Why should you take the COVID19 vaccine?
To understand how vaccines work, let’s review how the body’s immune system works to protect us against disease. Our immune system is a specialized network of organs, cells, and tissues that all work together to protect against infection. When a disease-causing microbe (for example, a virus or bacteria) enters the body, the immune system:
Recognizes the germ as being foreign (not belonging in the body).
Responds by making unique proteins (called antibodies) that help destroy the germ. Most of the time, the immune system can’t act fast enough to stop the microbe from making one sick. But by eliminating the microbe can usually help one get well again.
Remembers the germ that made one sick and how to destroy it. Upon future exposure to the same microbe, the immune system can quickly kill it before it has a chance to make one sick. This protection is called immunity.
Vaccines and immune system
Vaccines give immunity to a disease without one getting sick first. The main goal of a vaccine for a particular infectious agent, like a virus, is to teach the immune system what that agent looks like. Once educated, the immune system will vigorously attack the actual virus if it ever enters the body. Vaccines use killed or weakened versions of the disease-causing germ or parts of the microbe (called antigens). For some vaccines, genetic engineering helps make the antigens used in the vaccine. It’s much safer to get a vaccine than to get the disease it prevents.
What are viruses?
A virus is a small collection of genetic code, either DNA or RNA, surrounded by a protein coat. It is not alive and cannot replicate alone. Viruses must infect cells and use components of the host cell to make copies of themselves. Often, they kill the host cell in the process and cause damage to the host organism. The virus’s DNA or RNA genes make messenger RNA (mRNA); the mRNA then makes the proteins to make the protein coat. An mRNA of a specific structure makes a protein of a particular design.
Vaccines against viruses
Some traditional vaccines use a weakened virus, while others use just a critical piece of the virus’s protein coat. In the case of COVID-19, a part called the spike protein is the critical piece. Traditional vaccines are very effective. They have wiped off diseases like Polio and Smallpox from the face of this earth. Collectively, vaccines may have done more good for humanity than any other medical advance in history. But growing large amounts of a virus and then weakening the virus or extracting the critical piece takes a lot of time.
The invention of mRNA vaccines
Three decades ago, scientists began exploring more straightforward ways to make vaccines. After discovering genetic codes, it became relatively easy to make mRNA in the laboratory in large amounts. The researchers keep looking for the mRNA’s exact structure (such as spike protein of SARS-CoV-2 virus) that made the critical piece of a virus’s protein coat. They wondered if you injected that mRNA into someone, and the mRNA then traveled through the bloodstream to be gobbled up by immune system cells, and then those cells started to make the spike protein? Would that educate the immune system?
Although this concept seemed simple, it took decades of intense research. Scientists learned how to modify mRNA so that it did not produce violent immune system reactions. Then they learned how to encourage immune system cells to gobble up the mRNA as it passed in the blood. After that, they learned how to coax those cells to make large amounts of the critical piece of protein. Finally, they learned how to enclose the mRNA inside microscopically small capsules to protect it from being destroyed by chemicals in our blood. Along the way, they also learned that, compared to traditional vaccines, mRNA vaccines could generate a robust type of immunity: they stimulate the immune system to make antibodies and immune system killer cells — a double strike at the virus. Several companies have been working painstakingly to bring mRNA vaccine technology to the actual working threshold. The companies had built platforms that, theoretically, could be used to create a vaccine for any infectious disease by merely inserting the right mRNA sequence for that disease.
Then along came COVID-19. Within weeks of identifying the responsible virus, scientists in China had determined the structure of all of its genes, including the genes that make the spike protein and published this information online. Within minutes, scientists 10,000 miles away began working on the design of an mRNA vaccine. Within weeks, they had made enough vaccines to test them in animals and then in people. Just 11 months after discovering the SARS-CoV-2 virus, regulators in the US and the United Kingdom confirmed that an mRNA vaccine for COVID-19 is effective and safely tolerated, paving the path to widespread immunization. No new vaccine has ever taken less than four years to make.
All of these discoveries depended on scientists’ willingness to persist in pursuing their longshot dreams — often despite enormous skepticism and even ridicule — and the willingness of society to invest in their research. Future mRNA vaccine technology may allow for one vaccine to protect multiple diseases, thus decreasing the number of shots needed for protection against common vaccine-preventable diseases. Beyond vaccines, cancer research has used mRNA to trigger the immune system to target specific cancer cells.
Facts about COVID-19 mRNA Vaccines
They cannot give someone COVID-19.mRNA vaccines do not use the live virus that causes COVID-19.
They do not affect or interact with our DNA in any way. mRNA never enters the cell’s nucleus, where our DNA (genetic material) is kept. The cell breaks down and gets rid of the mRNA soon after it is finished using the instructions.
Corners were not cut in the clinical trials and approvals process. Vaccine trials take place in stages, starting with trials on animals. Three trials on people – Phase 1, Phase 2, and finally Phase 3.Regulatory agencies reviewed the data from Covid-19 vaccine trials more quickly than usual by looking at it on a rolling basis rather than only once the trials were complete. Still, they did not fundamentally change their rules. The process was faster than usual because researchers had already built an mRNA platform – a way of getting viral mRNA into the body – for cancer and other vaccines under trial. It meant this could be put into action as soon as the virus’s genomic sequence was shared. Companies and governments also took the risk of producing large numbers of vaccines even before the first stages of experimentation had been completed, which meant they were ready to begin large human trials as soon as the results were in.
The vaccine triggers an inflammatory response. The vaccine partly works by inducing local inflammatory reactions to activate the immune system. This means that it’s normal for many people to experience pain at the injection site and sometimes fever and discomfort for one or two days after the vaccine. One unwanted response to the Pfizer-BioNTech mRNA vaccine came to light during the first day of mass vaccination in the UK after two people with a history of significant allergies reacted to the injection. A history of a severe allergic reaction (e.g., anaphylaxis) to any other vaccine or injectable therapy (e.g., intramuscular, intravenous, or subcutaneous) is a precaution, not a contraindication to vaccination.
We received the Pfizer COVID-19 vaccine today and hope you also take it. The highest risk right now (especially for vulnerable people) is not to be vaccinated.
Clinical considerations for the use of Pfizer-BioNTech COVID-19 vaccine
Administration
2-dose series administered intramuscularly 3 weeks apart
Administration of 2nd dose within the 4-day grace period (e.g., day 17-21) considered valid
If >21 days since 1st dose, 2nd dose should be administered at the earliest opportunity (but no doses need to be repeated)
Both doses are necessary for protection; the efficacy of a single dose has not been systematically evaluated.
Interchangeability with other COVID19 vaccines
Pfizer-BioNTech COVID-19 vaccine is not interchangeable with other COVID-19 vaccines. The safety and efficacy of a mixed series have not been evaluated.
Persons initiating series with Pfizer-BioNTech COVID-19 vaccine should complete series with the same product.
If two doses of different mRNA COVID-19 vaccine products are inadvertently administered, no additional doses of either vaccine are recommended. Recommendations may be updated as further information becomes available or additional vaccine types authorized.
Coadministration with other vaccines
Pfizer-BioNTech COVID-19 vaccine should be administered alone with a minimum interval of 14 days before or after administration with any other vaccines.
If the Pfizer-BioNTech COVID-19 vaccine is inadvertently administered within 14 days of another vaccine, doses do not need to be repeated for either vaccine.
Persons with a history of SARS-CoV-2 infection
Vaccination should be offered to persons regardless of history of prior symptomatic or asymptomatic SARS-CoV-2 infection.
Viral or serologic testing for acute or prior infection, respectively, is not recommended for vaccine decision-making.
Persons with known current SARS-CoV-2 infection
Vaccination should be deferred until recovery from acute illness (if the person had symptoms) and criteria have been met to discontinue isolation.
No minimal interval between infection and vaccination. However, current evidence suggests reinfection uncommon in the 90 days after the initial infection. Thus, persons with documented acute infection in the preceding 90 days may defer vaccination until the end of this period if desired.
Persons who previously received passive antibody therapy for COVID-19
Vaccination should be deferred for at least 90 days to avoid the treatment with vaccine-induced immune responses. Based on the estimated half-life of therapies and evidence suggesting reinfection is uncommon within 90 days of initial infection.
Will the vaccine work against new virus variants?
Researchers are scrambling to make sense of the new variants. The latest research suggests that Pfizer’s COVID-19 vaccine will be protective against a mutation found in the two more-contagious variants of the coronavirus that have erupted in Britain and South Africa. Other vaccines are being tested. Dr. Anthony Fauci said that the coronavirus variants don’t appear to block vaccine-induced antibodies but that testing needed to be sure is underway in the U.S. and elsewhere. Likewise, British scientists have said the variant found in the U.K. – which has become the dominant type in parts of England — still seems to be susceptible to vaccines.
Which vaccine is better?
The Pfizer/BioNTech vaccine is authorized for ages ≥16 years and Moderna’s for ≥18 years. Aside from this age difference, there is no target population better suited to one vaccine or the other. In these times of limited supply, we are advising our eligible patients to get the vaccine that’s made available to them. It has already become common for people to ask others about which vaccine they have received, but the efficacy and safety findings in trials of both vaccines were strikingly similar. However, once the vaccine series has started, it should be completed with the same vaccine on the recommended schedule. There are no safety or efficacy data on using one vaccine for the first dose and a different vaccine for the second.
Should a patient who is diagnosed with Covid-19 shortly after the first dose still receive the second scheduled dose?
The vaccine begins to generate protective immunity 10 to 14 days after the first shot. As a result, it is not surprising that some people have experienced Covid-19 shortly after their first immunization, and they naturally wonder whether they should proceed with the second shot as originally scheduled. The current recommendation is that people with current infection should wait until they have recovered from the acute illness and are eligible to discontinue isolation. These recommendations apply both to those who developed Covid-19 before their first injection and to those who developed it after starting the vaccine series. On the basis of this guidance, some people in the latter group may be able to proceed with their scheduled second shot and others will need to wait. Treatment of Covid-19 with either monoclonal antibodies or convalescent plasma should delay receipt of the vaccine by 90 days since these treatments could theoretically make the vaccine less effective.
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updated on 12/23/20
updated on 1/8/2021
updated 1/18/2021
Dr. Amar Singh, MD, and Dr. Poonam Singh, MD, are board-certified by the American Board of Internal Medicine and American Board of Obesity Medicine. They specialize in preventing, treating, and reversing chronic diseases using an evidence-based holistic approach. They are specifically interested in weight management, hormone re-balancing, and longevity. The American College of Physicians has recognized them as Fellows, FACP, for their excellence and contributions made to both medicine and the broader community. They enjoy teaching, volunteering, and advocating for their patients. Their mission is to share simple, effective, and proven strategies that lead to meaningful, sustainable, and long-lasting well-being.
