Number of cases came down throughout the nation when we opened up in a phased manner, but when the immunity wanes, we might need booster shot and we must not deny taking it, said Professor Prof Naveet Wig, HOD Internal Medicine, AIIMS, Chief of Delhi Covid Task Force and one of the authors of the Lancet study that recently suggested that Bharat Biotech’s Covaxin was 50% effective among HCWs during the second wave.
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How has common man to interpret the data that has emerged now?
Prof Naveet Wig: We need to understand how vaccine works and how the implementation is done. We conducted the study between 15th April and 15th May 2021, and we were undergoing the peak of second wave at that time and our primary objective was to find out the efficacy of two doses of Covaxin after two weeks. During that time, the efficacy of the vaccine after two weeks of the second dose was 50%, but after 42 days, it increased to 57%. Thus, it can be said that the efficacy of the vaccine increases with time. The efficacy of Pfizer in Israel against Delta variant was 40%, this prompted them to administer booster shots which decreased the number of infections.
Tell us about the details about the subjects on which you tested Covaxin.
Prof Naveet Wig: Layman should be happy that the vaccine is showing as high as 50% efficacy at a time when Delta variant is spreading. Moreover, vaccine is not the only thing, we need to look at what is happening around the world, lockdown has been imposed in several countries once again. Hence, non-pharmacological measures need to continue. Mask is a necessity as it reduces the chance of infection, therefore increasing the efficacy of vaccine.
Would you not say that the study is also indicating the evasive nature of the Delta variant and the waning of the efficacy of the vaccines as the number of weeks passed by?
Prof Naveet Wig: Therefore, now we need to work on the duration of efficacy of these vaccines and when we need to give boosters. We should do real good studies quickly as we need answers. When boosters were given in Israel, the efficacy of the vaccines was increased to 93% after 7 days of the third dose, but it was an mRNA vaccine, while Covaxin gives a broad immune response. Antibody levels with Covaxin and Covishield start falling after 6 months, but again T-Cells take care of it. But we must also remember that people above 60 years of age do not have such good immune response system and might as well require the third dose initially.
What is your thought on the booster shot, considering the huge debate going on around it?
Prof Naveet Wig: This is why I say we need to conduct studies in which we show that antibody levels are not sufficient in some individuals and present it to them. We need to go stepwise and first consider the healthcare workers and after that we need to study people above 60 years of age and for this, we have a window of next 1 to 2 months only.
Please elaborate the reason behind such a short duration.
Prof Naveet Wig: I want to say that the immunity for mRNA vaccines came down in America and Israel and people are still getting hospitalized. Israel released the study in July and they started giving boosters in August. We are little delayed, but since our vaccines are broad spectrum, we do have a little more time but we also need to consider immunocompromised people.
Are you suggesting that the government should start rolling out boosters for those who are above 60 and those who are at high risk in a span of 4 to 5 months?
Prof Naveet Wig: Studies can be conducted in a span of 1 month and we must find out what are their immune response and antibody levels in the specific group of individuals, that includes people above 60, immunosuppressed patients and healthcare workers and then we can consider frontline workers and lower age group.
Tell us the number of weeks in which you studied the efficacy of Covaxin and beyond that.
Prof Naveet Wig: Beyond that, we conducted the study for 1 month. At that time, the test positivity rate was very high and the effectiveness was 50% and when the test positivity came down, it was 75%. Today, the test positivity rate in Delhi is 0.6% and most people are vaccinated, while some people have been infected with Covid already. But we need to prevent increase in number of cases and hence effective studies must be done and mix and match studies needs to be done in future.
Many of us have turned lackadaisical when it comes to wearing masks and maintaining social distancing due to decreasing number of cases. What would you like to tell those people?
Prof Naveet Wig: We currently are not aware as to how long the immunity will last and when the immunity is going to wane. We have seen in Israel and USA where they have recommended 3 doses of Pfizer, and these are the evolving signs. We need to be smart and extra careful.
Once a common man interprets data about 50% efficacy of the vaccine without hearing from the experts, would that increase vaccine hesitancy among the people?
Prof Naveet Wig: My urge to people is that please do not go by numbers. We need to vaccinate people and give two doses after which we will definitely achieve good results. If I am a common man, I will take any vaccine since both are safe and efficacious and prevent severe disease and hospitalization. We are safe but we cannot transmit the infection as the virus does not give time once it starts spreading.
Many mainstream media have been reporting that the final study suggests that the shot is less effective than we initially thought. Is that correct?
Prof Naveet Wig: It was the worst phase of a pandemic across the globe when we saw 67% positivity among workers and that is how the idea came into our mind. Today it is less than 1% and the numbers are below 10,000. But the issue remains that we cannot relax.
People raise concerns when it comes to opting which vaccine to go for. What would you say to those people?
Prof Naveet Wig: Both are equally effective. Please take whichever is available and please take second dose. Our numbers have come down when we opened up in a phased manner and vaccination coverage was done very systematically or scientifically. That is how infectivity of virus is less but when the immunity wanes, we cannot say that we do not need boosters. We need to be very careful.
What would be your message to the people as many say Covid is a thing of the past?
Prof Naveet Wig: Covid will remain with us, it will never be eradicated. We need to take vaccines and make sure we wear masks and do not infect others.