People say we have been able to largely contain the virus without a vaccine. Do we really need one?
We have not witnessed a pandemic of this magnitude after Spanish flu of 1918. This virus has extraordinary capability to spread and cause disease. Viruses reach their peak infection rate, then weaken, but can strike again. It is difficult to predict their behaviour. The vaccines will help control virus transmission and help protect people from progressing to severe infection. If we start now, it will take us a couple of years to vaccinate the entire target population in the country. If you look at human history, there has been no other medical intervention like vaccines that has saved millions and millions of lives, starting from smallpox to influenza. In mankind’s history, there has been no other strategy. So people should not give the vaccine a miss.
n Why is getting a drug against a virus so difficult?
Viruses are inherently unstable, neither dead nor living. Many environmental conditions such as radiations, chemicals cause mutations in them. They are stealthy, hijack the host for multiplication and part of the problem is host defence itself, “cytokine storm”(excessive immune reaction). It took our scientists 30-35 years to develop three-four drugs to keep HIV under control. An anti-viral drug molecule may not behave in the same way in a test tube, in animal models and then in the humans. That is why vaccines are so important when we want to tame a virus.
What makes the novel coronavirus so virulent?
This is one question that is baffling the scientists also. We had seen many other viruses of the same family in the past. For example, SARS-1, though very pathogenic, affected 27 countries and caused around 800 deaths. SARS-2 virus is very closely related to the SARS-1 but it is much more transmissible. One finding suggests that it is so because this virus binds with the receptor very strongly, about 10 times stronger.
Will a vaccine work on mutated strains?
There is absolutely no evidence that the vaccine would not neutralise the mutant virus. Vaccines produce polyclonal antibodies, which means they have the ability to neutralise large portions of the protein. When we make vaccine using spike protein, it will neutralise a large portion of spike protein and prevent entry into the cells of the human body. So, mutations here and there of the spike protein will not make a vaccine ineffective. Unless the mutations are massive, it is very unlikely that the vaccine will not work. In some cases, we keep updating the vaccine. For example, vaccine companies update the flu vaccine by adding new strains of the flu virus circulating in the environment in that year, so the vaccine remains effective against the new strains.
We already have two vaccines in India with more on the way. Do we need a basket of vaccines?
For a population this size, it is better to have a basket of vaccines. Most of these vaccines are targeting the spike protein, but all of them are different. Some are inactivated vaccine, then there is the recombinant spike protein as such, and then there are those that express spike protein using adeno – and other vectors, interestingly DNA and mRNA vaccines. This will help us with the adequate supply and act as backup, if new issues come up. Intranasal vaccine worked upon now will go directly to the lungs and it will be easier to use, if it comes out well after trials.
What about vaccine candidates for children?
We need to look at vaccination of children and that would need adequate trials. While children are supposed to be resistant to SARS-CoV- 2, they are carriers of the virus. Now there is a thinking that we need to test kids also. There are also claims that our vaccines protect the aged population.
Is the mRNA (messenger RNA) vaccine the future for India?
If we succeed in developing an mRNA vaccine, which remains stable at 2-8C, it will be a revolution as an mRNA vaccine can be updated very quickly in case of a mutation. Another innovation is self-amplifying mRNA, which multiplies several folds. The mRNA vaccine is made in a cell-free system and does not need a big scale up using bioreactors. That is what makes it so versatile. Pfizer’s and Moderna’s vaccines are all mRNA technology based ones.