COVID-19 IN INDIA : Waves , Variants of Concern , Airborne Transmission :-
The novel coronavirus disease caused by SARS-CoV-2 in 2021, is a tsunami like coronavirus outbreak relative to the previous outbreaks involving older coronavirus or Swine flu (HINI) or Spanish flu. with the number of COVID-19 cases now exploding worldwide, it is certain that transmission of SARE-CoV-2 is very high possibly airborne (aerosol droplet ) and there are diverse spectrum of disease severity . The biological issues like a genetic susceptibility and variability in the response to the virus are still being elucidated . Controlling current rates of infection and combating future waves require a better understanding of the require a better understanding of the routes of exposure to SARE-CoV-2 and the underlying genomic susceptibility to the disease .
The second surge in India started very quietly from less exposed population clusters in some districts from where it's rapidly spread to rest of India . Clearly in the second wave we are seeing a faster transmissible strain , but of unknown virulence. Currently the Indian variants of concern are being investigated by genome and public health experts to delineate if it's an imported strain like UK , South African or Brazilian one or is a home grown mutant .
Vaccine is the fourth pillar after the covid-19 appropriate behaviour of mask , distancing and sanitizing . The vaccine primary goal is to protect the most vulnerable from death and severe diseases . These are all early generation rapidly developed vaccines which are all in Emergency use authorisation (EUA) mode . India is part of the global alliance for vaccine nationalism by exporting vaccine fulfilling its global obligations . We need to vaccinate all our vulnerable groups which can succumb to COVID-19 independent of the age but must follow vaccine discipline . Even after vaccination with full doses we need to mask , avoid crowds or poorly ventilated spaces , distance and sanitize .
The detection of SARS CoV2 in air both in indoor and outdoor spaces is now better understood and linked to virus viability in air ; factoring both temperature and humidity . The northern hemispheric , temperate regional waves in winters and the tropical India wave in hotter , humid environments merits scientific scrutiny.
The different types of vaccines
There are three main approaches to designing a vaccine. Their differences lie in whether they use a whole virus or bacterium; just the parts of the germ that triggers the immune system; or just the genetic material that provides the instructions for making specific proteins and not the whole virus.
Inactivated vaccine
The first way to make a vaccine is to take the disease-carrying virus or bacterium, or one very similar to it, and inactivate or kill it using chemicals, heat or radiation. This approach uses technology that’s been proven to work in people – this is the way the flu and polio vaccines are made – and vaccines can be manufactured on a reasonable scale.
However, it requires special laboratory facilities to grow the virus or bacterium safely, can have a relatively long production time, and will likely require two or three doses to be administered.
Live-attenuated vaccine
A live-attenuated vaccine uses a living but weakened version of the virus or one that’s very similar. The measles, mumps and rubella (MMR) vaccine and the chickenpox and shingles vaccine are examples of this type of vaccine. This approach uses similar technology to the inactivated vaccine and can be manufactured at scale. However, vaccines like this may not be suitable for people with compromised immune systems.
Viral vector vaccine
This type of vaccine uses a safe virus to deliver specific sub-parts – called proteins – of the germ of interest so that it can trigger an immune response without causing disease. To do this, the instructions for making particular parts of the pathogen of interest are inserted into a safe virus. The safe virus then serves as a platform or vector to deliver the protein into the body. The protein triggers the immune response. The Ebola vaccine is a viral vector vaccine and this type can be developed rapidly.
The genetic approach (nucleic acid vaccine)
Unlike vaccine approaches that use either a weakened or dead whole microbe or parts of one, a nucleic acid vaccine just uses a section of genetic material that provides the instructions for specific proteins, not the whole microbe. DNA and RNA are the instructions our cells use to make proteins. In our cells, DNA is first turned into messenger RNA, which is then used as the blueprint to make specific proteins.
A nucleic acid vaccine delivers a specific set of instructions to our cells, either as DNA or mRNA, for them to make the specific protein that we want our immune system to recognize and respond to.
The nucleic acid approach is a new way of developing vaccines. Before the COVID-19 pandemic, none had yet been through the full approvals process for use in humans, though some DNA vaccines, including for particular cancers, were undergoing human trials. Because of the pandemic, research in this area has progressed very fast and some mRNA vaccines for COVID-19 are getting emergency use authorization, which means they can now be given to people beyond using them only in clinical trials.
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