Question
Are vaccines against COVID-19 safe and how do we know?
1 August 2020. Related: All topics, COVID-19.
Answer
Yes, any authorised vaccine will also be very safe. We know this from the results of large studies, and from even wider use since.
For example, the Pfizer vaccine was first studied in more than 44,000 people. Since then, it has been used by tens of millions of people.
With vaccines, most side effects occur in the first six weeks. All approved vaccines will have studied thousands of people for at least this long. Often, any symptoms are very similar to the control or placebo group.
But within a few weeks of approval the Pfizer vaccine had been used by hundreds of thousands more. This is when reactions that are more rare can sometimes be reported.
In the UK this included two people who had a history of allergy reactions. This history was serious enough for them to always carry an adrenaline syringe. Both people were managed in hospital similar to other allergic reactions and they are both now well.
This led to only giving mRNA vaccines (Pfizer and Moderna) where there is medical support to treat allergic reactions.
People with a history of serious allergies should discuss the risks from an mRNA vaccine with their doctor. This includes to any of the listed ingredients in the vaccine, for example to polyethylene glycol. It is easy for even severe allergic reactions to be safely managed.
Other common allergies, including to medications, foods, inhalants, insects and latex, are not thought to increase allergic reactions to the mRNA vaccines. Please discuss the benefits vs risks with your doctor who knows your history.
In a similar way, shortly after the Moderna vaccine was approved in the US, there were several reports of reactions in people who had used facial fillers. This was in two people who had used facial cheek fillers within six months and one person who used lip filler two days after the vaccine.
All the reactions resolved after treatment with steroids and antihistamines. Responses to both Pfizer and Moderna vaccines in people who have used facial fillers should be prospectively tracked to understand how often similar reactions occur.
As facial fillers are commonly used to correct HIV-associated lipoatrophy, this might be a caution. In practice though, very few treatments are likely to have been available during 2020 because of COVID. Also, the main filler used in the UK for lipoatrophy (New-Fill) isn’t a permanent filler, but just regenerates collagen growth.
Other very rare reactions might still be reported. This is because even very large studies cannot include every type of medical history. Also, the studies mainly included people who were generally well and at low risk of COVID-19.
The seriousness of COVID-19 makes it much safer to have an effective vaccine even if rare reactions might happen. This includes for people with a history of allergies or past use of fillers.
It is probably not a good idea to use facial fillers immediately after a vaccine. Guidelines are likely to recommend this.
How do we know the vaccine is safe?
These vaccine are safe because studies showed there is a very low risk of serious side effects.
Compared to the very real risks from COVID-19, using the vaccine is much safer than not using it. This is known from research studies in tens of thousands of people. The studies recorded every side effect or any potential side effect.
Additional safety data comes after the vaccines are used outside of studies. This will include from people who were not included in the main studies. This led to a caution in people with history of serious allergic reactions (see next Q).
This answer was updarted in August 2021 from a question first posted in December 2020. It is one of more than 75 questions about COVID vaccines produced by and for people living with HIV.
Q&A on COVID vaccines: are they safe and effective?
https://i-base.info/qa/16330
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