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Vaccine Adverse Events

Updated: Mar 9, 2022

Dr Victor Luca, 28-Feb-22

This is a response to a letter-to-the-editor by Brigid Kawe published in The Whakatāne Beacon of Friday 25-Feb-22.

Ms Kawe has taken a swipe at me for not being impartial in my writings regarding certain aspects of the pandemic.

First, she pulls me up on the statement I made ‘That for two years now I have been writing on all aspects Covid-19 pandemic’. I confess that this was a hyperbolic statement, because obviously, no single person could write on all aspects of such an immense public health event. Let’s just say that I have written on MANY aspects of the pandemic.

Ms Kawe raises many issues which obviously cause her serious concern and she asked for a response. Here I will address only some of the mentioned concerns since the Beacon doesn’t give me unlimited space to go into detail. I would however be happy to meet up and discuss the other issues raised whenever she wishes.

Onwards and upwards.

Most of what I have written has been distillations of the current science of this pandemic in which I try to put into lay terms material I source mostly from the current academic medical science literature. What readers do not see in all of my writings are the pages and pages of notes and references to research articles that accompany each piece I write.

Putting the search term ‘COVID’ into a bibliographic search engine such as Scopus (subscription only) today yields more than 274,000 scientific papers on this disease. These are not newspaper and magazine articles or facebook and other blog posts, they are highly technical peer-reviewed papers that are not easy to read, especially if you don’t have any training in relevant fields.

I am a research scientist, a chemist (not a pharmacist), and have done a considerably amount of research in many different scientific areas including the synthesis and characterization of nanoparticles of different types including those that are similar to the lipid nano-particles Pfizer uses to deliver mRNA into cells. These lipid nanoparticles are made from ionizable cationic lipids, phospholipids, cholesterol, and polyethylene glycol (PEG) that form a stable lipid bilayer.

I have also conducted considerable research with aerosols and in the nuclear medicine area. I am not a medical science specialist but I can make my way around many of the papers and understand and critically read the scientific literature. I have dedicated thousands of hours to bibliographic research on this pandemic.

A scientific paper is supposed to present new information/knowledge; it must be accurate and truthful, interpret data correctly and pass rigorous peer review. That is not to say that every paper that is published is perfect; mistakes are certainly made. And every so often the odd scientist falsifies results in pursuit of fame and glory. This is the case of the now totally discredited Dr Andrew Wakefield who shamefully falsified data connecting autism to the MMP vaccine. I guess scientists are after all only human.

By publishing your work in a scientific journal you provide others the opportunity to check, reproduce and re-interpret your work. This process can be iterative and lengthy until scientists converge on a solution to a problem. Keeping up with the science literature has been a life-long dedication and an occupational hazard. The process of doing starts always starts with a comprehensive grasp of the state of knowledge and that is gained in the library.

Science literature aside, there is of course a lot of other Covid-related writing out there that I do not read, I cannot. For instance, journalists, some with science training and others without, are able to access the science literature and can report information to the public in a more user-friendly manner.

Ms Kawe asks why I have not written about ‘Pfizer papers documenting the first 90 days of vaccine use, papers the FDA was hoping to hide for 55 years’.

It is difficult to determine exactly what Ms Kawe is referring to since she did not provide a citation to source material and so I assume she is not talking about the fact that vaccine immunity starts to wane after the first 90 days. Rather, I suspect that she is referring to the adverse events that Pfizer has tracked since authorization. Agencies such as the US Centers for Disease Control and Prevention’s (CDC) and the Food and Drug Administration also track these data via their Vaccine Adverse Event Reporting System (VAERS).

Here at home Medsafe, of course, keeps NZ’s own Adverse Events Following Immunization (AEFI) database. For the Pfizer vaccine up to 31-Jan-22 there have been a total of about 51,694 AEFI with 90% of the eligible population vaccinated or about 4.59 million people (∼1% AEFI, Pfizer). Of the total AEFI, 49,263 were non non-serious and 2,447 were classified as serious (∼0.05%). The most common side effects by far are head ache, dizziness, lethargy, infection site pain, nausea in that order. The CDC’s adverse events database is similar. Vaccine adverse events can be lodged by anyone and therefore can give a distorted view of vaccine safety. Interpretation of adverse event data requires great care.

I presume that when Ms Kawe refers to ‘reports’ she means reports such as ‘5.3.6 Cumulative Analysis of Post-authorization Adverse Event Reports’. This document was among the first tranches of documents released under Freedom of Information request she refers to. I have read this difficult to understand document and I find that the conclusion that the surveillance data ‘support a favorable benefit : risk profile of the BNT162b2 vaccine’ is justified. Balancing risk and benefit is an important consideration for any medication or vaccine.

Another question Ms Kawe has asked me to answer is ‘why are all Pfizer vaccines batches not equal’ in terms of adverse events? Here she makes an assertion that vaccine batches are not all the same and that this is responsible for variations in terms of AEFIs. She once again provides no specific citation for where she gets this information.

Although it is hard to respond without specifics let us consider the biochemical/chemical manufacturing process involved. I have spent a lifetime at a lab bench and reproducibility is something every experimental research chemist struggles with when it comes to the implementation of complex chemical processes. The more complex a chemical processes is, the greater the need to finely control all variables, such as for instance the purity of reactants (ingredients) and the process conditions (temperature, time etc). It is a little bit like baking a cake only much more complex. How many times when baking a cake using a given recipe does it always come out EXACTLY the same? And even if the cakes produced from a given recipe are not exactly they are nonetheless pretty close and quite fit for consumption. In the case of the Pfizer vaccine I expect that the company will be conducting extensive quality control by say checking the chemical characteristics of the finished product at least at the batch level.

So yes, all batches of Pfizer vaccine may not be EXACTLY the same down to the last molecule. Indeed, no two manufactured objects can ever be made identical, be they two cars, computers, light bulbs, a lump of metal or whatever. But variability does not necessarily mean a defective product.

This is why batch numbers are always registered and included on the vaccine vials. This enables those overseeing the manufacturing process to trace back in case a problem is suspected. Batch-to-batch variation in adverse events can have all sorts of reasons that may have less to do with the composition of the vial than other factors. For instance not all population demographics are the same.

Given the stringent measures taken to ensure batch integrity and quality when synthesizing a vaccine, I think that the probability of significant variations in AEFIs due to vaccine batch-to-batch variations must be low. However, it cannot be ruled out a priori that a particular batch out of the many millions made, or even a particle vial from a batch, has a variation outside an acceptable range. Like much of the subject matter that Ms Kawe has raised, this subject is not simple and interpretation has to be undertaken with care.

At the end of the day, the vaccines work well, they are highly effective, safe and relatively durable and when all is said and done they will likely have saved millions of lives. If you are vaccinated the data clearly show that you have a significantly reduced risk of death. There is also strong scientific evidence that you are less likely to transmit the virus to others if you are vaccinated.


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Barda, B. et al., Safety of the BNT162b2 mRNA Covid-19 Vaccine in a nationwide setting. NEJM 2021, 385, 1078.

Harder et al., Efficacy and effctiveness of COVID-19 vaccines against SARS-CoV-2 infection: interim results of a living systematic review, 1 January to 14 May 2021. Eurosurv. 2021, 26(28), 2100563.

Krantz, M.S., Phillips, E.J. COVID-19 mRNA vaccine safety during the first 6 months of roll-out in the USA. The Lancet 2022, DOI:

Omer, S.B. The discredited doctor hailed by the anti-vaccine movement

Riveting biography of Andrew Wakefield is a cautionary lesson in the legacy of hubris. Nature 2020, 586, 668.

Prunas et al., Vaccination with BNT162b2 reduces transmission of SARSCoV-2 to household contacts in Israel. Science 2022, DOI: 10.1126/science.abl4292

Rosenblum, H.G. et al. Safety of mRNA vaccines administered during the initial 6 months of the US COVID-19 vaccination programme: an observational study of reports to the Vaccine Adverse Event Reporting System and v-safe. The Lancet, 2022, DOI:

Yu, Y.B., Taraban, M.B. Briggs, K.T. All vials are not the same: Potential role of vaccine quality in vaccine adverse reactions. Vaccine 2021, 39(45), 6565–6569. doi: 10.1016/j.vaccine.2021.09.065

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