How Do Scientists Know That Approved COVID-19 Vaccines Are Safe?

After one year, resulting in more than 1.7 million deaths and many lockdowns, many people are welcoming the news that COVID-19 vaccines are being released to the public. Comprehensive vaccination may mean that life may return to pre-epidemic normality, although this scenario depends on people’s willingness to get noticed.

Some people are concerned about vaccine safety in general, while others are particularly skeptical about the novelty and rapid turnaround time of COVID vaccines. We asked 14 experts in immunology, biostatistics, and vaccineology whether COVID-19 vaccines are safe.

Which COVID-19 vaccines have been approved and what does this mean?

Use of vaccines with all other drugs is not permitted unless a country has ‘approved’ them. This approval process is carried out by an independent agency for each country or group of countries.

It is administered by the FDA (Food and Drug Administration) in the United States, MHRA (Medicine and Healthcare Products Regulatory Agency) in the UK, and the European Union EMA (European Medicine Agency).

For anything to be approved by these agencies, it has to be shown that it is 1) safe and 2) does what it is meant to do.

There are several COVID-19 vaccines currently in research and development. Although some of these are already in use in Russia and China, only two vaccines are currently approved for use in the United States and Canada.

One is a joint effort of Pfizer and BioNTech called ‘BNT162b2’ and one manufactured by Modern and called ‘mRNA-1273’. BNT162b2 has been approved in 9 countries around the world including the UK, and is also authorized by the EMA.

How is the vaccine approved?

For Pfizer and Modern vaccines to be approved by the above agencies, they may have proven themselves to be safe. The safety data to be examined during the approval process covers every stage of the vaccine’s journey, from initial experiments in the laboratory to the manufacturing process.

An important part of this data is clinical trials. All drugs, including vaccines, pass through three clinical trial stages:

  • Stage I ~ Test the vaccine on a small group of volunteers (20–80) so that it can be safely tested and the correct dose can be found.
  • Stage II ~ Find out if the vaccine actually works by dividing 100–300 volunteers into two groups and giving one group the vaccine and the other group a placebo.
  • Phase III randomly divides ~ thousands of volunteers into a vaccine group and a placebo group. Do not tell volunteers or doctors which group (this test is called ‘double-blind’) and check if the vaccine is working and if there are any side effects.

If a test is not successful, for example, the results indicate that the vaccine is not actually preventing the disease or causing its adverse effects, then the test is stopped, and the vaccine is not approved.

Even once the vaccine is approved, it passes on to stage IV, where it continues to be monitored and information on adverse effects is collected. It is important to establish whether there are very rare effects, for example in 1 in 100,000 chance.

For example, an allergic reaction to the Pfizer vaccine occurred after two people were given thousands in the UK. It also sometimes occurs in response to a flu vaccine, and health workers are prepared to handle such reactions when they give the jab.

Both people have fully recovered, but it is useful to collect information on this, for example the UK has now issued precautionary advice to those who have dangerous allergies.

Dr. of the University of Pittsburgh Olivare Finn states that “they continue to be widely distributed after all new vaccines continue to be monitored. We are now well connected throughout the world so the same problem with the vaccine anywhere in the world is the rapid examination. Will indicate. And change if warranted. “

What are the security data?

Both Pfizer and Modern vaccines have gone through all three clinical trials and no serious side effects have been found from their vaccines.

For the Pfizer vaccine, 195 people were recruited to the USA-based Phase I trial and 456 were included in the Germany-based Phase II trial. In both tests, no person receiving the vaccine suffered any serious side effects. Pfizer’s Phase III trial has been published in a peer-reviewed journal and featured more than 40,000 volunteers in 152 sites worldwide.

In this test, the volunteers were divided into two groups. One group was given two placebo jabs 21 days apart, and one group was given actual vaccine jabs. This means that eventually 18,566 people received the full 2 ​​doses of the vaccine.

All 18,366 volunteers were surveyed for 14 weeks after the second week and assessed for side effects, with blood samples taken. After the second jab, only 0.8 percent of them had fever. The more common symptoms at the injection site were soreness and sometimes muscle and headache.

Mayo Clinic professor Rick Kennedy explains that “the majority of the side effects seen were expected and are a direct result of the immune response to the vaccine. Side effects have been seen with other licensed vaccines and ores. At similar rates and With similar levels of severity (mostly mild and moderate). “None of the studies had a severe reaction to the vaccine.

An important factor is that this phase III study included people from diverse backgrounds: 49 percent female and 37 percent black, African-American or Hispanic. On top of this, the study included people who may be at high risk levels: 35 percent of the participants were obese, 21 percent had at least one concomitant condition, and the average age of the volunteers was 52.

The modern vaccine included 120 people in its Phase I trial and 600 in its Phase II trial. Although not all Phase III figures are yet available to the public (access to approved agencies), it includes 30,000 people from diverse demographics and has not seen any serious side effects.

All of the above information is freely available for anyone to read. On top of this, the regulatory agencies approving these two vaccines had access to much data that covers not only clinical trials but laboratory and animal studies. This information is often longer than 10,000 pages and is carefully scrutinized by the FDA, MHRA and EMA.

What is COVID vaccines?

Both Modern and Pfizer vaccines are RNA vaccines. RNA is information inside the SARS-CoV-2 virus that codes for all virus machinery.

Traditional vaccines use a dead or modified version of the virus that creates an immune response in the body, so it learns to recognize the virus and therefore becomes immune. RNA vaccines instead use a modified version of the SARS-CoV-2 virus RNA.

When RNA enters your cells, your cells form their own virus fragments, which then teach your body to become immune like any other vaccine. RNA by itself is not harmful, in fact your cells make and use RNA all the time.

As La Jolle Institute for Immunology Professor Kratty explains, “At any given time a human cell contains 5,000+ different RNA messages, and they are all temporary messages, such as these are post-notes that are written by cells after minutes or hours Burst. Read. “

RNA from the vaccine breaks down within a day of injection. Crucially, vaccines contain only a small fraction of RNA, “RNA message is for a single corevavirus virus. It takes 25 different coronavirus proteins to form a coronavirus, so someone about RNA making a virus Don’t worry. “

RNA is packaged into small balls of fat called lipid nanoparticles. These lipids are broken down and eliminated by your cells. Other elements to keep these particles stable are water and some salts and sugars.

This technique of delivering RNA by lipid nanoparticles has not previously been used for vaccines. However, the drugs that lipid nanoparticles (called ‘edic nanomedicines’) have been in use since the 1990s, and to date, more than 20 different people have been approved by the FDA or EMA. Some of these drugs are RNA-based, similar to RNA vaccines. They are commonly used for cancer and gene therapy.

How were vaccines made so soon?

Typically, vaccines take years to develop and manufacture. COVID-19 vaccines took less than a year. This is due to several reasons, three of which have been explained by Dr. Robert Carnahan of Vanderbilt University Medical Center:

“One, all vaccines … were manufactured ‘at risk’. This means that they were being produced before clinical trials were completed. This would never happen in normal condition. Many of these costs The support was carried out by various government organizations. Therefore, immediate that emergency approval was secured, delivery could begin.

Second, vaccine developers were increasingly analyzing data as they emerged in real-time for various regulatory agencies. Due to these activities alone there are often months of intervals between different stages of clinical trials.

Third, recruitment in clinical trials is often a slow and laborious process. People have to be ‘at risk’ for the disease in many different demographic and health categories. Due to the huge scope of the epidemic, it was faster to find adequate and appropriate volunteers. “

Importantly, the motion did not affect the clinical trials and safety aspects of the procedure: “The size, completeness, and complexity of clinical trials conducted for current COVID-19 vaccines did not differ from traditional clinical trials. These Equally safe. Vaccines and interventions developed at very slow timelines. “- Dr. Carnahan says.

Risk balance

Nothing in medicine is 100 percent safe – you do not take medication for a disease that you do not have or a vaccine against a disease.

Dr. of the global non-profit public health organization PATH. William Hausdorff explains that “all discussions of ‘safety’ for vaccines (or medicines in general) begin with how severe and persistent the condition you are trying to prevent or treat is. . If the situation is very minor, even trivial side effects may not be worth it. If the condition is very serious, people will accept a lot of potential side effects “.

Each medical intervention is a balance of risk versus benefit. Both Pfizer and Moderna vaccines have shown> 90 percent efficacy in protecting people from COVID-19 in their Phase III clinical trials. This protection from a virus that has caused the deaths of over 1.7 million people globally so far when thinking about vaccine safety.


All 14 experts agreed with the scientific consensus that COVID vaccines that have been approved by the appropriate regulatory agencies such as the FDA are safe in the form of another vaccine or drug.

Nothing in medicine is risk-free and the decision to take the vaccine is personal and is dependent on a person’s personal circumstances.

Article based on 14 expert answers to this question: Are COVID-19 vaccines safe?

This expert feedback was published in partnership with independent fact-checking platform Subscribe to their weekly newspaper here.


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