effective COVID-19 vaccine?

 Which is the most effective COVID-19 vaccine?

The most effective COVID-19 Vaccine at this stage is as clear as mud !!

Having said that, I could throw some light on a few major vaccine categories and their frontrunners.

Viral Vector Vaccines: Viral vector vaccines use a modified version (rather weakened version) of a different virus as a vector to deliver instructions, in the form of genetic material (a gene), to a cell to emulate the viral spike protein. The vaccine does not cause infection with either COVID-19 or the virus that is used as the vector.

“I’m giving you the genes, create the virus and destroy it”.

The common viral vector vaccines available as of now are:

ChAdOx1/Covishield: Viral Vector vaccine developed by Oxford University partnering with AstraZeneca. A virus causing common cold in Chimpanzees known as the adenovirus, is weakened as to not replicate and act as a carrier or vector. In simpler words, you extract the genetic code of the spike of the Corona Virus and infuse it with the Adenovirus and then inject into human body. Upon injection, it creates an immuno response to the host and antibodies are generated. The major pro highlighted is that the vaccine induces immunity against adenovirus as well as Corona virus. Skepticism however exists as the viruses these days undergo significant mutation and if the immuno response induced merely to the spike protein would help in tackling future variants. A recent study has claimed that the Oxford-Astrazeneca COVID vaccine has proven to be 81.3% efficacious if the required two doses are given at an interval of 12 weeks. A few European nations had suspended the administration of the vaccine over reports of blood clots in some of those vaccinated.

Sputnik V: The Sputnik V vaccine vaccine is developed by the Gamaleya Research Institute of Epidemiology and Microbiology , the same government labs that created what is claimed as "effective against the Ebola virus, as well as a vaccine against the MERS virus.” It is a double vector vaccine based on adenovirus DNA, in which the SARS-CoV-2 coronavirus gene is integrated. The Sputnik jab uses two slightly different versions of the vaccine for the first and second dose - given 21 days apart. They both target the coronavirus's distinctive "spike", but use different vectors, ie two types of Adenovirus vectors rAd26 and rAd5. Russia's Sputnik V coronavirus vaccine gives around 92% efficacy against Covid-19, late stage trials published in lancet reveal. It has also been deemed to be safe - and offer complete protection against hospitalisation and death. clinical trials showed that the Sputnik V vaccine proved to be over 90% effective in individuals aged over 60 years.

Johnson & Johnson: Jannsen Vaccine developed by Johnson & Johnson is another viral vector vaccine which outweighs other vaccines in the fact that it is a single dose vaccine. The vaccine uses Adenovirus as the carrier similar to other viral vector vaccines, however, the vaccine was 66% effective in preventing symptomatic COVID-19 disease beginning 2 weeks after vaccination. Though the overall efficacy was reported to be 66%, it varied across the regions: 72 % in the U.S., 64 % in South Africa, and 61 % in Brazil. Experts suggest that the immunity doesn’t develop overnight and could take 2–4 weeks and that time would prove its worth.

Inactivated Virus Vaccines: Inactivated virus vaccines are usually made by exposure of virulent virus to chemical or physical agents in order to destroy infectivity while retaining immunogenicity. This simply means, you are injected with the dead virus incapable of replication yet is capable of inducing immuno response and producing antibodies. The underlying methodology, though conventional, is a well established and time tested one.

“I’m giving you a virus in coma, destroy it and prove your worth”

Some of the inactivated vaccines in the market now are,

Covaxin: An indigenous remedy rolled out by the Bharat Biotech in collaboration with ICMR(Indian Council of Medical Research) and NIV(National Institute of Virology). Medical professionals hope that since the whole virus is injected, the antibodies generated could tackle the mutant variants better. The recent reports of phase 3 trials demonstrated 81% interim efficacy in preventing COVID-19 in those without prior infection after the second dose.

CoronaVac: The Beijing-based biopharmaceutical company Sinovac is behind the CoronaVac, an inactivated vaccine. It works by using killed viral particles to expose the body's immune system to the virus without risking a serious disease response. Based on a Turkish study, Coronavac has an efficacy of 83.5% based on final results of Phase III trials.

Sinopharm Vaccines: developed by Sinopharm's Beijing Institute of Biological Products and the Wuhan Institute of Biological Products. Both vaccines are chemically-inactivated whole virus vaccines for COVID-19. In late December, Sinopharm announced that the vaccine, called BBIBP-CorV developed by Beijing Institute of Biological products , is more than 79% effective, according to preliminary data from late-stage clinical trials. The vaccine made by Chinese firm Sinopharm’s Wuhan subsidiary has a 72.5 per cent efficacy rate as per the reports in February.

mRNA Vaccines: Unlike a traditional vaccine that uses inactivated, dead, or portions of actual virus to spur an immune response, mRNA vaccine delivers a message to your body’s cells v that instructs the cells to generate the spike protein found on the surface of a coronavirus that initiates infection.

“I’m sending you the recipe, create the virus yourself and also destroy it yourself”

Some of the key mRNA vaccine players are :

Pfizer BioNTech: The Pfizer BioNTech’s COVID-19 vaccine is a messenger RNA (mRNA) vaccine that has both synthetic, or chemically produced, components and enzymatically produced components from naturally occurring substances such as proteins. The vaccine does not contain any live virus. Its ingredients help our cells replicate the viral spike and generate antibodies against it. Pfizer-BioNtech's Covid-19 vaccine offers at least 97 % effectiveness in symptomatic Covid-19 cases, according to real world data published by the pharma company. The analysis, based on real world data gathered by the Israel Ministry of Health, also found the vaccine's effectiveness at 94 % against asymptomatic SARS-CoV-2 infections. The vaccine appeared to be more or less equally protective across age groups and racial and ethnic groups. The vaccine ideally needs to be kept extremely cold: minus 70 degrees Celsius, which is colder than winter in Antartica. According to Pfizer/BioNTech, the new data demonstrates that their vaccine can be stored at temperatures of -25°C to -15°C, temperatures commonly found in pharmaceutical freezer and refrigerators.

Moderna (mRNA-1273) Vaccine: Developed by the United States National Institute of Allergy and Infectious Diseases (NIAID), the Biomedical Advanced Research and Development Authority (BARDA), and Moderna is another mRNA vaccine. The Moderna vaccine was 94.1% effective at preventing symptomatic Covid-19 after the second dose. The vaccine’s efficacy appeared to be slightly lower in people 65 and older, but during a presentation to the Food and Drug Administration’s advisory committee in December, the company explained that the numbers could have been influenced by the fact there were few cases in that age group in the trial. Moderna has said that its vaccine needs to be frozen too, but only at minus 20 Celsius, more like a regular freezer.

Which vaccine to pick up is totally upto the individual. Many vaccines are still under trial and hopefully foolproof single dose vaccines would come soon.