How Do Vaccines Work and Are They Safe?
For more than two centuries, vaccines have been essential in the struggle to maintain public health. After British physician Edward Jenner developed the smallpox vaccine using the cowpox virus in 1796, medical professionals have used vaccines to prevent deadly plagues including cholera, polio and influenza.
The global response to the COVID-19 pandemic has focused on developing a vaccine that can provide at least some level of immunity to infection. In recent weeks, major pharmaceutical companies including Pfizer and AstraZeneca have announced successes in vaccine development, but many questions remain unanswered.
How Does a Vaccine Protect You?
Vaccines operate on a very simple principle: boost your immune system so that you can fight off infection. They do this by mimicking the pathogen which causes your immune system to produce antibodies. These antibodies attack any of the authentic pathogen if they enter the body and prevent it from multiplying and becoming a full-blown infection.
A vaccine produces this immune response in one of five ways:
- Live attenuated vaccine—these vaccines contain a live form of the pathogen that have been weakened. The live virus or bacteria is too weak to produce an infection but is sufficient to initiate an immune response. Children and others with weakened immune systems should not receive this kind of vaccine.
- Inactivated vaccine—this kind of vaccine has a dead or inactivated form of the virus or bacteria. Normally, multiple doses of inactivated vaccines are necessary to produce the intended immune response.
- Toxoid vaccines—these vaccines protect against bacteria that manufacture poisons. The toxins are weakened enough that they can’t harm the patient but spur the production of antibodies that can fight off the bacteria.
- Subunit vaccines—these vaccines contain only a portion of the germ. This subunit is sufficient to produce antibodies, but there is less risk of potentially dangerous side effects.
- Conjugate vaccines—the conjugate vaccine defend against bacteria with polysaccharide antigens. The vaccines make the antigens more prominent and recognizable so that an antibody can be produced.
You should understand that vaccines protect you by making your immune system more resistant to infection, but it also protects entire communities. If enough people are vaccinated, then a disease can die out due to a lack of hosts. This herd immunity principle is why smallpox has been completely eradicated; although not everyone has been immunized against smallpox, enough have that the smallpox germ couldn’t survive in the population.
The typical public health goal is to vaccinate 70 percent of a population. That is enough to starve a virus of potential hosts and kill it off. This goal is much more realistic since young children, seniors, pregnant women and people with compromised immune systems often can’t be immunized.
How Are Vaccines Made?
The process of creating a vaccine is a long and complicated one. Initially, there is a lot of research that identifies the pathogen—a virus or bacteria—and the specific antigen that the vaccine should mimic. Then the germ is weakened, killed or subdivided as needed for the type of vaccine.
Once a vaccine is produced, it undergoes a vigorous safety testing procedure that includes
- Pre-clinical testing—this testing is performed on animals to determine if it is safe and produces the desired immune response.
- Phase 1—a small group of human volunteers receive the vaccine. These volunteers are usually young, healthy adults. This phase helps gauge the safety and the proper dosage.
- Phase 2—a few hundred volunteers are vaccinated in this test phase. These volunteers come from a broader range of the population.
- Phase 3—tens of thousands of volunteers receive the vaccine with many of these living in areas where there are high rates of infection. The purpose of this phase which may take years is to evaluate its effectiveness against infection and identify any potentially dangerous adverse effects.
Upon successful completion of Phase 3, the manufacturer may apply for approval for distribution. Even after approval, regulatory bodies will monitor the population for adverse reactions.
In early November, Pfizer announced that its vaccine could keep 90 percent of those inoculated safe from COVID-19. Out of 40,000 volunteers in the trial, only 94 had gotten infected with COVID-19. The Pfizer vaccine required two shots 60 days apart. Pfizer states that improved immunity begins 28 days after the initial dose, and this efficacy covered all age groups.
The Pfizer vaccine is a mRNA form, one of the first of its kind. Instead of introducing a part of the coronavirus into the patient, the mRNA enters the human cells and begins to produce the desired antibody.
There were no major adverse effects found with the Pfizer vaccine. The most common side effects were fatigue and headache. Out of the 40,000 volunteers, only ten severe COVID-19 infections occurred. Nine of these occurred in the placebo group and one in the vaccinated group.
There was also good news coming out of the Oxford and AstraZeneca. Although their vaccine only has a 70 percent efficacy rate, it is much cheaper to produce and easier to transport. Because of the delicacy of some ingredients, the Pfizer vaccine must be kept at 100 degrees below zero. The Oxford/AstraZeneca vaccine can be kept at 36-46 degrees Fahrenheit for up to six months. The Oxford/AstraZeneca vaccine only costs about $3 to $4 per dose, while the Pfizer vaccine costs about $20 per dose.
The lower cost and ease of transport of the Oxford/AstraZeneca vaccine makes it more accessible to poorer nations. Unlike Pfizer which has to create a supply chain that maintains very cold temperatures, the Oxford vaccine can be distributed using existing refrigeration protocols.
In the long run, the Oxford/AstraZeneca vaccine may prove more effective at killing COVID-19 than the more efficacious vaccines. In order to bring this pandemic under control, around 70 percent of the global population must acquire immunity. That means that a more accessible vaccine may be the solution that the world needs to return to normalcy.
Article written by: Dr. Robert Moghim – CEO/Founder Colorado Pain Care
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