New Delhi,  India's Covid-19 vaccination coverage has crossed the 85 crore mark, but the success of this mass drive against the pandemic depends on people getting fully vaccinated with both doses, says a leading expert.

In an interview to IANS, Dr Arun Kumar Sharma, Director ICMR-National Institute for Implementation Research in Non-Communicable Diseases (NIIRNCD), Jodhpur, reveals why full vaccination against Covid is important, as well as what to do if you miss a dose.

Following are excerpts from the interview.

Q: Why both doses of the vaccines necessary for protection against Covid infection?

A: For strong protection against Covid infection, it is necessary to have both doses of the vaccine... even after the first dose, the defence system against infection is made, but two doses of vaccines have been approved by experts after intensive research and testing. A strong protective shield against infection can be prepared only after both the phases of vaccination, so the second dose of Covid vaccine must to be administered at the scheduled time.

Q: Does even a single dose provide sufficient protection against infection?

A: Antibodies are partially formed after the first dose of the Covid vaccine. Antibody titre test gives an idea of what percentage of antibodies are made in the body after taking the vaccine. For example, if after taking the first dose of vaccine, 40 per cent of antibodies are formed, then for the remaining 60 per cent of antibodies, we have to take the second dose of vaccine, which will give us 100 percent protection against infection.

Q: If a person misses taking the second dose or if it is too late, then what?

A: Under the prescribed system of Covid vaccination, after taking the first dose, you are informed, through a message, to take the second dose. This message is sent continuously until you take the second dose of the vaccine and your certificate of complete vaccination is ready. Despite this, if someone is not able to take the vaccine even after the prescribed time for the second dose, then on the advice of the specialist, they should get an antibody test. If there are no antibodies, then they should start the sequence of re-immunisation from the first dose.

Q: Does India also need to introduce booster dose of vaccine, as many nations have done?

A: Whether the booster dose should be given or not is still a matter of research. India's vaccination monitoring team is constantly monitoring this topic, and so far no recommendations have been made regarding booster doses in the trials. If it is needed in future, it can be considered.

Q: Is people's negligence towards the second dose a significant challenge in achieving herd immunity?

A: If a large population of any state or region gets vaccinated against Covid, it means that infection will not spread in that pocket, thus the infection chain can be broken, conversely if more and more people are not serious about vaccination, people can be the easier targets for the virus through non-vaccinated people as the virus will continue to get the human body to spread the infection.

In such situation, not only the chain of the infection will be difficult to break, but mutation of the virus also cannot be ruled out.

Q: Does Covid appropriate behaviour need to be followed even after both doses of vaccines are administered?

A: Of course, even after getting both the doses of Covid vaccination, it is necessary to follow the Covid appropriate behaviour. By following Covid appropriate behaviour, we give double protection to ourselves and others against the infection. It is possible that the virus will not affect one having both doses of vaccines, but it can enter the body of someone whose immunity is not as strong as ours or his body does not have antibodies to fight against the infection. So even after taking both doses of vaccine, keep the mask on and follow the prescribed distancing and other norms.