Response to letter to the editor on analysis

ABSTRACT

Recently Hui Liu commented on a paper titled “Analysis on the risks of severe adverse events in rabies post-exposure prophylaxis and appropriate decision-making procedure“ and arose some questions on the paper. In this reply letter, we would like to address the questions to make the previous paper more clear.

KEYWORDS:

• Rabies
• vaccination
• adverse effects

We are glad that the reader¹ raised relevant questions on our paper², and we are willing to further address these questions. Before writing point-to-point replies, we would like to generalize the aim of our paper.

The purpose of our article was to describe a clinical phenomenon and our considerations when dealing with the adverse event, and share our train of thought. As indicated in the abstract, the study emphasized the importance of in-depth survey and analysis and implied the necessity to scientifically and properly choose the optimal vaccine for patients and appropriately provide treatment if AEs occurred. It must be mentioned that we did not aim to compare the safety between two kinds of vaccine. Such comparison needs a large-population study rather than a case analysis.

1. In China, each batch of vaccine should be attached with a Finished Products Test Report and a Certificate for the Release of Biological Products, to assure its eligibility to pharmaceutical market. The Regulation for Lot Release of Biological Products was issued by China Food and Drug Administration. (http://samr.cfda.gov.cn/WS01/CL0053/24488.html) This regulation was updated in 2017. (http://eng.sfda.gov.cn/WS01/CL0053/220852.html) However, there were details about manufacturers on test reports and certificates, so to avoid them being used beyond the scientific field and avoid misunderstanding of two kinds of vaccines, they were not provided along with our paper.

2. We did not realized this inaccuracy when we wrote the paper and we highly appreciate the reader for bringing it up. We admit that this specific expression in the paper was not precise. If antibiotics and other components irrelevant to antigen were within limits of detection, they would be shown “without” on the test report. However, there might exist trace amounts of such components and this was not equal to “without”.

3. It was indicated from a previously published paper³ that children aged under 5 years occurred less AEs when they were immunized with small-dose rabies vaccines. Since the specific patient in our paper had suffered from an AE, it was necessary to choose a relatively suitable kind of vaccine for her. We referred to the test report of both kinds of vaccines and found that it was regulated that kanamycin in HDCV should be below 20ng/dose and the concentration of kanamycin in that batch of vaccine was 6ng/dose. That batch of HDCV was eligible but individual variation lead to various sensitivity and therefore, a few persons had adverse events while others not. Unlike HDCV, PVRV was produced with vero cells, repeatedly passaged in sub-culture cells, and test items were focused on bovine serum albumin, DNA residues and protein residues. If a person was allergic to albumen, he/she would be better off to no to receive PVRV.

   We have to state here again that we do not tend to compare these two kinds of vaccines but share our clinical thinking.

4. Herein we need to clarify that corticosteroids were not applied during the resumed vaccination procedure. Corticoids were prescribed to the patient within two days after the AE occurred to relieve her anaphylaxis symptoms. When flushing and wheal rash gradually faded and her temperature went down to normal (36.8°C), corticsteroids was no longer provided to her.

Disclosure of potential conflicts of interest

No potential conflict of interest was reported by the authors.