In most cases, having a reaction is still a good thing, health experts say.
Moderna and Pfizer/BioNTech vaccines are both vaccines with the potential for side effects. The second dose of Pfizer and Moderna vaccines may cause more noticeable side effects.
In clinical trials of these two vaccines, many participants experienced symptoms such as headache, fever, and body aches after the second dose. The main cause is believed to be an immune system response. with vaccines.
If the injector has never been infected with Covid-19 and receives the first dose of the vaccine, the virus that the vaccine causes the body to produce is completely new.
What technology do famous Covid-19 vaccines in Vietnam use?
The body of the injector will recognize this as an antigen and initiate a response with inflammation at the injection site. This is why the first dose often causes pain in the arm being injected.
By the second dose, the injected human body already has a certain amount of antibodies and some cells “remember” the spike protein from the first dose.
When detecting them again, the body will react more strongly and extremely quickly. As a result, the injector may develop many flu-like symptoms. This is when the body begins the process of producing more antibodies, helping to protect the person receiving the injection in the future.
For people who have never been infected with Covid-19, the first dose will activate the immune system and the second dose will act as a booster dose. For those who have been infected with Covid-19, the first injection acts as a booster because their body has activated the immune system when infected. In this case, the first dose will make them feel more tired than the second dose.
How effective is Pfizer’s Covid-19 vaccine?