An overview of COVID-19 vaccine technology in China, India and Cuba – fr

An overview of COVID-19 vaccine technology in China, India and Cuba – fr

COVID-19 vaccines developed in China are already in use in several countries around the world. And some developed in India, Kazakhstan and Cuba were used nationally for their own populations even before the completion of phase 3 trials.
Vaccines made in some of these countries (including the Serum Institute of India’s Covishield version of the AstraZeneca vaccine) use viral vector technology or mRNA technologies used to inoculate Canadians. But other nationally developed vaccines are quite different.

Here is an overview of two types of COVID-19 vaccines – inactivated and conjugate protein vaccines – developed in middle-income countries and not available in Canada.

Inactivated vaccines

Who do this: Vaccines of this type have been developed by Sinovac (CoronaVac), headquartered in Shanghai, China and Sinopharm (BBIBP-CorV), in Beijing, China, Bharat Biotech (Covaxin) in Hydrabad, India and The Institute for Research on Biosafety Problems (QazVac) in Zhambyl, Kazakhstan.

How they work: This is a proven and true strategy used in many vaccines against diseases such as hepatitis A and rabies. It’s about growing whole viruses – in this case SARS-CoV-2, the virus that causes COVID-19 – and then inactivating them so they can’t cause infection. For SARS-Cov-2, inactivation is usually done with a chemical called beta-propiolactone. The virus is injected with an adjuvant, usually aluminum-based, to stimulate the immune response. Unlike mRNA vaccines, these vaccines also do not require ultra-cold storage. A regular refrigerator will do.

How inactivated COVID-19 vaccines are made and how they work. (CBC News)

What stage are they at? The first are China’s inactivated vaccines, already approved for emergency use and used for mass vaccination in dozens of countries around the world on almost every continent. They were evaluated by the World Health Organization for the list of emergency uses this spring. Bharat Biotch published the provisional results of phase 3 for its Covaxin vaccine in March and April, and the vaccine has been in use in its home country since January, when it was approved for emergency use in that country. Likewise, the Institute for Research on Biosafety Problems rolled out its QazVac vaccine on April 23, about halfway through the completion of its Phase 3 trials.

How good are they? None have published final results from their Phase 3 trials, but all results so far exceed the World Health Organization’s minimum 50% effectiveness:

People wait to receive Bharat Biotech’s COVAXIN vaccine against COVID-19 at an indoor stadium in Gauhati, India on Thursday, April 22, 2021. The inactivated vaccine has been in use in India since January. It released interim results from the Phase 3 trials in March and April. (Anupam Nath / The Associated Press)

Colin Funk, Adjunct Professor at Queen’s University in Kingston, Ont., And Biomedical Consultant at Novateur Ventures in Vancouver co-authored an article in the journal Viruses earlier this year comparing all the leading vaccines in the world, including those from Sinovac and Sinopharm.

“They work, but not as well as mRNA vaccines,” he said. Pfizer and Moderna both reported efficiency of over 94%. Funk said it is difficult to get reliable information because Chinese companies have not released their final results. However, since they are used in many countries, he added that it should become clear in a few months how well they are working.

Although officially the effectiveness of these vaccines is lower, they do have one advantage – fewer side effects, especially fever. It’s the side effect that may cause the most concern, said Craig LaFerriere, head of vaccine development at Novator Ventures, who co-authored the article with Funk. Fever occurs in less than 2% of people vaccinated with inactivated vaccines, compared to 15% of those who receive mRNA and viral vector vaccines.

Conjugate vaccines

Who do this: There are at least two Cuban vaccines of this type, billed as the only COVID-19 vaccines of their kind: Soberana 02 (the name means “sovereignty”), manufactured by the Finlay Institute for Vaccines in Havana; and Mambisa, developed by the Center for Genetic Engineering and Biotechnology (CIGB).

How they work: Conjugate protein vaccines are a special type of protein subunit vaccine made with an antigen (a substance that can cause an immune response) from the target disease linked with a strong antigen from another disease to stimulate the immune response. A common vaccine that you have probably been vaccinated with is Haemophilus influenza type b (Hib), a standard childhood meningitis vaccine, which includes sugar coating or Hib polysaccharide bound to a diphtheria, meningococcal, or tetanus protein. In the case of Soberana 02, the receptor binding domain of the spike protein of the SARS-CoV-2 virus responsible for COVID-19 is linked to a tetanus toxoid, Cuban Doctors Reported In Global Health Journal BMJ . A second Cuban conjugate vaccine, Mambisa, contains the same coronavirus protein and a hepatitis B protein. Protein vaccines can be stored in a regular refrigerator.

How conjugate vaccines for COVID-19 work and how they are made. (CBC News)

What stage are they at? Soberana 02 is one of two Cuban vaccines listed by the World Health Organization as currently in Phase 3 advanced clinical trials (the other is Abdala, a traditional protein subunit vaccine with adjuvant aluminum-based). It is already being used in Havana as part of an “interventional study”, which does not involve double-blind testing or placebos. Mambisa, designed to be given as a nasal spray instead of an injection, began Phase 1 trials in March.

How good are they? We do not know. Data from the trials have not been published or published, although there is preclinical results published on a pre-print server. Vicente Vérez Bencomo, Director General of the Finlay Institute told Nature newspaper in April that the phase 1 and 2 trials of Soberana 02 showed that 80% of people who received two doses had an antibody response. Some received an additional booster in the form of Soberana Plus, a version of the vaccine intended for those who have already had COVID-19 and 100% of them showed an antibody response, he added.

Health workers are testing volunteers for the Soberana-02 COVID-19 vaccine as part of phase 3 of one of two experimental Cuban vaccines in Havana on Wednesday March 24, 2021. (Ramon Espinosa / Photo de la piscine / The Associated Press)

But Cuba has managed to make a Hib vaccine based on this technology and has decades of experience with it, said Helen Yaffe, a lecturer in economic and social history at the University of Glasgow, who has studied the biotechnology industry. public of Cuba. “I think most countries around the world take Cuba’s biotech products very seriously,” she said. Funk from Queen’s University agreed that Cuba is doing very good research and said of Soberana 02: “I think it would be a candidate that could progress and that could be used in some countries around the world,” Funk said. . “We’ll just have to see. ”


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