Why side Effects Worse After the Second Shot? چرا عوارض جانبى واكسن كرونا در دفعات بيشتر ميشود

Why Are Pfizer and Moderna Vaccines’ Side Effects Worse After the Second Shot?

به نام خداوند بخشاينده ترين مهربان ترين

خدايا شكرت كه اين ٣٠ ساعت گذشت ديروز ٣١ دسامبر ٢٠٢١ دوز واكسن چهارم كرونا خود را زدم در ظرف ٦ ماه اخير اين واكسنها را زدم سينوفارم فايزر سينوفارم آنفلانزا فايزر حدس ميزدم كه عوارض جانبي دوز چهارم كرونا خيلي زياد باشد بخصوص اينكه چهار دوز را در فاصله كمتر از ٦ ماه زده ام بعد از زدن دوز آخر تا ساعت ١ شب هيچ عوارضى نداشتم تا اينكه براى خوردن آب پا شدم سه دقيقه بيشتر طول نكشيد كه تب و لرز شديدى گرفتم ده دقيقه بعد تبم به ٤١ درجه رسيد و احساس نزديكي به مرگ بهم دست داد با خودم گفتم با هر دوز نزديك عوارض جانبى بيشتر ميشود و اين طبيعى است ولى انقدر عوارض شديد بود كه شك كردم شايد همزمان كرونا گرفته باشم تجربه جالبى بود چون فهميدم آنها كه كرونا ميگيرند چه به آنها ميگذرد الان ٣٠ ساعت از تزريق واكسن فايزر ميگذرد سر دردم از بين رفته چشمانم را ميتوانم باز كنم و تبم از ٤١ درجه به ٣٨ درجه رسيده و اين مقاله زير به شما توضيح ميدهد كه چرا دوزهاى بعدى ميتواند كمى سختر و با عوارض بيشتر باشد

Many people have wondered why they have more intense side effects after getting the second shot of the Pfizer or Moderna COVID-19 vaccine. This phenomenon has to do with how vaccines help your immune system fight off infection.

We’ll take a look at how the immune system responds to vaccines, what the Pfizer and Moderna vaccine side effects are, and why they tend to be worse after the second shot.

Which COVID-19 vaccines require a second dose?

Both the Pfizer and Moderna COVID-19 vaccines require two doses. For the Pfizer vaccine, you need to wait 21 days after the first dose to get the second dose. For the Moderna vaccine, you need to wait 28 days. For both vaccines, you need both doses to be fully vaccinated. 

The FDA has also authorized a third COVID-19 vaccine dose for select individuals with lower immunity and people over age 65. A third dose is not currently required in other people who are fully vaccinated. For more information on who currently should receive a third dose, click or tap here.

The Johnson & Johnson vaccine is a single shot. However, new data suggests a second dose of this vaccine can help provide additional protection against COVID-19.

Pfizer and Moderna side effects after the second COVID-19 vaccine shot

The Pfizer and Moderna COVID-19 vaccines are the same type of vaccine — called messenger RNA(mRNA) vaccines. Because of this, you may experience similar side effects with either brand, but they may be more noticeable after the second shot. Common side effects can include: 

  • Arm pain, swelling, or redness

  • Headache

  • Fatigue

  • Body aches

  • Fever

  • Chills

  • Nausea  

More serious side effects, like a severe allergic reaction and myocarditis (heart inflammation) or pericarditis (heart lining inflammation), are very rare.

How many people experience Pfizer and Moderna side effects?

Most people may experience at least one side effect after getting their dose — the most common being an injection site reaction (e.g., pain, swelling, or redness). In the first few months after the Pfizer and Moderna vaccines were authorized, 70% to 75% of people reported this side effect after getting either dose.

Additionally, 50% of people reported systemic side effects (e.g., fatigue, headache, or muscle pain) after their first dose, which jumped to about 70%after the second dose. 

Chills and fever, which were reported by only about 9% of people after their first dose, went up to about 30% after the second dose. Similarly, joint pain was more common after the second shot, going from about 9% (first dose) to 26% (second dose).

During the Pfizer and Moderna clinical trials, side effects were reported more frequently in younger people getting the vaccine. Below we’ll review a few other factors that might influence your likelihood of experiencing side effects.

Are some people more likely to have side effects from the Moderna and Pfizer vaccine?

Your immune system’s response to the vaccine will depend on your medical history and the type of vaccine. Several factors can affect how your immune system reacts to a vaccine, including:

  • Age

  • Sex

  • Body mass

  • Previous immunity

  • Vaccine formulation

  • The injection site

For example, infants and toddlers are less likely to have reactions at the vaccine injection site but more likely to develop a fever than adults.  And in some studies, women were more likely to report side effects to the COVID-19 vaccines than men. Nearly 80% of women reported adverse events versus about 20% of men.

When should I expect to feel side effects after my second shot?

Side effects may be different for different people — including the time it may take for people to experience them. But more people had side effects on the day after the second Pfizer shot, and within a day or two of the Moderna shot. 

Although less common, it’s possible that some people may not experience any side effects at all.

Why are Pfizer and Moderna side effects worse after the second shot?

The second dose of the Pfizer and Moderna vaccines is likely to cause more noticeable side effects. In both the Pfizer and Moderna vaccine clinical trials, more participants had symptoms like headache, fever, and body aches after the second dose. The effects tend to be more intense after the second shot because of the way your immune system responds to vaccines.

The Pfizer and Moderna COVID-19 vaccines are both reactogenic vaccines, which means they are likely to cause side effects. This doesn’t mean, however, that everyone will have side effects, or that the vaccine doesn’t work if it doesn’t cause side effects. Here’s a breakdown of how the vaccines produce an immune response and why the second dose typically results in stronger side effects. 

If you have never been exposed to COVID-19 and get your first shot of the vaccine, the virus protein that the vaccine causes your cells to produce — known as the spike protein — is new to the body. This protein is harmless and will not infect you with the virus. 

Your body recognizes the protein as an antigen, or something foreign, and starts reacting to it with inflammation at the injection site. This is why the first shot very commonly causes arm pain. 

The cells that cause inflammation in your arm after the vaccine also send signals that tell your body to create antibodies against the spike protein. This process can cause inflammation in other parts of the body, leading to headache, fatigue, and fever after the first vaccine shot for some people.

When it comes time for the second shot, your body already has some antibodies and some cells that “remember” the spike protein from the first dose. When those cells see it again, they recognize it and launch a stronger response very quickly. This response causes widespread inflammation that can lead to flu-like symptoms. The good news is that this process also creates many more antibodies to help protect you in the future. 

For those that have never been infected, the first vaccine primes the immune system and the second acts like a booster. For some that have already had COVID-19, the infection primes the immune system and the first shot may act like a booster. For these people, the first vaccine shot may cause more symptoms than for those who have not had COVID-19 before. 

Even if you have had COVID-19, the Centers for Disease Control and Prevention (CDC) still recommends getting fully vaccinated.  

How long do Pfizer and Moderna side effects last?

For most people, the side effects only last a couple of days. For example, the Moderna vaccine’s side effects last roughly 1 to 3 days for most people. 

If your symptoms last longer, get worse, or you develop new symptoms, like a cough, you should get medical care right away. 

What can I do to treat Pfizer and Moderna vaccine side effects?

For side effects like arm pain, cooling the area and moving or exercising your arm as much as possible can help reduce soreness. Keeping your arm still or tensing your muscle may make the pain worse. 

If you have symptoms like headache or fever, you do not have to treat them if they are mild. For more serious symptoms, such as a migraine headache or high fever, you can consider using over-the-counter medications like Tylenol or ibuprofen. 

These medications are safe to use after vaccination, but are not recommended for symptom prevention. Since we do not know exactly how these medications may affect the immune system response, experts advise against taking them before getting the vaccine.

Some people may not be able to take Tylenol or ibuprofen because of other medical conditions, so it is important to always talk to your provider before taking any medication.   

The best thing to do after your second dose of the vaccine is to get plenty of rest and drink fluids. Your symptoms should get better on their own within a couple of days. If your symptoms do not get better, get worse, or you develop new symptoms, call a healthcare provider.