What Is A Vaccine
Most of us will know how a vaccine is delivered the vast majority will have had jabs as babies, or in school to protect against things like meningitis or measles, mumps and rubella . You can also get inoculated – which is the the process of actually receiving a vaccine – against flu which can be by injection or a nasal spray depending upon your age.
But each time you get vaccinated, what is actually happening to you?
BBC Bitesize spoke to Dr Sean Elias, a post-doctoral scientist at the University of Oxfords Jenner Institute, who is part of the team currently researching and trialling a potential vaccine for Covid-19.
Dr Elias explained: A vaccine is something you use to stimulate the immune systems response, mimicking an infection. Its a way of encouraging your body to produce an immune response that can protect you against a disease, much in the way you might react if you were infected with that disease normally.
Vaccines typically show small amounts of a virus or bacteria to the immune system and the bodys defences recognise them as an invader and learn to fight them. If you then catch that virus or bacteria for real, your body already knows what to do.
Our Covid-19 vaccine was developed in January. As scientists working on infectious diseases, we understood a pandemic like this could happen at any time and so in preparation our institute has a team that works specifically on outbreak diseases.
Making Vaccines For Good Public Health
Our manufacturing is state of the art, fueled by big data and digital technologies. Producing vaccines is where our passions come to life. Its the bridge between scientific breakthrough to transformative medicine for millions of people around the world.
We are adding two new Evolutive Vaccine Facilities to our worldwide industrial footprint. These EVFs represent the future of vaccine manufacturing, increasing our capacities while also making our production more flexible and more environmentally-friendly. Were in the building stage for one EVF site in France and one in Singapore.
What Risks Do Vaccines Pose
Like most medical treatments, any vaccine is accompanied by some degree of risk. Side effects are usually mild, ranging from soreness at the site of injection to a slight fever and body aches. In one in 100,000 cases, vaccines can trigger severe allergic reactions. Even more rare is an increased risk of developing autoimmune conditions that affect the nervous system, such as Guillain-Barre Syndrome.
Two separate studies involving live non-replicative vector virus vaccinesU.K.-based phase 3 AstraZeneca vaccine trial and U.S.-based phase 3 were briefly paused after a participant experienced an unexplained medical event known as an adverse reaction that may have been linked to their participation in the study. Both have since resumed after researchers and regulators determined that there was no clear connection between the vaccine and the medical events and deemed them safe enough to continue. No adverse events have yet been linked to the mRNA vaccine candidates, except for a handful of allergic reactions requiring EpiPens.
To hedge against uncertainty, the FDA added additional rules to provide increased safety by having specified checkpoints for the accelerated COVID-19 trials. That includes requiring researchers to collect at least two months of follow-up data from a majority of each trials participants, even if early data shows promising results, and long-term safety and efficacy out to two years after receipt of the vaccines.
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How Has A Covid Vaccine Been Developed So Quickly
Analysis: Funding and high public interest contributed to slashing of research and approval time
The emergence of vaccines against Covid-19 has been hailed as gamechanger by experts, but polls have revealed the speed of their development and approval is a matter of concern for some people. We take a look at how and why such processes were so rapid.
Treatment And Manifestation Of Hepatitis A And B
Hepatitis A has an incubation time of two to six weeks. Hepatitis B only manifests after two to six months. Often patients with hepatitis A and B infection have moderate to no signs of the infection.
In persons who show symptoms, they will get flu-like symptoms, which will occur about three to ten days before symptoms of the liver develop.
Thereafter, the urine will darken, and jaundice may grow. With jaundice, the skin and the whites of a person’s eyes have a yellow hue. The inflamed liver cannot conduct its normal biochemical processes, so a material called bilirubin increases in the body.
Typically, you tend to feel healthy when you have jaundice, even though you keep looking worse.
In hepatitis A the jaundice stage only lasts for about one week. After that, you’ll continue to heal and usually feel like your usual self within a month. You are immune for life after recovering from hepatitis A.
In hepatitis B, the jaundice stage is about two weeks.
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Birth Of A Vaccine: Chesterfield Missouri
Pfizer-BioNTech’s American vaccine is born in Chesterfield, not far from St. Louis, where the raw ingredients begin the process of becoming a vaccine.
It starts with circular snippets of DNA called plasmids. These carry the genetic material that codes for the notorious spike protein on the surface of SARS-CoV-2, the virus that causes COVID-19. The virus uses the spike to hook onto cells so it can infiltrate them and reproduce.
The DNA is made in large vats, said Christine Smith, vice president of Pfizer’s division of BioTherapeutics Pharmaceutical Sciences Medicinal Sciences. These hold hundreds of gallons of an amber-colored solution containing specially designed E. coli bacteria.
Using a process called biosynthesis, these bacteria churn out trillions of the DNA plasmids over the course of two weeks.
When completed, the solution goes through a purification process akin to straining spaghetti through a colander that removes everything but the microscopic loops of DNA.
Next, the loops are straightened out, or “linearized,” using enzymes to cut the circles. The lines of DNA in the now-clear solution are then packed into special high-tech bags about the size of a grocery bag and frozen to minus 112 F for storage.
Pfizer must vet the bag producer and check every lot that comes in, so it can verify they meet federal manufacturing guidelines. The bags cant fail, because each contains the building blocks of the COVID-19 vaccine.
Vaccine Development Testing And Regulation
Paul Offit, MD, describes the general process of making a vaccine.The College of Physicians of Philadelphia
Vaccine development is a long, complex process, often lasting 10-15 years and involving a combination of public and private involvement.
The current system for developing, testing, and regulating vaccines developed during the 20th century as the groups involved standardized their procedures and regulations.
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Vaccine Product Approval Process
The U.S. Food and Drug Administrations Center for Biologics Evaluation and Researchexternal icon is responsible for regulating vaccines in the United States.
The sponsor of a new vaccine product follows a multi-step approval process, which typically includes
- An Investigational New Drug application
- Pre-licensure vaccine clinical trials
- Presentation of findings to FDAs Vaccines and Related Biological Products Advisory Committeeexternal icon
- Usability testing of product labeling
After approving a vaccine, FDA continues to oversee its production to ensure continuing safety. Monitoring of the vaccine and of production activities, including periodic facility inspections, must continue as long as the manufacturer holds a license for the vaccine product.
FDA can require a manufacturer submit the results of their own tests for potency, safety, and purity for each vaccine lot. FDA can require each manufacturer submit samples of each vaccine lot for testing.
To learn about FDAs role in the vaccine approval process, consult FDAs Vaccine Product Approval Processexternal icon web page.
Pushing Manufacturing To The Next Level
Fully digitalized, our Evolutive Vaccines Facilities will enable more responsive and flexible manufacturing across multiple vaccine and biological platforms including mRNA, while minimizing our impact on the environment. Our EVFs will help improve peoples lives by giving them faster access to more vaccines and treatments.
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Assume We Already Understand The Coronavirus
Normally, researchers need years to secure funding, get approvals and study results piece by piece. But these are not normal times.
There are already at least 254 therapies and 95 vaccines related to Covid-19 being explored.
If you want to make that 18-month time frame, one way to do that is put as many horses in the race as you can, said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine.
Despite the unprecedented push for a vaccine, researchers caution that less than 10 percent of drugs that enter clinical trials are ever approved by the Food and Drug Administration.
The rest fail in one way or another: They are not effective, dont perform better than existing drugs or have too many side effects.
Fortunately, we already have a head start on the first phase of vaccine development: research. The outbreaks of SARS and MERS, which are also caused by coronaviruses, spurred lots of research. SARS and SARS-CoV-2, the virus that causes Covid-19, are roughly 80 percent identical, and both use so-called spike proteins to grab onto a specific receptor found on cells in human lungs. This helps explain how scientists developed a test for Covid-19 so quickly.
And yet, he said, this kind of fast-tracking is worth the try maybe we will get lucky.
First Steps: Laboratory And Animal Studies
This stage involves basic laboratory research and often lasts 2-4 years. Federally funded academic and governmental scientists identify natural or synthetic antigens that might help prevent or treat a disease. These antigens could include virus-like particles, weakened viruses or bacteria, weakened bacterial toxins, or other substances derived from pathogens.
Pre-clinical studies use tissue-culture or cell-culture systems and animal testing to assess the safety of the candidate vaccine and its immunogenicity, or ability to provoke an immune response. Animal subjects may include mice and monkeys. These studies give researchers an idea of the cellular responses they might expect in humans. They may also suggest a safe starting dose for the next phase of research as well as a safe method of administering the vaccine.
Researchers may adapt the candidate vaccine during the pre-clinical state to try to make it more effective. They may also do challenge studies with the animals, meaning that they vaccinate the animals and then try to infect them with the target pathogen.
Many candidate vaccines never progress beyond this stage because they fail to produce the desired immune response. The pre-clinical stages often lasts 1-2 years and usually involves researchers in private industry.
Once the IND application has been approved, the vaccine is subject to three phases of testing.
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Expediting Future Vaccine Development
The COVID pandemic has demonstrated that it is possible to develop, test and review multiple safe and effective vaccines against a new disease in less than a year. To have ended up with such encouraging efficacy results from more than one vaccine candidate puts us in an extraordinarily promising position, both in terms of ending the pandemic and developing vaccines against other diseases including future pathogens which could be the source of the next pandemic. But only if we remember the lessons learned during this extraordinary period.
How Will Eua Work
EUA stands for emergency use authorization.
Under EUA, the FDA is requiring that a COVID-19 vaccine be at least 50% effective at preventing symptomatic illness.
It is also requiring a median of two months of follow-up after completion of the vaccination for half of the vaccine recipients . This two-month period is to allow detection of an adverse event from the vaccine.
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Vaccine Review Approval And Monitoring
Health Canada’s independent drug review process is recognized around the world for its high standards and rigor. Our decisions are based only on scientific and medical evidence showing that vaccines are safe and effective. The benefits must also outweigh any risks.
The Pfizer-BioNTech COVID-19 vaccine was authorized for use in Canada under the Interim Order respecting the importation, sale and advertising of drugs for use in relation to COVID-19. The interim order expired on September 16, 2021. On this date, Pfizer-BioNTech Comirnaty®transitioned to an authorization under the Food and Drug Regulations.
Find detailed technical information such as the product monograph and the regulatory decision summary:
As COVID-19 vaccines are administered across Canada, our safety monitoring is ongoing. The Public Health Agency of Canada, Health Canada, and provincial and territorial health authorities continue to:
- monitor the use of all COVID-19 vaccines closely
- examine and assess any new safety concerns
The Pros Of Mrna Vaccines
In theory, the underlying technology behind mRNA vaccines is adaptable, allowing for quick updates as new viral mutations evolve or whole new viruses are discovered. Since mRNA vaccines are based on sequences of viral proteins, making a new vaccine could simply involve changing the mRNA sequence if you know what protein you want to make.
mRNA vaccines are also quicker and more reliably manufactured than traditional vaccines. For Moderna, the entire processfrom vaccine design to manufacturing to shipmenttook only 7 weeks. Although design and production of mRNA vaccines may take only weeks, necessary clinical trials to evaluate safety and efficacy still require several months of testing.
In contrast, other forms of vaccines use disabled or weakened viruses . These can take months or years to design. Manufacturing enough viruses to vaccinate a large portion of society can be a cumbersome process. For example, the influenza virus is grown inside fertilized chicken eggs, which are obtained from sterile laying facilities.
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Twinrix: The Vaccine For Hepatitis A And B
Both hepatitis A and B are identified by obtaining a blood sample, which you submit to a laboratory test. This test decides whether you have antibodies in the blood unique to those viruses. If the result is positive, you have been subjected to either hepatitis A or B.
To check whether anyone has hepatitis B, the test will see whether the individual has certain hepatitis B antigen levels.
Who Should Receive Twinrix
According to Canadian medical advice, the vaccine is required for all those seeking to minimize their hepatitis A and B infection risk. Twinrix is used for vaccinating adults, teenagers, youngsters and babies above one year of age.
In specific, vaccination against hepatitis A is suggested for:
- Travellers to countries or areas with a risk for hepatitis A
- The Canadian armed forces, emergency organization, or any other organization likely to be sent at short notice to high-risk areas for hepatitis A
- Zoo workers, veterinarians, and researchers
- People diagnosed with liver disease
Hepatitis B vaccination is prescribed for those who:
- Travellers to countries or areas with a risk for hepatitis B
- Nurses, including medical students
- People in contact with someone with hepatitis B
- People who use medication through injections
- Immigrants and students coming to Canada
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What Takes So Long
Despite differences in mRNA vaccines like Pfizer and viral vector vaccines like AstraZeneca, both take similar amounts of time to generate antibody responses. After a single dose of AstraZeneca, antibodies can be detected after 14 days and further increase over the next two weeks.
But why does it take time for these responses to develop? When researchers track the antibody response to the first dose of vaccine, they find it takes at least ten days for the immune system to start making antibodies that can recognise SARS-CoV-2s spike protein .
It also takes at least a week for T cells, a type of white blood cell important in our immune response, to start to react to the vaccine. Over the next few weeks, these responses become even stronger.
In contrast, the second dose activates the immune system much more quickly. Within a week of dose two, your antibody levels increase by more than ten times, providing much stronger and longer-lasting protection from infection.
So the first dose of a COVID vaccine gets your immune response going, but the second dose is essential to ensure immunity is strong, consistent from person to person, and longer-lasting.
Years And Years At Minimum
The vaccine development process has typically taken a decade or longer.
The next step in the process is pre-clinical and preparation work, where a pilot factory is readied to produce enough vaccine for trials. Researchers relying on groundwork from the SARS and MERS outbreaks could theoretically move through planning steps swiftly.
Sanofi, a French biopharmaceutical company, expects to begin clinical trials late this year for a Covid-19 vaccine that it repurposed from work on a SARS vaccine. If successful, the vaccine could be ready by late 2021.
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It Takes A Couple Of Weeks
Clinical trials show COVID vaccine protection is optimal from about two weeks after your second dose. This means they:
- nearly completely protect against severe disease and death in healthy people
- dramatically reduce the likelihood of symptoms with COVID-19
- reduce the likelihood of infection with the virus
- if you do get infected, they reduce the amount of virus you make. Emerging evidence suggests this reduces the likelihood you will pass the virus to other people.
Each dose of a vaccine essentially shifts the odds in your favour. One dose gives you a lower chance of reaping some of these benefits, while two doses gives you a much higher likelihood of these benefits.
Though even with two doses, you could still be unlucky and get infected, develop disease or pass on the virus.
Phase Iii Clinical Trials To Assess Safety And Efficacy
Phase III clinical trials are critical to understanding whether vaccines are safe and effective. Phase III trials often include tens of thousands of volunteers. Participants are chosen at random to receive the vaccine or a placebo. In Phase III, participants and most of the study investigators do not know who has received the vaccine and who received the placebo. Participants are then followed to see how many in each group get the disease. Assessing short- and long-term safety is also a major goal of phase 3 trials.
Phase 3 trials may take six to nine months to allow early assessment of safety and efficacy, particularly if conducted in areas with a high risk of infection, but with follow-up continuing for two years or more to assess long-term safety and efficacy.
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