How effective is our COVID vaccine against the Delta variant?

Chairman of India’s COVID-19 Working Group of the National Technical Advisory Group on Immunisation (NTAGI), Dr N K Arora, spoke to DD News, on India’s COVID-19 Vaccination Drive.

Q. Will, there be a third wave of COVID-19 in India?  

Almost 30,000 – 45000 daily cases on average are being reported in our country for the last several weeks. This is reported mostly from specific geographic regions, especially Kerala, many North Eastern States and a few districts of Maharashtra and some other southern states. If we follow the genomic analysis of SARS-COV-2 viruses circulating during June, July and August, no new variants have emerged and based on serosurvey conducted during July, the ongoing COVID cases represent the susceptible individuals who are not yet immunized; they are affected as part of the last phase of the second wave.

In the serosurvey of July, 66% to 70% of people were found to be infected; this also means 30% of people are still prone to infection; and that they can be infected any time particularly if they are still unvaccinated. Hence any complacency on the part of any of us throughout the country will cost hugely since 30% of people can be infected and many of them can develop severe disease and rarely fatal, as we witnessed during April and May 2021.

Hence, following COVID Appropriate Behaviours is essential and critical, especially with the coming festive season. The emergence of new mutations around this time can also be a reason for the arrival of a third wave.

Q. How effective is our COVID vaccine against the Delta variant? What should we do to prevent a third wave?

The effectiveness of COVID vaccines can be explained in the following manner:

• Effectiveness in the prevention of infection and thus the spread of the virus
• Effectiveness to prevent symptomatic disease
• Effectiveness to protect from severe disease or death

The effectiveness values we see in media mostly refer to the effectiveness against symptomatic disease; it is generally 60-90% for different vaccines.

Most of the vaccines are not adequately effective in preventing COVID infection and therefore, it is repeatedly emphasized that even after vaccination, the person can spread COVID infection and need for maintaining COVID appropriate behaviour.

The most important value of the COVID-19 vaccines is their effectiveness to prevent severe disease, need for hospitalization and death. All the vaccines currently available in India and elsewhere are over 90-95% effective for protecting the beneficiary from severe disease and death. This is true for all the variants including the delta virus. Most of the infection occurring in India today is due to Delta virus.

Q. If someone was infected with COVID-19 and now there are antibodies in his/her body against COVID-19, then can he/she donate blood or plasma to someone who is now infected with COVID-19? High-quality research in our country under ICMR revealed that plasma therapy was not useful for most patients with severe COVID infection requiring hospitalization. Similar studies from other parts of the world have similarly failed to prevent death or reduction in the hospital stay. It for these reasons, the ICMR has removed plasma therapy as part of the treatment guidelines for severe COVID-19 infection.

Having said that, if someone is infected, there will be the generation of antibodies in his/her body along with cell-based immunity. Antibodies are measurable and can also be called visible immunity. The cell-based immunity can also be termed invisible immunity and is as important as antibodies. These immunity components prevent disease and severity when such a person gets re-infection with COVID 19.

Recently an antibody mixture was introduced in the market by a company, but that did not show much benefit. This antibody mixture also was based on the principle of plasma therapy. It was observed that if plasma or antibody is given to the patient in the first week or early part of the infection, then there can be some benefit.

A paper published recently mentions that if someone has got a natural COVID infection and has recovered, then the immunity of that person will protect him for a long duration and in case if such person also takes vaccine, then the individual has double-barrelled protection against infection and the disease.

Is there a need for a booster dose of vaccine for our people?

The requirement of a booster dose in our country cannot be decided based on the situation and decisions taken in western countries. Local evidence based on the studies done in different parts of the country will guide the need for our people. This will be considered in the context when 70% to 80% of the population in our country is already infected. Overall a considerate decision will be taken based on the best available scientific evidence with the overall objective to provide optimal protection to our people.

Q. Should we see the efficacy of vaccines and limitations of an individual’s body hand in hand or should they be seen differently? Does the infection depend on the limitations of an individual’s body or is the efficacy of the vaccine the same for everyone?

These aspects should be observed in an integrated manner. The response of young individuals to any vaccine including the COVID-19 vaccines is most robust and the vaccines show maximum effectiveness. Increasing age and the presence of co-morbidities might decrease vaccine effectiveness. For this reason, during the initial trials, elders i.e., those above the age of 60 years are included. Fortunately, the COVID-19 vaccines work almost equally in all. These are important issues as the seriousness of disease and risk of death in the elderly and those with co-morbidities is almost 20-25 times more as compared to younger persons and those without any co-morbidities. This was the basis of coming out with a vaccine prioritization list of vaccine recipients. There are disease conditions that severely affect the body’s immune system e.g., cancer patients on treatment, health conditions requiring steroids. The protective response of vaccines in such individuals can be inadequate and might need another dose of the vaccine or booster dose. The NTAGI will be considering these issues while deciding about the need for a booster dose of COVID vaccines.