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Taming the Enemy
Published in Norman Begg, The Remarkable Story of Vaccines, 2023
These attenuated vaccines (often referred to as live attenuated vaccines or replicating vaccines) have a number of advantages over inactivated vaccines. Because they are alive, they grow and multiply in your body. This means your immune system gets a continuous stimulus over several days or even weeks. Live attenuated vaccines provide stronger, and longer-lasting immunity than killed ones. Yellow fever is a live attenuated vaccine; a single dose will protect you for life. There are some downsides, however. The ability of live vaccines to multiply means that they can produce symptoms of the disease, albeit a much milder version. Measles vaccine is a good example. It’s quite common for a child to develop a rash and mild fever about a week after the vaccine; a “mini measles”. Very rarely, a live vaccine can produce a full-blown version of the disease. Paralysis following live polio vaccination (the version that is given by mouth) occurs at a rate of about one per 2 million doses. This is still much better than the actual disease, where up to one in ten people who are infected will get paralysis, however, it is one of the reasons why most polio vaccines given nowadays are the killed version, which cannot cause paralysis. Another drawback of live vaccines is that they cannot be given to people with severely weakened immune systems, as they may not be able to control the replication of the organism. Examples of live attenuated vaccines include measles, mumps, rubella, yellow fever, BCG (for tuberculosis) and oral polio vaccine.
The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
A variety of strategies are used to produce attenuated vaccines including adaptation to unnatural host species by serial passage in unnatural host animals or by serial passage in cell culture. Inactivated vaccines are made of whole virus or components of virulent viruses that have been physically or chemically modified to destroy infectivity. They are generally safe and provide protection, but often provide a shorter-lived immunity than do live attenuated vaccines. Commonly used agents to inactivate viruses in the preparation of a “killed” vaccine include formaldehyde, (β-propiolactone, and ethyleneimine.
Vaccinations
Published in Vincenzo Berghella, Maternal-Fetal Evidence Based Guidelines, 2022
Joshua H. Barash, Edward M. Buchanan
Several vaccines are available against SARS-CoV-2, the virus responsible for COVID-19 infections. COVID-19 infection is associated with higher incidence of hospitalization, mechanical ventilation, intensive care unit admission, maternal death, compared to COVID-19 in non-pregnant reproductive age women [60], and higher incidences of preterm birth, stillbirth, and other adverse perinatal outcomes, especially with critical COVID-19 infection [61]. The m-RNA vaccines (e.g. Pfizer, Moderna) are safe and should be recommended in pregnant women, in any trimester, as well as during lactation [62]. Withholding FDA-approved vaccines from this population based on theoretical risks would be unethical [62]. FDA-approved vaccines should not be withheld from women solely based on their pregnancy or lactation status when they otherwise meet criteria for vaccination [62]. Withholding vaccine violates ethical principle of autonomy, as well as beneficence and justice [62]. Live-attenuated vaccines should not be administered in pregnancy.
Weight of evidence evaluation for chemical-induced immunotoxicity for PFOA and PFOS: findings from an independent panel of experts
Published in Critical Reviews in Toxicology, 2023
Gregory J. Garvey, Janet K. Anderson, Philip E. Goodrum, Kirby H. Tyndall, L. Anthony Cox, Mahin Khatami, Jorge Morales-Montor, Rita S. Schoeny, Jennifer G. Seed, Rajeev K. Tyagi, Christopher R. Kirman, Sean M. Hays
The Faroe Island epidemiology data were rated with medium confidence.As described in Luster et al. (1992), Tier 1 assays include those for cell-mediated immunity, humoral-mediated immunity, as well as immunopathology, and are designed to demonstrate potential immunotoxic doses without inducing overt toxicity.During peer-review for publication, one reviewer suggested that the addition of pertussis to the booster vaccine be evaluated as a covariate. While this was not discussed by our panel, the authors agree that this is another potential covariate that should have been considered.One panel member abstained from rating the studies.Examples of live attenuated vaccines include these: measles, mumps, and rubella (MMR); varicella; polio. Examples of inactivated vaccines include these: tetanus, diphtheria, acellular pertussis (Tdap); human papilloma virus; meningococcus, haemophilus, pneumococcus, hepatitis A. Standard influenza vaccines vary depending on route of administration: inhaled vaccine is live; injected vaccine is inactivated (Anderson 2019).
Microfluidic production of mRNA-loaded lipid nanoparticles for vaccine applications
Published in Expert Opinion on Drug Delivery, 2022
Carolina Lopes, Joana Cristóvão, Vânia Silvério, Paulo Roque Lino, Pedro Fonte
NA-based vaccines include viral vectors, plasmid DNA and mRNA [8,9]. These therapeutics promote vaccine development against a wide range of pathogens, as they support the delivery of any antigen of choice, regardless of whether it is derived from bacteria, parasite, or virus, and their immune responses are focused only on the antigens of interest [9]. The mRNA vaccines have shown significant interest for the treatment against infectious diseases and several types of cancer. The use of mRNA-based vaccines has several benefits over conventional live attenuated and DNA-based vaccines. Because live attenuated vaccines show higher potency, there is an associated risk of reverting to a pathogenic form and cause infection. In comparison to DNA-based vaccines, mRNA therapeutics are easier to deliver as RNA only needs to be delivered into the cytoplasm of the host cell to be translated into protein. Also, mRNA therapeutics are safer since RNA cannot integrate his genome in the host cell. RNA exhibits shorter half-life, hence only a low level of expression can be achieved in vivo, resulting in a more controllable therapy in case of adverse effects. On top of all the above, mRNA vaccines allow rapid and easy development. Indeed, production of mRNA by a cell-free environment by in vitro transcription of a DNA template that contains the mRNA sequence avoids the use of microorganisms or cultured cells, allowing simple downstream purification and very rapid and cost-effective manufacturing [10].
Corneal Graft Rejection after Yellow Fever Vaccine: A Case Report
Published in Ocular Immunology and Inflammation, 2022
Roberto Vignapiano, Lidia Vicchio, Eleonora Favuzza, Michela Cennamo, Rita Mencucci
Live attenuated vaccines are generally contraindicated in patients with solid organ transplant and under immunosuppressive therapy, due to safety concerns.17 From the available evidence, we cannot conclude that live vaccines are completely safe in immunosuppressed patients. However, serious side effects or infections after some types of live attenuated vaccines such as mumps, measles and rubella (MMR), yellow fever, varicella (VV), herpes zoster (HZ), oral typhoid, oral polio, rotavirus, Bacillus Calmette-Guérin (BCG), and smallpox are extremely rare.18 Corneal transplants could represent a particular case of solid organ transplantation performed on humans. The success rate of orthotopic corneal allografts, in both humans and experimental animals, is related to the phenomenon of “immune privilege” by which inflammation is self-regulated to preserve ocular functions.19