Vaccinated but Infected: Breakthrough Cases After BNT Booster

Q: Vaccinated but Infected: Breakthrough Cases After BNT Booster

Hello： Although your boyfriend contracted the virus after receiving the third dose of the vaccine, the vaccine is still effective. <br>Both vaccination and infection with COVID-19 stimulate the production of antibodies in the body, and their effects do not cancel each other out.

Just got vaccinated and then contracted the virus?

My boyfriend just received his third dose of the BNT vaccine on May 26 (the first two doses were also BNT).
He developed a fever on the night of vaccination, and the fever persisted the next day.
We thought it was just a normal vaccine side effect and didn't pay much attention.
On the evening of May 28, he felt discomfort in his throat and decided to take a rapid test, which turned out to be positive.
We are unsure when he was infected.
Could you please advise if the third dose of the BNT vaccine is still effective under these circumstances? Thank you.

A Miao, 30~39 year old female. Ask Date: 2022/06/02

Dr. Lin Zhebin reply Family Medicine

Hello: Although your boyfriend contracted the virus after receiving the third dose of the vaccine, the vaccine is still effective.
Both vaccination and infection with COVID-19 stimulate the production of antibodies in the body, and their effects do not cancel each other out.
In the future, both will help reduce the risk of infection and decrease the severity of the disease, so there is no need to worry too much.

Reply Date: 2022/06/02

More Info

Breakthrough infections after vaccination, such as the case you've described with your boyfriend receiving the BNT (BioNTech) booster, are indeed a topic of significant interest and concern. It's important to understand that while vaccines, including the BNT vaccine, are highly effective at reducing the risk of severe illness, hospitalization, and death from COVID-19, they do not provide 100% immunity. Therefore, breakthrough infections can occur, even after receiving multiple doses of the vaccine.

In your boyfriend's case, he experienced typical side effects after receiving the booster, such as fever, which is a common response indicating that the immune system is reacting to the vaccine. The fact that he tested positive for COVID-19 shortly after vaccination does not mean that the vaccine was ineffective. Instead, it highlights a few key points about how vaccines work and the nature of viral infections:
1. Vaccine Efficacy: Vaccines are designed to prime the immune system to recognize and fight off the virus. While they significantly reduce the likelihood of infection, they do not eliminate the risk entirely. The BNT vaccine has shown high efficacy rates in clinical trials, but breakthrough infections can still happen, especially with the emergence of new variants of the virus.

2. Timing of Infection: It is possible that your boyfriend was exposed to the virus shortly before or after receiving the booster shot. The immune response takes time to develop fully, and while the vaccine helps prepare the immune system, it does not provide immediate protection. The incubation period for COVID-19 can range from 2 to 14 days, meaning he could have contracted the virus before the vaccine had a chance to build up sufficient immunity.

3. Immune Response: Even if a vaccinated individual contracts COVID-19, the vaccine can still provide a level of protection. Studies have shown that vaccinated individuals who do contract the virus often experience milder symptoms compared to unvaccinated individuals. This is because the immune system has been trained to respond more effectively to the virus due to the vaccine.

4. Continued Precautions: It is crucial to continue practicing preventive measures, such as wearing masks, maintaining physical distance, and practicing good hygiene, even after vaccination. This is especially important in areas with high transmission rates or when new variants are circulating.

5. Monitoring Symptoms: If your boyfriend is experiencing symptoms, it's essential to monitor them closely. While many breakthrough infections are mild, some individuals may still develop more severe symptoms. If symptoms worsen or if he has underlying health conditions, seeking medical advice is recommended.

In summary, your boyfriend's experience of testing positive for COVID-19 after receiving the BNT booster does not indicate that the vaccine is ineffective. Instead, it underscores the importance of understanding the limitations of vaccines and the need for continued vigilance against COVID-19. Vaccination remains one of the best tools we have to combat the pandemic, but it is not a foolproof solution. Encourage him to rest, stay hydrated, and follow any medical advice provided by healthcare professionals.

Similar Q&A

Is BNT Vaccine Safe for My Son with a History of Allergic Purpura?

My son is currently in the first year of junior high school and just turned thirteen. He experienced allergic purpura at the age of six, which has not recurred since then. The diagnosing physician mentioned that the cause of this condition is unknown. I have searched for informat...

Dr. Xiao Kaiwen reply Pediatrics
Allergic purpura is an autoimmune vasculitis characterized by inflammation of the blood vessels. The cause of the production of autoimmune antibodies is unknown, but it is speculated that it may be triggered by previous viral infections. However, if there have been no recurrences...

Medication Guidance After BNT Vaccination: Steroids and Oral Care

Hello doctor, I just received the BNT vaccine. Can I apply eczema steroids (Betamethasone) and mouth ulcer medication (Mondesil) that contains alcohol after getting the vaccine? Thank you. Also, if I experience severe mouth ulcers after the vaccination, does that indicate an issu...

Dr. Lin Wufu reply Internal Medicine
Hello: It is generally not recommended to use immunosuppressive medications after receiving a vaccine, so oral or injectable steroids are discouraged. However, topical ointments are absorbed in very low systemic doses, so they can still be used if necessary. Medications for mouth...

Can a 13-Year-Old with Myocarditis Safely Get the BNT Vaccine?

Hello, Doctor! I was diagnosed with acute myocarditis at the age of five and stayed in the intensive care unit for two weeks. It was suspected to be a viral infection, but no specific virus was identified. I have been following up at National Taiwan University Hospital for six mo...

Dr. Wu Xueming reply Cardiology
Please follow the vaccination guidelines provided by the Central Epidemic Command Center and consult with a vaccine specialist.

Can I Get the BNT Vaccine with a Sore Throat and Phlegm?

I have a slight sore throat and phlegm when I swallow. I am scheduled to receive the BNT vaccine this Wednesday. Is it safe for me to get vaccinated?

Dr. Hong Yuanbin reply Internal Medicine
Hello, it is recommended to first perform a COVID-19 rapid test. If the result is positive, it is advised to wait three months before getting vaccinated. If the result is negative and there is no fever on the same day, vaccination can proceed. Thank you for your inquiry.