Since the later part of December 2020, we are hearing the news of pharmaceutical companies developing the Covid-19 vaccine. Pharmaceutical companies in scientifically advanced countries such as USA, UK, Russia, Germany and China started receiving approval of their product by the regulatory authorities. That was the historic moment when humanity conquered the deadly virus. At present time, lot of us have received different types of Covid-19 vaccines. This blog is about the various vaccines available in the market all over the world, the different technologies adopted to develop the vaccine and the uptake of the same by world wide communities.
The Covid vaccines available are Pfizer -BioNtech, Moderna ,Oxford AstraZeneca, Sputnik, BBIBP, SINOVAC, COVAXIN, and Convidicea. Recently Johnson &Johnson Covid-19 vaccine has been approved. This vaccine is effective against South African variety. It has been reported that Novavax Covid -19 vaccine is going to be approved by the regulatory authority Medicines and Healthcare Products Regulatory Agency (MHRA)of the UK. In the vaccine development technology, different platforms are used. They are, mRNA based, inactivated virus, protein subunits, DNA based, Replicating viral vector and live attenuated virus. Majority of the viral vaccine developments were based on viral vector and RNA based technology. One thing very conspicuous about the coronavirus vaccine development is that the methods used are just like the methods used for developing other virus vaccines in the past. Let me explain more about the mechanism of technology. Pfizer- BioNtech vaccines are messenger RNA based vaccines whereby the mRNA is introduced into the human cell. It directs the cell to produce the spike protein of the coronavirus. This stimulates an adaptive immune response in the body to identify and destroy the corresponding pathogen.
In Oxford Astrazeneca vaccine technology, non-replicating viral vector, adenovirus in chimpanzees are used. Normally adenoviruses are DNA viruses which cause respiratory infections. The spike protein of the coronavirus is introduced into the adenovirus. This means coronaviruses are not replicating but the antigens introduced into the human body through vaccination, produce systemic immune response. This technology is otherwise called recombinant technology, used decades ago to develop Hep B vaccine. The Russian vaccine Sputnik and Johnson & Johnson vaccines also use the same methodology.
In other methods inactivated virus technology has been used whereby the viruses are killed with formaldehyde. In this group Chinese vaccine called Coronavac, BBIBP and Indian vaccine Covaxin are included. This usually does not entail good antigenic immune response as the viruses are dead. Another methodology of making vaccine is called protein sub unit vaccines. In this method small particles of protein antigen of coronavirus are introduced into the human body which evoke an immune response. Now we hear in the media about Novavax whose technology is based on protein subunit vaccines technology.
Pfizer-BioNtech vaccine is rolled out in UK, USA, EU and Japan, but its use is hampered by the logistics of storing it at -70 degree Celsius. Moderna vaccine has been reported to have been sold to rich countries like the US, UK and some countries in the EU. Oxford AstraZeneca vaccine was bought by Brazil,United Kingdom and India. It is the biggest vaccine supplier in the world endeavouring to preserve lives and open up economies all over the world through its 'moonshot' policy. Coronavac or Sinovac of China is used in Brazil, Indonesia, Chile and Turkey. BBIBP, the other Chinese vaccine has been used in United Arab Emirates, Bahrain, Jordan, Argentina, Pakistan, Morocco, and Peru. Sputnik vaccine is used in Russia, Belarus, India, Venezuela and UAE.
Effectiveness of a vaccine is defined as its capacity to prevent an
epidemic or pandemic. It differs from vaccine to vaccine and does not
have a yardstick to measure it exactly. Moderna claims to be having
96% effectiveness, followed by Pfizer-BioNtech at 95%, Novavax at 89%,
BBIBP at 79% and AstraZenecca at 62-90 %. It has been reported that vaccinating a different
vaccine in the second dose confers more immunity than giving the same
again in a conventional way. As on 5th February 2021, 101 million people were vaccinated all
over the world. In the US 32 million people were vaccinated, but by the
percentage of population UAE and Israel are at the top of the league. In
the UK, Covid-19 vaccine has been given to 11 million people, or nearly
17% people have got it as on 5th February 2021 and as such new cases and mortality are sharply declining.
As mortality and morbidity are higher in
the over sixties, the Joint Commission of vaccination and Immunisation
(JCVI) recommended priority in rolling out the vaccine to senior citizens and vulnerable people in
the community. In certain Asian countries, the priority is for 30 to 50 year group, to safeguard the manpower and economy. There are a lot of
people who are against vaccination, and make revulsive propaganda in the social media. They must be aware that
they owe their existence on earth to the advent of various vaccinations, against virus and bacteria in the 20th century. World Health Organisation reported that the last known case of small pox, another killer viral epidemic was in 1977. This was attained by the sustained vaccination regime against small pox in third world countries. Although Covid-19 death was significantly high in Black Asian Minority Ethnic Community (BAME), they are the main group shying away from taking the vaccine. If the covid-19 vaccination uptake is low in that community, there are chances of sporadic spread, once the pandemic is contained in general public. A poll conducted by National Geographic
demonstrated a gender gap on taking covid vaccine with 69% of men
compared to 51% of women in favour of the vaccine. This has shown correlation with education,
ethnicity and social status.
Science has not yet elucidated several
issues pertaining to the Covid vaccination. Given all viruses mutate, do
all approved vaccinations have effect on mutated virus? Do the vaccine manufactures need to update the genetic structure of the vaccine periodically? How long does
the protective effect of the vaccine last? Should the Covid-19 vaccine be taken annually like flu vaccine? What percentage of the
community should be vaccinated to attain herd immunity? What will be the long term side effects for Covid-19 vaccines? To safeguard
international travel, the covid-19 vaccination should be rolled out to
every country in the world. This will help airline industry, tourism and
the economy of less developed countries. Rich countries like the US as
well as the vaccine manufacturers should do everything possible to attain
that objective.
Dr. C.J.George
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