Emphasising that vaccines, which have been approved for restricted use Dr Samiran Panda, Head, Division of Epidemiology; Communicable Diseases (ICMR) and member, national expert group on Covid vaccine administration, in conversation with The New Indian Express said recruitment of greater number of participants is necessary for examinations of the shots.
Q. As the Covid-19 vaccination program has begun, there seems to be some vaccine hesitancy among healthcare workers. How seriously is that being taken?
Healthcare workers are more susceptible to infection due to the nature of their occupation and if we compromise on their health it will adversely impact upon the entire healthcare system. They are also prone to re-infection. Therefore, it is right to consider them under priority groups for vaccination. Such an approach will not only protect them and through them their families, but also those who need their care. I would like to emphasize here that the vaccines, which have been approved for restricted use, are safe, and they are also immunogenic. Healthcare workers therefore need not be afraid of taking it. However, as anybody else, they will weigh the pros and cons, and will think whether to take or not to take avaccine because the disease is new and the science around COVID-19 is yet evolving. The decision to take or not to take a vaccine is an individual choice. Hesitancy is normal but overcoming it is superlative. There are direct as well as indirect benefits of a vaccination program. The impact of vaccination crosses the boundaries of an individual, and reaches out to familial and societal level particularly when a critical mass in a society gets vaccinated.
Q. There is some confusion on the efficacy of Covishield (the Serum Institute of India itself has shared varied efficacy numbers on the package insert) and phase 3 trials for Covaxin are still underway. Many feel that the regulatory approvals to the two vaccines were rushed. Though senior authorities, including you, have been insisting that people should not “doubt” the approvals, there is a concern that enough confidence building measures have not been taken. Your views?
Innovative regulatory measures, such as restricted use in an emergency situation, are the need of the hour. We are in the midst of a pandemic and we may need to take some extraordinary measures to navigate through this extraordinary time. Not only in India, but scientists all across the globe worked hard to make vaccines against COVID-19 within such a short span.
The Covishield package insert presents different time gaps between administrations of the two doses of the vaccine in a tabular form next to the respective efficacy data. Subgroup analysis is also presented showing higher efficacy of the vaccine with greater time interval of administration; over 70 percent when the gap is 12 weeks, whereas the efficacy was a little over 50 percent when the two shots of the vaccine are administered with an interval of 4-6 weeks. To establish such differences, one needs to examine these issues with recruitment of greater number of participants.
Here I would like to highlight an issue. In a pandemic of this nature, such as COVID-19, one preferably would not wait for 12 weeks to administer two doses of a vaccine because one, many things change over a period of three months including the disease transmission dynamics. Second, people may forget to take the second dose. Third, people may need to move to some other place for whatever reason. Therefore, the quicker avaccination schedule is completed for an individual in such situations – the better it is.
If all else remain equal around vaccine related considerations – such as production capability, supply, storage facility, cold chain logistics, cost etc - a single shot vaccine, if available, will always be preferred, from an outbreak prevention perspective compared to a vaccine that requires multiple shots.
Q. The restricted emergency use authorization granted to Covaxin says that it will be used in “clinical trial mode.” To begin with the government has procured 55 million doses of the vaccine. Does it mean that all those who receive the vaccine will be actively followed up? Has a mechanism for such an experimental roll-out been put in place?
First, ‘clinical trial mode’ is not a clinical trial and under such a modality, comparisons are not aimed at. In a clinical trial mode, the recipient of a vaccine is monitored with a greater rigor once she/he opts in for administration of the vaccine in concern. While the phase-III trial is ongoing, Covaxin has been concurrently made available for restricted use in emergency situation.
As I understand, preclinical studies, results of the phase I clinical trial as well as data generated on immunogenicity of the vaccine from phase II human trial read with the provisions under the new drugs and clinical trial rules paved the path for restricted use in emergency situation. Given the situation we are in, I see it as an important and necessary move from public health perspective.
Q. Many epidemiologists also believe that a considerable amount of herd immunity, at least in urban parts of the country may already have set in—and it is supported by a falling number of cases and deaths. Do you think the majority of the country would still need shots against Covid-19 before the pandemic is under control?
Yes - the COVID epidemic curve is on a decline but we must also remember that India is a huge country and heterogeneity exists between the states in terms of disease transmission dynamics. There are states where the second and third waves of the infection have been noticed. Also, there are states with case fatality rate above the national average.
Moreover, new mutants are making their appearances and we are yet to understand their behavior fully. It is also important to notice that while surveys in a few pockets in urban India revealed a prevalence of infection- exposure (reflected through positive antibody test) to the tune of 20% - 30%, the second round of national serosurvey conducted during August through September, 2020 recorded a seroprevalence of 7 percent from a nationally representative population-based sample. Although, some were of the opinion then that India as a country was close to herd immunity, the data from national serosurvey did not lend support to such assertion. It is not surprising that cities with high population density and less Covid-appropriate behavior in public life recorded higher antibody prevalence.
However, such isolated surveys were inadequate to capture the national scenario. It would be worth noting here – I guess – that herd immunity is achieved during the natural course of an infection when 70% to 80% of the people in a community or country gets exposed and infected.
Q. A number of trial participants in Bhopal, enrolled for phase 3 clinical trial of Covaxin in People’s medical college have levelled serious charges on the conduct of the trial. One of the participants had also died even though it has been clarified that it may have nothing to do with vaccination. The government and the regulator however have not even acknowledged the issue. Your thoughts?
I am aware that the death, you have been talking about, has been reported to the concerned institutions as per trial protocol as the deceased individual was one of the trial participants. However, in my knowledge, the causal link of the death did not get established with the investigational product – the vaccine. Although any death is unfortunate, they do not necessarily take place due to vaccines, particularly when they occur among trial participants.