The conversation / Reuters.- As the application of the Covid-19 vaccine begins this week in Australia, many people still have questions about their safety, both short and long term.
Vaccine experts address these concerns to The conversation all the time and they say that it is normal to have questions about it.
The good news is that scientists have already been testing Covid-19 vaccines for months. To get started, serious side effects are very, very rare. And, along with what we know about previous vaccines, if side effects are going to occur, they usually happen a few months after getting the vaccine.
This is the reason why international medical regulators, including the Therapeutic Goods Administration (TGA) of Australia, require the first few months of safety data before approving new vaccines. This, in addition to information from vaccine recipients in the northern hemisphere, Provides confidence that Covid-19 vaccines are safe.
In fact, most side effects occur during the first day or two. And most of these are mild, such as injection site pain, fatigue, or fever, which are signs that your immune system is developing a response against what it has been vaccinated against.
Since December, more than 200 million people have received at least one dose of the Covid-19 vaccine worldwide, more than the total number of people infected with the virus (112 million).
Given the large number of vaccines administered to date, common, uncommon and rare side effects would have already been detected. In addition, they have been testing these vaccines in clinical trials since mid-2020, and both the Pfizer and AstraZeneca vaccines have shown excellent safety results.
Some people have also been seen raising concerns online about mRNA vaccines, such as the Pfizer-BioNTech vaccine, which is a “new” technology. MRNA (or “messenger” RNA) is found in all living cells. MRNA is a message that tells cells how to make proteins that trigger immune responses within the body. That immune response is what protects against infection if a person is exposed to the virus.
MRNA is not the same as DNA (its genes) and cannot combine with our DNA to change our genetic code. The mRNA vaccines do not affect or interact with DNA in any way. Therefore, we can be sure that these vaccines they will not alter DNA in the long term.
Furthermore, verification of the safety of vaccines does not stop only after they have been registered for use. Once a vaccine has been introduced, continuous monitoring of its safety is a crucial part of the vaccine development process.
Australia has a robust system for this ongoing monitoring. The system was established to detect any unexpected side effects of vaccines (if they occur) and ensure they are investigated immediately. This type of monitoring is standard practice in Australia for vaccines.
The data on Covid-19 vaccination collected in these surveillance systems will be published weekly on the TGA website. This should reassure Australians that if there is a serious new side effect, it will be known, reported and acted upon quickly.
The withdrawal of vaccines after their introduction into the general population is a very rare event.
In the U.S, A rotavirus vaccine called Rotashield caused a small increase in the number of blockages in the small intestine. This led to its withdrawal in the late 1990s. In Australia, in 2010 An increased risk of febrile seizures was identified in young children after a specific influenza vaccine. It was later withdrawn from use in that age group and is now being given with a different and safer flu vaccine. This vaccine is no longer available in Australia and was subsequently reformulated.
Both side effects were seen within a few weeks of vaccination.
Monitoring systems in Australia have now improved to detect such serious side effects even earlier, in the general population after clinical trials, than a decade ago.
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Pfizer-BioNTech Covid-19 Vaccine
The expected side effects of the Pfizer vaccine have been reported from trials involving approximately 43,000 people aged 16 years and older from the US, Argentina, Brazil and South Africa. Half of the participants received the Pfizer vaccine and the other half received a placebo. And as part of the Covid-19 vaccine launches around the world, millions of people have already received this biological since December, which means that we now have safety data from both clinical trials and two months of vaccination in the “real world”.
For those who received this vaccine in the large clinical trials that began in July 2020, about 80% reported pain at the injection site. Other common side effects included fatigue, headache, muscle pain, chills, joint pain, and fever.
These were most frequently reported one to two days after the day of vaccination and generally only lasted about a day. While some vaccine recipients may need a day off from work due to some of these side effects, this does not indicate that the vaccine is unsafe.
In the trials, there were no differences in the rate of serious side effects between the Pfizer vaccine and placebo. At the beginning of the US program, 21 cases of anaphylaxis, a serious allergic reaction throughout the body, were reported. Anaphylaxis is estimated to occur at a rate of 11 out of every million recipients (0.0011%) of the Pfizer Covid-19 vaccine. Most occurred within 15 minutes, and all patients recovered. That is why It is a good idea to stay at the vaccination clinic for up to 15 minutes after vaccination so that treatment and care can be provided if needed.
Another concern arose in January, after the death of 30 very frail elderly patients in Norway after receiving the Pfizer-BioNTech Covid-19 vaccine. But the investigation by the European regulator concluded that these were not related to the vaccinebut with the underlying conditions present before vaccination.
Vacuna Oxford-AstraZeneca Covid-19
This vaccine has been tested in ongoing trials with around 55,000 participants from the UK, Brazil, South Africa, and the United States. About half received the Oxford-AstraZeneca vaccine and half a placebo. Millions of doses have already been administered to the general population, particularly in the UK.
Data from four clinical trials that began in April 2020 in the UK, Brazil and South Africa show that the most common side effects were injection site pain, fatigue, headache, and muscle pain. As with the Pfizer vaccine, there was no difference in the rate of serious reported side effects of the vaccine compared to placebo.
Only 0.7% of participants (79 people) in the four clinical trials who received the Oxford-AstraZeneca vaccine reported a serious side effect after receiving at least one dose, compared to 0.8% (89 people) of those in the placebo group. No additional safety concerns have been identified since the UK vaccination program began.
As countries continue to monitor those who have received vaccines, we must be sure that no major safety concerns have been detected so far due to serious side effects. With millions of people already vaccinated, our confidence in the safety of Covid-19 vaccines is very high.
In Australia, and internationally, robust systems are in place to continuously monitor vaccine safety, ensuring that everyone can enjoy the protection that Covid-19 vaccines are designed to provide.
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