Is the new crown vaccine allergic "accidental"? What is the impact on follow-up vaccinations?

A recent commentary published in the New England Journal of Medicine (NEJM) explores the allergic reactions and safety of the new crown vaccine.
authors are Dr. Mariana C. Castells of Brigham and Women's Hospital, Harvard Medical School, and Dr. Elizabeth J. Phillips of Vanderbilt University Medical Center.
in this article, we share the key points and related information.
existing safety signals The two experts first compared the allergic reactions of the two mRNA vaccines after clinical trials and the actual initiation of mass vaccinations.
in phase 1-3 clinical trials of the Pfizer/BioNTech and Modelna mRNA vaccines, people with a history of severe allergies to any vaccine were not included.
trials of both vaccines, placebo (physiological saline) and the vaccine group had similar rates of hypersensitivity adverse events.
minor local side effects, such as pain, redness and swelling, as well as systemic symptoms such as fever, fatigue, headache, muscle and joint pain, were more commonly observed after vaccination than with placebos.
after the Pfizer/BioNTech new crown vaccine launched mass vaccinations, allergic reactions were reported in both the UK and the US.
of these, two people in the UK are known to have a history of severe allergies from food and medicine, while the first allergy report in the US has no known allergic reaction, but none of the three inoculators were excluded from the trial, as designed by the trial.
Moderna's new crown vaccine has been granted emergency use later and allergy signals are still under observation, although very few cases of potential allergic reactions have been reported, including one case of medical personnel with severe allergies to shellfish.
Although it remains to be seen whether these adverse reactions are really vaccine-related, both the Uk Medicines and Health Products Administration (MHRA) and the FDA have issued further preventive recommendations to exclude people at risk of allergies.
the potential causes of vaccine allergic reactions, two experts noted that vaccine-related allergic reactions are still rare.
for most vaccines, the typical occurrence rate is one in a million.
allergic reactions can be treated with no long-term effects.
and, when vaccinated in millions of people, the safety signal is almost "inevitable."
but the news of the new vaccine clearly raised public concerns and highlighted the importance of understanding the mechanisms of allergic reactive pathogenes, identifying people at risk, and developing prevention and management strategies.
, there are more questions than we have to answer.
allergic reactions are caused by IgE's antigen binding and crosslinking activation of mast cells, and a range of symptoms due to tissue reactions caused by the release of media such as histamines, proteases, prostaglandins, and white triene.
patients are often sensitive to IgE because they have previously been exposed to antigens.
In addition, there is a non-IgE-mediated allergic reaction with similar clinical signs and symptoms, but occurs through direct activation, complement activation, or other mechanisms of fat cells and alkaline granulocytes, and may occur at the first exposure to antigens.
currently, some cases in the United States and the United States are clinically consistent with allergic reactions.
after vaccination may be caused by vaccine antigens, residual non-human proteins or preservatives, and stabilizers in vaccine preparations.
but historically, allergic reactions mediated by IgE have often been associated with inactive ingredients in vaccines.
Pfizer/BioNtech and Moderna's mRNA vaccine uses lipid nanoparticles (LNP) technology, which helps prevent the degradation of mRNA in the body and facilitates delivery.
polyethyl glycol (PEG) is used in this lipid nanoparticle technology.
although mRNA technology has been developed for many years, no mRNA vaccine has been approved for clinical use before, so there is no previous experience that could provide a potential explanation for the mechanisms of mRNA-related allergic reactions.
studies of other drugs suggest that PEG may be a rare cause of allergic reactions, but so far no other vaccines that use PEG as an exfusion agent have been widely used, making it difficult to provide historical references.
part of the new crown vaccine may cause an allergic reaction? Are there any vaccines that are less likely to cause allergic (like) reactions to IgE or non-IgE mediated? more research is needed to answer.
this have an impact on mass vaccination? Recently, on the Metalact platform, 14 experts from the world's top medical academic and public health institutions agreed that there is no absolute "zero risk" in medicine, based on the results of public trials of several vaccines, as well as approval by different regulators, overall, the new crown vaccine approved can be considered safe.
given the epidemic and the protective power shown by vaccines in trials, existing approved vaccines have a good benefit-risk ratio.
In this NEJM article, the two experts also stressed that, like any other treatment that is urgently authorized for use, it is not surprising that adverse events are not observed in clinical trials in practice;
But back to the above allergy question, whether being allergic to one vaccine means being allergic to another vaccine is still unknown; the formulation of the adenovirus vector vaccine usually contains polysorbital esters similar to PEG structures as surfactants and emulsions, and there is no answer as to whether there is a potential effect.
the CDC currently recommends that all individuals with a history of allergic reactions to the mRNA new crown vaccine, as well as patients with a history of PEG-related acute reactions, avoid these vaccines until more information is available in the industry.
recommendations will help maintain the safety of existing new crown vaccines and future new crown vaccines with similar ingredients, according to a commentary.
vaccines have entered a new critical phase in outbreak prevention and control, and several more vaccines are likely to be available for clinical use in the coming months.
important is to develop strategies to improve the effectiveness and safety of mass vaccinations, such as enhanced post-vaccination monitoring and documentation.
addition, the two experts offered more far-reaching considerations: on the one hand, the new crown vaccine still has a lot of questions to answer, such as how long immunity can last after vaccination, and whether it can limit the spread of the virus. On the other hand, mRNA vaccines are promising new technologies that demonstrate their safety and are relevant for several other antiviral vaccines that affect the world, as well as for the development of many cancer vaccines.
new crown vaccine is undoubtedly an important weapon in the global fight against the epidemic.
we also look forward to more data accumulation that will give us a deeper understanding of vaccine protection and safety.
References, Mariana C. Castells, Elizabeth J. Phillips. (2020). Maintaining Safety with SARS-CoV-2 Vaccines. N Engl J Med, DOI: 10.1056/NEJMra2035343 [2] How Scientists Know The Approved COVID-19 Vaccines Are Safe. Retrieved January 4, 2020, from。