Your Questions Answered: Concerns About the Second Dose of AZ Vaccine

Q: Your Questions Answered: Concerns About the Second Dose of AZ Vaccine

Hello： <br>1. <br>If the interval between the two doses of the AZ vaccine exceeds the recommended time, it is usually not necessary to receive a booster dose. <br>However, it is still advised to complete the vaccination as soon as possible to enhance and prolong immunity. <br>Add

Consultation regarding the AZ vaccine?

Hello, doctor.
I am considering getting the second dose of the AZ vaccine, but I have a few concerns that I would like your help with:
1.
I received my first dose of the AZ vaccine in September of last year, which means it has been nearly 10 months.
I would like to know if a long interval between doses reduces effectiveness and if I need to get a booster.
I have read online that a longer interval of over 40 weeks may actually improve effectiveness; is this true?
2.
I have been experiencing some symptoms over the past six months, including inner ear imbalance, ear fullness, occasional dizziness, and insomnia.
Can I still receive the vaccine under these circumstances? Will it exacerbate or affect these symptoms? (I have had some basic blood tests done, which showed slightly low neutrophils and elevated lymphocytes.)
3.
Recently, it has been suggested that the COVID-19 virus may become more like the flu over time, meaning symptoms could become milder.
Given this, is there still a necessity to receive the second dose?
4.
There has been some controversy surrounding mRNA vaccines, particularly regarding potential long-term side effects.
Is the AZ vaccine associated with similar concerns?

Cai Xiansheng, 20~29 year old female. Ask Date: 2022/07/17

Dr. Lin Zhebin reply Family Medicine

Hello:
1.
If the interval between the two doses of the AZ vaccine exceeds the recommended time, it is usually not necessary to receive a booster dose.
However, it is still advised to complete the vaccination as soon as possible to enhance and prolong immunity.
Additionally, a sufficient interval between the two doses of the AZ vaccine is required for optimal antibody production.
According to the Ministry of Health and Welfare, it is recommended that the two doses be spaced at least 8 weeks apart, with an interval of 10-12 weeks yielding even better vaccination efficacy.
Although some studies suggest that a 40-week interval may be more effective, I believe it is more appropriate to complete the second and third doses as early as possible within the recommended timeframe.
2.
You can receive the vaccine even if you are feeling unwell; however, your discomfort may worsen for 2-3 days after vaccination.
Unless severe complications occur, there is no evidence that the vaccine causes long-term discomfort.
3.
Although the severity of COVID-19 infections has been decreasing, it is still recommended to get vaccinated.
This not only reduces the risk of infection and severe illness but also helps with post-infection sequelae.
4.
Current research on COVID-19 vaccines indicates that, unless severe complications occur, there is no evidence of long-term sequelae.
The vaccines are theoretically considered safe.

Reply Date: 2022/07/17

More Info

When considering the second dose of the AstraZeneca (AZ) vaccine, there are several important factors to take into account, especially given your specific health concerns and the timing of your first dose. Let's address your questions one by one.

1. Timing Between Doses: You mentioned that your first dose of the AZ vaccine was administered nearly 10 months ago. While it is generally recommended to receive the second dose within 8 to 12 weeks after the first, studies have shown that extending the interval between doses can lead to a stronger immune response. Some research suggests that intervals of up to 40 weeks may enhance efficacy, but this is still a developing area of study. However, it is crucial to complete the vaccination series as soon as possible to ensure optimal protection against COVID-19. Therefore, while you may not need to "catch up" if you are beyond the recommended interval, it is advisable to proceed with the second dose to maximize your immunity.

2. Pre-existing Health Conditions: You mentioned experiencing symptoms such as inner ear imbalance, ear fullness, occasional dizziness, and insomnia. While these symptoms may be concerning, they do not automatically disqualify you from receiving the vaccine. Vaccination can sometimes lead to temporary side effects, such as fatigue or mild flu-like symptoms, which could potentially exacerbate your existing conditions for a short period. However, there is no evidence to suggest that the vaccine will cause long-term worsening of these symptoms. It is always wise to consult with your healthcare provider before vaccination, especially if you have ongoing health issues, to ensure that you are in a suitable condition to receive the vaccine.

3. Necessity of the Second Dose: The notion that COVID-19 may become milder over time is based on observations of viral evolution and population immunity. However, the risk of severe illness, hospitalization, and long-term complications from COVID-19 remains significant, especially with the emergence of variants like Omicron. Vaccination is still crucial in reducing these risks. The second dose of the vaccine not only boosts your immune response but also helps in providing better protection against variants. Therefore, it is advisable to proceed with the second dose to maintain a robust defense against COVID-19.

4. Concerns About Long-term Effects: Regarding the potential long-term effects of mRNA vaccines and the AZ vaccine, current research indicates that serious adverse effects are rare. Most side effects occur shortly after vaccination and resolve within a few days. There is no substantial evidence to suggest that the AZ vaccine causes long-term complications. The benefits of vaccination, including protection against severe disease and hospitalization, far outweigh the risks of potential side effects. Continuous monitoring and research are ongoing to ensure vaccine safety.

In summary, it is generally recommended that you proceed with your second dose of the AZ vaccine, considering the potential benefits of enhanced immunity and the current public health guidelines. However, it is essential to discuss your specific health concerns with your healthcare provider to ensure that you are making the best decision for your individual circumstances. Vaccination remains a critical tool in controlling the spread of COVID-19 and protecting public health.

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