Seven coronavirus vaccines are rolling out across six continents to slow the global pandemic, and more are in late-stage testing. The shots use different technologies to help people mount the molecular defenses that can fend off Covid-19.
Vaccines from Moderna Inc. MRNA 3.86% and Pfizer Inc. PFE -2.61% and its German partner BioNTech BNTX 1.01% SE mobilize immune defenses using genetic molecules known as messenger RNA packaged in fat envelopes, while AstraZeneca Inc.’s AZN -2.65% vaccine and Russia’s Sputnik V shot deliver immune prompts with the help of common, harmless viruses. A Beijing-based drug-development unit of China National Pharmaceutical Group Co., known more commonly as Sinopharm, relies on the traditional vaccine approach: prompting immune defenses against a dangerous virus by injecting a defanged version of the pathogen. Another vaccine, now in late-stage testing from U.S.-based Novavax Inc., NVAX 0.86% relies on a fourth technology.
The vaccines appeared to have different levels of effectiveness during testing, and different side effect risks. The following explains how each of these vaccines works.
Genetic-Code
The mRNA technology behind the Pfizer and Moderna vaccines—the two currently in use in the U.S.—had never been approved before the pandemic. Messenger RNA carries to cells the genetic instructions for making proteins. The mRNA vaccines ferry orders, engineered in a lab, for making a harmless version of the protein from the novel coronavirus, prompting cells to make the protein and the immune system to mobilize molecular defenses that can spring into action if exposed to the real coronavirus.
Among the Covid-19 vaccines currently in use, mRNA vaccines have had the highest efficacy rates during late-stage testing.
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists have identified the genetic code that coronavirus uses to produce
spike proteins. They employ molecules called RNA to ferry this genetic information into our cells. The RNA is protected by a lipid coating.
RNA
encased in lipid coating
Spike
proteins
When injected into a patient, the RNA enters healthy cells where it helps orchestrate the production of coronavirus spike proteins.
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditonal vaccines.
Vaccine-generated antibody response
Spike protein
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists have identified the genetic code that coronavirus uses to produce
spike proteins. They employ molecules called RNA to ferry this genetic information into our cells. The RNA is protected by a lipid coating.
Spike
proteins
RNA
encased in lipid coating
When injected into a patient, the RNA enters healthy cells where it helps orchestrate the production of coronavirus spike proteins.
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditonal vaccines.
Vaccine-generated antibody response
Spike protein
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists have identified the genetic code that coronavirus uses to produce
spike proteins. They employ molecules called RNA to ferry this genetic information into our cells. The RNA is protected by a lipid coating.
RNA
encased in lipid coating
Spike
proteins
When injected into a patient, the RNA enters healthy cells where it helps orchestrate the production of coronavirus spike proteins.
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditonal vaccines.
Vaccine-generated antibody response
Spike protein
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Spike proteins
Scientists have identified the genetic code that coronavirus uses to produce
spike proteins. They employ molecules called RNA to ferry this genetic information into our cells. The RNA is protected by a lipid coating.
RNA encased in lipid coating
When injected into a patient, the RNA enters healthy cells where it helps orchestrate the production of coronavirus spike proteins.
Spike protein
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditonal vaccines.
Vaccine-generated antibody response
Moderna
• Available in: U.S., Canada, parts of Europe, Israel
• Doses: 2
• Efficacy: 94%
• Most common side effects: Injection-site pain, fatigue, headache, muscle pain
Pfizer
• Available in: U.S., Canada, Mexico, U.K., parts of Europe and the Middle East, Ecuador and Singapore
• Doses: 2
• Efficacy: 95%
• Most common side effects: Injection-site pain, fatigue, headache, muscle pain
Virus-Based
Two of China’s vaccines rely on the traditional vaccine method, much like the technology behind shots for the flu or polio. These traditional vaccines use a killed or weakened form of the targeted virus to generate an immune response that can protect against the pathogen. So far, studies on the effectiveness of Covid-19 vaccines using the traditional technology have shown them to have lower efficacy rates than other shots with late-stage study results.
In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.
After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.
Weakened virus vaccine
Actual viral infection
antibodies
In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.
After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.
Weakened virus vaccine
Actual viral infection
antibodies
In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.
After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.
Weakened virus vaccine
Actual viral infection
antibodies
In classic vaccines, such as those against measles and polio, the patient is inoculated with weakened or inactivated versions of the virus. This triggers the immune system to produce specialized antibodies that are adapted to recognize the virus.
Weakened virus vaccine
antibodies
Actual viral infection
After vaccination, the antibodies remain in the body. If the patient later becomes infected with the actual virus, the antibodies can identify and help neutralize it.
China’s state-owned Sinopharm
• Available in: China, Bahrain, Serbia, U.A.E., Seychelles
• Doses: 2
• Efficacy: 79%, interim Phase 3 results
• Most common side effects: Injection-site pain, headache, muscle pain, fever
Sinovac Biotech Ltd.
• Available in: China, Brazil, Indonesia, Turkey
• Doses: 2
• Efficacy: 50% (based on clinical trials in Brazil)
• Most common side effects: Unknown
Viral Vectors
Several vaccines use what is known as a viral-vector approach, a reference to how the shots deliver immune-mobilization orders. The technology is behind some relatively new vaccines to protect against another deadly infectious disease, Ebola.
Among the viral-vector Covid-19 vaccines are AstraZeneca’s, developed with the University of Oxford and in use in the U.K. and across Europe; Russia’s Sputnik V; a vaccine from China’s CanSino Biologics Inc., 6185 -9.47% working with the Chinese military. The shots use a modified virus—like the virus responsible for common colds—to carry genetic instructions teaching cells to make a protein from the coronavirus.
A fourth viral-vector vaccine, from Johnson & Johnson, JNJ -0.23% is in late-stage testing and could be authorized for use in the U.S. as early as February.
Instead of using the whole virus to generate an immune response, the vaccine relies on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists have isolated genes in the new coronavirus responsible for producing these spike proteins. The genes are spliced into weakened, harmless versions of other viruses.
Weakened virus with
spike protein genes
Spike
proteins
When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditional vaccines.
Spike protein
Vaccine-generated antibody response
Instead of using the whole virus to generate an immune response, the vaccine relies on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists have isolated genes in the new coronavirus responsible for producing these spike proteins. The genes are spliced into weakened, harmless versions of other viruses.
Weakened virus with
spike protein genes
Spike
proteins
When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditional vaccines.
Spike protein
Vaccine-generated antibody response
Scientists have isolated genes in the new coronavirus responsible for producing these spike proteins. The genes are spliced into weakened, harmless versions of other viruses.
Instead of using the whole virus to generate an immune response, the vaccine relies on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Weakened virus with
spike protein genes
Spike
proteins
When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditional vaccines.
Spike protein
Vaccine-generated antibody response
Instead of using the whole virus to generate an immune response, the vaccine relies on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Spike proteins
Scientists have isolated genes in the new coronavirus responsible for producing these
spike proteins. The genes are spliced into weakened, harmless versions of other viruses.
Weakened virus with
spike protein genes
When injected into a patient, the genetically engineered viruses enter healthy cells where they produce coronavirus spike proteins.
Spike protein
Once exported from the cells, the spike proteins prompt the immune system to mount a defense, just as with traditional vaccines.
Vaccine-generated antibody response
AstraZeneca
• Available in: U.K.
• Doses: 2
• Efficacy: 62% (with two doses)
• Most common side effects: Unknown
Johnson & Johnson
• Not yet approved for distribution
• Doses: 1 or 2, pending outcome of clinical trials
• Efficacy: Unknown
• Most common side effects: Fatigue, headache, muscle pain, injection-site pain
Sputnik V
• Available in: Russia, Serbia, Argentina
• Doses: 2 (Russia is also offering to foreign customers who want to speed up vaccinations a one-dose version, Sputnik Light, consisting of the first dose of the regular Sputnik vaccine.)
• Efficacy: 91.4%, in an interim analysis
• Most common side effects: Injection-site pain and flu-like symptoms including fever, weakness, fatigue and headache
CanSino Biologics, working with the Chinese military
• Available in: China
• Doses: 1
• Efficacy: Unknown
• Most common side effects: Unknown
Protein-Based
Researchers designed these vaccines to generate an immune response to the coronavirus by introducing one of its proteins, like the spike protein jutting from its surface. The presence of the protein, or something resembling it, should provoke the immune system to develop defenses against the virus, the researchers say. Covid-19 vaccines based on the technology aren’t available yet. Novavax’s shot, which is in late-stage testing, could be rolled out in the U.S. in spring or summer if it proves to work safely.
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists make the protein by genetically modifying an unrelated insect virus, the baculovirus, and then using that modified virus to infect insect cells cloned from the armyworm moth.
Coronavirus spike protein
Baculovirus
Modified virus
This vaccine is made from a stabilized form of the coronavirus spike protein using recombinant protein nanoparticle technology
The purified protein antigens in the vaccine cannot replicate and cannot cause Covid-19. The vaccine also contains additives that enhance desired immune system responses to vaccine.
Stabilized spike protein
Vaccine-generated antibody response
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists make the protein by genetically modifying an unrelated insect virus, the baculovirus, and then using that modified virus to infect insect cells cloned from the armyworm moth.
Coronavirus spike protein
Baculovirus
Modified virus
This vaccine is made from a stabilized form of the coronavirus spike protein using recombinant protein nanoparticle technology
The purified protein antigens in the vaccine cannot replicate and cannot cause Covid-19. The vaccine also contains additives that enhance desired immune system responses to vaccine.
Stabilized spike protein
Vaccine-generated antibody response
Instead of using the whole virus to generate an immune response, these vaccines rely on coronavirus’s outer spike proteins, which are what antibodies use to recognize the virus.
Scientists make the protein by genetically modifying an unrelated insect virus, the baculovirus, and then using that modified virus to infect insect cells cloned from the armyworm moth.
Coronavirus spike protein
Baculovirus
Modified virus
This vaccine is made from a stabilized form of the coronavirus spike protein using recombinant protein nanoparticle technology
The purified protein antigens in the vaccine cannot replicate and cannot cause Covid-19. The vaccine also contains additives that enhance desired immune system responses to vaccine.
Stabilized spike protein
Vaccine-generated antibody response
Coronavirus spike protein
Scientists make the protein by genetically modifying an unrelated insect virus, the baculovirus, and then using that modified virus to infect insect cells cloned from the armyworm moth.
Baculovirus
Modified virus
This vaccine is made from a stabilized form of the coronavirus spike protein using recombinant protein nanoparticle technology
Stabilized spike protein
The purified protein antigens in the vaccine cannot replicate and cannot cause Covid-19.
The vaccine also contains additives that enhance desired immune system responses to vaccine.
Vaccine-generated antibody response
Novavax
• Not yet approved for distribution
• Doses: 2
• Efficacy: Unknown
• Most common side effects: Injection-site pain, fatigue, headache, muscle ache
Sources: Our World In Data (for distribution locations); World Health Organization (doses)
Write to Peter Loftus at [email protected]
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