< Vaccines
What are the different types of COVID-19 vaccines?
Text updated on 2021-01-28
There are 4 types of injectable vaccines against COVID-19 The vaccines include: messenger RNA vaccines, recombinant viral vector vaccines, inactivated whole virus vaccines, and protein subunit vaccines. In Europe, only certain messenger RNA or recombinant viral vector vaccines are licensed or are undergoing licensing.
Whatever the vaccine, the principle is the same: it involves presenting an exogenous element (virus, parasite, bacterium, new molecule) to our immune system so that it learns to recognize it and make specific antibodies that will be ready to neutralize it when encountered later on. The vaccine will allow the development of "memory" immune cells, capable of immediately recognizing the pathogen if it subsequently infects the individual. There are two types of targeted immune reactions: the humoral reaction (via antibodies) and the cellular reaction (via white blood cells designed to destroy the infecting element or infected cells). Both are durable: a few months to a few years for the antibodies (and memory cells will be able to make new ones), a few years or a lifetime for the white blood cells.
There are four types of COVID-19 vaccines:
1) RNA vaccines
These vaccines contain an RNA molecule, i.e., genetic material that will allow human cells to transiently produce certain proteins of the virus, but not whole coronaviruses. In the case of COVID-19, the messenger RNA encoding the Spike protein from SARS-CoV-2 is used. Isolated, this Spike protein does not make you sick, but it is recognized by the immune system, which will develop immune defenses against it. The RNA in the vaccine is fragile. It is protected by an envelope that may be synthetic (lipid particles for the Moderna and Pfizer vaccines) or derived from natural substances (see: https: //theconversation.com/comment-fonctionnent-les-vaccins-a-arn-et-a-adn-125267). It should be noted that the RNA vaccine is degraded within a few days by human cells.
examples:
- mRNA-1273 vaccine developed by Moderna and the National Institutes of Health
- BNT162b1 and BNT162b2 vaccines from Pfizer and BioNtech
2) Recombinant viral vector vaccines
Another way to get some of the genetic material of the coronavirus into human cells to produce some of the proteins in SARS-CoV-2 is to use a viral vector. This is a modified, harmless virus designed to carry genetic information. The viral vector used is not the one that causes COVID-19 but an adenovirus, a virus that causes certain colds in humans or chimpanzees. Once injected into the body, the adenovirus will temporarily infect the cells and allow them to produce a particular coronavirus protein (always the Spike protein for vaccines under development). This protein does not cause illness but is recognised by the immune system, which will then develop immune defences against it.
examples:
- AstraZeneca and Oxford University vaccine: an experimental chimpanzee adenovirus (ChAdOx1/AZD1222) vectorized vaccine encoding the Spike protein of the SARS-CoV-2
- Russian vaccine Sputnik V / COVINA-19 (rAd5-S and rAd26-S)
- adenovirus-vectored vaccine from the Chinese company CanSino Biologics
- Janssen vaccine (Ad26.COV2.S)
(3) Whole, inactivated, or attenuated virus vaccines
These are inactivated or attenuated whole viruses that are presented to the immune system. An inactivated virus is like a "dead" virus: it cannot multiply in the body. This virus is inactivated with formalin (Pasteur's technique) or by heat treatment. As for the attenuated virus, it is obtained by genetic selection: only a virus strain is kept that has acquired mutations making it harmless. In this case, the virus is still alive and can still multiply but without causing symptoms. There is a statistical risk, impossible to eliminate completely, that a tiny proportion of viral particles retain their ability to infect the individual. The latter technique is not used in the context of COVID-19.
examples:
- CoronaVac inactivated vaccine developed by Sinovac Life Sciences (China)
- inactivated vaccine from Sinopharm/Wuhan Institute of Virology (China)
- Covaxin inactivated vaccine in development with the Indian Council of Medical Research
4) Protein subunit vaccines
Instead of presenting the entire virus to the immune system, one of the proteins of the virus is simply injected. Usually the Spike protein of the coronavirus is chosen. In the Novavax vaccine, it is presented on small "rolls" of fat in which the proteins are planted as they would be on the surface of the coronavirus.
examples:
- Novavax vaccine (NVX-CoV2373), developed by Novavax and manufactured by Emergent Biosolutions
In addition to injectable vaccines, several vaccines for intranasal (nasal) administration are being developed to stimulate the specific defences of the mucous membranes of the nose, pharynx, bronchi, and lungs. They could be used alone or in addition to injectable vaccines.
Sources
Update on vaccines published on September 23, 2020 in the journal Nature.
Krammer, F. (2020). SARS-CoV-2 vaccines in development. Nature, 586(7830), 516-527.Article presenting the key points concerning the main vaccines developed against COVID-19.
Korsia-Meffre, S.(2020). Vaccines against COVID-19 an update on the ongoing Phase III trials. Vidal. Article published on October 8, 2020.Detailed and pictorial information on the different vaccines against COVID-19. Site updated regularly.
Zimmer, C., Corum, J., Wee, S.-L. (2021) Coronavirus Vaccine Tracker. New York Times.Phase I trials of the Moderna vaccine.
Jackson, L. A., Anderson, E. J., Rouphael, N. G., Roberts, P. C., Makhene, M., Coler, R. N., ... & Beigel, J. H. (2020). An mRNA vaccine against SARS-CoV-2-preliminary report. New England Journal of Medicine.Phase I trials of Moderna vaccine for people over 55 years of age.
Anderson, E. J., Rouphael, N. G., Widge, A. T., Jackson, L. A., Roberts, P. C., Makhene, M., ... & Beigel, J. H. (2020). Safety and immunogenicity of SARS-CoV-2 mRNA-1273 vaccine in older adults. New England Journal of Medicine, 383(25), 2427-2438.Phase I/II trials of Pfizer's vaccine.
Mulligan, M. J., Lyke, K. E., Kitchin, N., Absalon, J., Gurtman, A., Lockhart, S., ... & Jansen, K. U. (2020). Phase I/II study of COVID-19 RNA vaccine BNT162b1 in adults. Nature, 586(7830), 589-593.Phase I trials of the Pfizer vaccine.
Walsh, E. E., Frenck Jr, R. W., Falsey, A. R., Kitchin, N., Absalon, J., Gurtman, A., ... & Gruber, W. C. (2020). Safety and immunogenicity of two RNA-based Covid-19 vaccine candidates. New England Journal of Medicine, 383(25), 2439-2450.Astrazeneca vaccine trials.
Ramasamy, M. N., Minassian, A. M., Ewer, K. J., Flaxman, A. L., Folegatti, P. M., Owens, D. R., ... & Demissie, T. (2020). Safety and immunogenicity of ChAdOx1 nCoV-19 vaccine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised, controlled, phase 2/3 trial. The Lancet, 396(10267), 1979-1993.Phase I/II trials of the Russian Sputnik vaccine.
Logunov, D.Y., Dolzhikova, I.V., Zubkova, O.V., Tukhvatullin, A.I., Shcheblyakov, D.V., Dzharullaeva, A.S., ... & Gintsburg, A. L. (2020). Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia. The Lancet, 396(10255), 887-897.Phase I trials of the Cansino vaccine.
Zhu, F. C., Li, Y. H., Guan, X. H., Hou, L. H., Wang, W. J., Li, J. X., ... & Chen, W. (2020). Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomised, first-in-human trial. The Lancet, 395(10240), 1845-1854.Phase II trials of the Cansino vaccine.
Zhu, F. C., Guan, X. H., Li, Y. H., Huang, J. Y., Jiang, T., Hou, L. H., ... & Chen, W. (2020). Immunogenicity and safety of a recombinant adenovirus type-5-vectored COVID-19 vaccine in healthy adults aged 18 years or older: a randomised, double-blind, placebo-controlled, phase 2 trial. The Lancet, 396(10249), 479-488.Phase I trials of the Janssen vaccine.
Sadoff, J., Le Gars, M., Shukarev, G., Heerwegh, D., Truyers, C., de Groot, A. M., ... & Schuitemaker, H. (2020). Safety and immunogenicity of the Ad26. COV2. S COVID-19 vaccine candidate: interim results of a phase 1/2a, double-blind, randomized, placebo-controlled trial. MedRxiv.Institut Pasteur's description of attenuated vaccines.
https://professionnels.vaccination-info-service.fr/Aspects-scientifiques/Compositions-des-vaccins/Vaccins-vivants-attenuesInstitut Pasteur's description of inactivated vaccines.
https://professionnels.vaccination-info-service.fr/Aspects-scientifiques/Compositions-des-vaccins/Vaccins-inactivesPhase I/II trial of the Coronavac vaccine.
Zhang, Y., Zeng, G., Pan, H., Li, C., Hu, Y., Chu, K., ... & Zhu, F. (2020). Safety, tolerability, and immunogenicity of an inactivated SARS-CoV-2 vaccine in healthy adults aged 18-59 years: a randomised, double-blind, placebo-controlled, phase 1/2 clinical trial. The Lancet Infectious Diseases.Phase I/II trials of Sinopharm's vaccine.
Xia, S., Duan, K., Zhang, Y., Zhao, D., Zhang, H., Xie, Z., ... & Yang, X. (2020). Effect of an inactivated vaccine against SARS-CoV-2 on safety and immunogenicity outcomes: interim analysis of 2 randomized clinical trials. Jama, 324(10), 951-960.Phase I/II trial program for the Covaxin vaccine.
https://clinicaltrials.gov/ct2/show/NCT04471519Phase I/II trials of the Novavax vaccine (NVX-CoV2373).
Keech, C., Albert, G., Cho, I., Robertson, A., Reed, P., Neal, S., ... & Glenn, G. M. (2020). Phase 1-2 trial of a SARS-CoV-2 recombinant spike protein nanoparticle vaccine. New England Journal of Medicine, 383(24), 2320-2332.