film at the Red Fort for the occasion. The day is also expected to see the raising of the largest national flag, weighing around 1,400 kg, at the Red Fort, news agency PTI reported.

The government had also planned to make announcements over loudspeakers on trains, planes, and ships. It has also said that villages that have completed 100 per cent vaccination should mark the 100 crore-doses administered achievement by putting up posters and banners complimenting health workers for their role in the exercise.

RS Sharma, CEO, National Health Authority, told NDTV on Wednesday, “We are doing 700 vaccinations per second. It will be a little difficult to find out who will be the ‘100 croreth’ beneficiary.”

Sources said BJP leaders have been asked to visit vaccination centres; party chief JP Nadda will be in Ghaziabad in UP, which votes early next year, for the occasion, while General Secretaries Arun Singh and Dushyant Gautam will be in Tamil Nadu’s Coimbatore and Lucknow, respectively.

The administering of one billion vaccine doses – given the unknown and unpredictable nature of the coronavirus, the scale and intensity of the pandemic, and the challenges surrounding manufacturing, distribution, and delivery – represents a significant effort on the part of the government. Only one other country has administered over a billion vaccine doses – China (crossed 1 billion doses in June), which is also the only other country to have a population of more than one billion.

Last month the Centre – to celebrate Prime Minister Narendra Modi’s 71st birthday – administered over 2.5 crore doses in a day; that was the fourth time over one crore doses were given in a day. Following that, however, concerns were raised over the actual number of shots given, after some shocking discrepancies emerged from Madhya Pradesh, including jabs being given to dead people.

However, many including the opposition Left parties have pointed to a possible red flag – the discrepancy between the number of fully vaccinated individuals and those with just one shot. Only an estimated 20 per cent of the country’s 1.4 billion people have received both shots. By contrast with the country’s busiest festive season, an estimated 51 per cent have been given just one dose so far, which gives an estimated 30 to 50 per cent protection against the virus.

The government has said a “sizeable number of eligible beneficiaries” have not taken their second dose, but it has declined to share the numbers. In Telangana, however, an estimated 25 lakh beneficiaries who had their first dose in June/July have missed the deadline for the second.

The disparity between the partially and fully vaccinated is among the highest in the world, and of concern to a country that has already reported over 450,000, or 4.52 lakh, deaths. The government is aware of this problem and has called on states and union territories to focus on administering the second doses, and advised them to share strategies to close the gap.