The hope held out amid despair by new messenger RNA vaccines

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The hope held out amid despair by new messenger RNA vaccines

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• A new health science arrives: In the battle against Covid, the power of science is now visible in the battle against Covid-19. The genetic sequence of SARs-CoV-2 virus was deciphered in Feb 2020, and hundreds of vaccines are under development worldwide.
• Origin of 'vaccine': The term comes from Latin 'vacca' meaning cow. Edward Jenner (late 18th c.) had used the cowpox virus as a live source to inoculate humans against deadly smallpox. The milder form of virus was used in cowpox, and it was what later became LAV - Live Attenuated Vaccines.
• LAVs today: They are used to vaccinate against TB, rotavirus, yellow fever, measles and mumps. 

1. The trouble with "virus cultures" led to scientists trying out part of virus (or bacteria) that are not "alive". That led to IVs - Inactivated Vaccines (used for some influenzas and rabies). 
2. Then came the AVs - acellular vaccines - focusing on the proteins that coat the pathogen. Since human bodies recognise these as foreign, the immune system response is triggered. 
3. AVs can be AV-T or AV-PA - AV Toxoid or AV Purified Antigen depending on the response being to the toxic substance the proteins use to attack the body with, or the reaction to the concentrated version of protein.
4. AV-T are used against tetanus and diphtheria, and AV-PA against pneumococcal infections.
5. PA also use an adjuvant (pharma additive to enhance immune response, and use only pieces of the germ so the immune response is targeted to a key part of the germ (so patients with weak immunity too are safe). Booster doses are needed as they are so frugal in character.

• Tough making vaccines: Years of research are needed to get results, efficacy and safety. [Results - whether it works or not, Efficacy - how effectively it works, Safety - what about ill-effects]. More than 25 vaccines are in use worldwide today, but there are no vaccines for many diseases like HIV, Zika, West Nile, Hepatitis C, etc. 
• Covid-19 vaccines: China's Sinopharm made the BBIBP-CorV vaccine (a two-shot inactivated vaccine) using aluminium hydroxide as adjuvant. The Oxford-AstraZeneca vaccine (mfd. for India by SII Pune) is an inactive adenovirus type vaccine. But the future of vaccines has now arrived, in two ways.
• Pathways to future: Some amazing things happened in 2020 -

1. The pathogen's genome is now published rapidly, leading to rapid start to vaccine development.
2. The first-ever mRNA vaccines were ready in 2020 in a few months! (Moderna's mRNA-1273, Pfizer-BioN-Tech's BNT162b2).
3. The m in mRNA is "messenger" and mRNA are the molecular carriers that send genetic instructions. So mRNA teaches human cells to make a protein similar to the virus's and then trigger the human immune response.
4. So the trick is to use mRNA to cut the time taken for vaccine development - we can teach the human body to make proteins similar to that found on the virus, so that immune system may be triggered.

• A whole new world: Now there is no hit-or-miss vaccine development, as the mRNA technique is a genetic engineering process. mRNA vaccines are safe as they do not integrate into human genome, and simply disintegrate over time. Moderna got it first (in 2020) as it had experience of this technique with the MERs virus. The future is bright now - perhaps mRNA vac for the lentivirus (HIV), plasmodium parasite (malaria) and TB bacteria will arrive too!
• Deaths: Covid-19 had killed 13.5 lakh by November 2020, while 25 lakh are killed annually by HIV-AIDS, malaria and TB.
• Vaccine deployment: The mRNA vaccine need very low temperatures to retain efficacy. Since the developing world has no national cold chains, these are of little use. But the technique is indeed the future of vaccines. Louis Pasteur had said "knowledge belongs to humanity and is the torch that illuminates the world".

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