All you need to know: UAE's five Covid vaccines explained

Reuters

Dubai - Here’s a lowdown on the science behind each vaccine and other details.

Published: Mon 5 Jul 2021, 8:59 PM

Updated: Tue 6 Jul 2021, 9:57 AM

By
Suneeti Ahuja Kohli

The Ministry of Health and Prevention has approved the emergency use of Moderna’s Covid-19 vaccine in the UAE, making it the fifth vaccine to be allowed for use in the fight against the pandemic. The decision was made following the completion of clinical trials and an assessment, as well as the approval of the US Food and Drug Administration.

Here’s a lowdown on the science behind each vaccine and other details:

Moderna

>Date of approval in the UAE: July 4, 2021

>Efficacy rate: About 94 per cent at preventing symptomatic infection

>Number of doses needed: Two

>Time gap between the doses: 4 weeks

>Type of vaccine: mRNA

>Common side effects: Chills, headache, pain, tiredness, and/or redness and swelling at the injection site, all of which generally resolve within a day or two.

>Storage: It can be stored at regular freezer temperature and can be used within 30 days of thawing.

Pfizer-BioNTech

>Date of approval in the UAE: December 22, 2020

>Efficacy rate: Up to 95 per cent effective at preventing symptomatic disease

>Number of doses needed: Two

>Time gap between doses: 3 weeks between doses

>Common side effects: Chills, headache, pain, tiredness, and/or redness and swelling at the injection site, all of which generally resolve within a day or two of rest, hydration, and medications.

>Type of vaccine: mRNA

Storage: Pfizer vaccine requires a super-cold freezer and is only good for five days after thawing.

>How do mRNA vaccines work?

Messenger RNA (mRNA) is a relatively new technology which has been used to manufacture vaccine for Covid-19. As per Yale Medicine, unlike vaccines that put a weakened or inactivated disease germ into the body, the Pfizer-BioNTech and Moderna mRNA vaccines deliver a tiny piece of genetic code from the Sars-CoV-2 virus to host cells in the body, essentially giving those cells instructions for making copies of spike proteins. The spikes penetrate and infect host cells. These proteins then stimulate an immune response, producing antibodies and developing memory cells that will recognise and respond if the body is infected with the actual virus.

How well does it work on virus mutations?

Two studies done in early May this year on real-world use of Pfizer-BioNTech vaccine suggests strong protection against severe disease or death from the Alpha variant (first detected in the UK) and the Beta variant (first identified in South Africa). In case of the Delta variant (first seen in India), two studies reported by Public Health England showed that full vaccination (after two doses) is 88 per cent effective against symptomatic disease and 96 per cent effective against hospitalisation.

Oxford-AstraZeneca

>Date of approval in the UAE: January 2021

>Efficacy rate: 85 per cent

>Number of doses needed: Two

>Time gap between the doses: Four to 12 weeks apart

>Common side effects: Tenderness, pain, warmth, redness, itching, swelling or bruising at the injection site, all of which generally resolve within a day or two.

>Storage: It can be stored, transported, and handled in normal refrigeration for at least six months.

>How does it work?

The AstraZeneca vaccine is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees. It has been modified to contain genetic material shared by the coronavirus, although it can’t cause the illness. Once injected, it teaches the body’s immune system how to fight the real virus.

>How well does it work on variants?

According to a medical paper released in early February, two doses of the AstraZeneca vaccine has 74.6 per cent efficacy against the Alpha variant. However, the vaccine does not protect as much against mild and moderate cases in people infected with the Beta variant, which prompted South Africa to stop the use of the vaccine and opt for Johnson & Johnson and Pfizer-BioNTech. In case of the Delta variant, two recent studies show that full vaccination after two doses is 60 per cent effective against symptomatic disease and 93 per cent effective against hospitalisation.

Sputnik V

>Date of approval in the UAE: January 21, 2021

>Efficacy rate: 91.4 per cent

>Number of doses needed: Two

>Time gap between the doses: 21 days up to three months

>Storage: The vaccine can be stored at a temperature of 2 to 8 degrees Celsius.

>How does it work?

Sputnik V is based on adenoviral vector-based platform. Adenoviruses are a type of virus associated with the common cold and other illnesses. They serve as the delivery vehicle for the DNA instructions to produce the spike protein of the Sars-CoV-2 virus in the body. This then triggers the production of antibodies against this spike protein, preparing the immune system for a potential infection.

Each of the two doses uses a different type of adenovirus: first dose with type-26 (Ad26), then a booster dose with type-5 (Ad5). The purpose of using two different types is to lower the possibility of the body developing antibodies against the adenovirus after the first dose, which could make the second dose ineffective. Among the major Covid vaccines in development to date, only Sputnik V uses this approach. Others, such as the Oxford–AstraZeneca vaccine, use the same material for both doses.

>How well does it work on virus mutations?

According to a recent paper, Understanding the Covid-19 Variants of Concern, Sputnik V effectively protects against viruses with spike from the Alpha variant, but it is less effective against the Beta variant. Even though the developers of the vaccine claim it is around 90 per cent effective against the Delta variant, medical journals are yet to publish their results on this.

Sinopharm

>Date of approval in the UAE: December 9, 2020

>Efficacy rate: 86 per cent efficiency against Covid-19 infection

>Number of doses needed: Two

>Time gap between the doses: 21 to 28 days apart

>Common side effects: Much like other vaccines, the side effects of Sinopharm include flu-like illness, headache, fatigue, and injection-site reaction.

>Storage: This vaccine can be stored in the original packaging in a refrigerator at +2 to +8 °C.

>How does it work?

The Sinopharm vaccine contains inactivated Sars-CoV-2 virus that has undergone treatment with a chemical called beta-propiolactone. This chemical binds to the virus’ genetic material and stops it from replicating and causing Covid-19.

When an individual receives the vaccine, their body’s immune system identifies the inactivated virus as foreign and makes antibodies against it. If the vaccinated person subsequently comes into contact with Sars-CoV-2, their immune system launches an immune response against it.

>How well does it work on variants?

The World Health Organisation on its website states that this vaccine has not yet been evaluated in the context of circulation of widespread variants of concern. As per the Understanding of the Covid-19 Variants of Concern paper, Sinopharm did trigger an immune response against the Beta variant. However, there is not much data available on its efficacy on the other two variants: Alpha and Delta.

‘THE BEST VACCINE’

Even though each Covid-19 vaccine is unique, the best vaccine is the one that’s in your arm. If you haven’t taken the vaccine yet, medical experts recommend getting one to achieve herd immunity. All the vaccines authorised for use in the UAE are effective at preventing you from severe infection from Sars-Cov-2.

suneeti@khaleejtimes.com