Which live vaccines

Some bacteria cause disease. They will grow in a vaccinated individual, but because they are weak, they will cause no or very mild disease.

LAVs stimulate an excellent immune response Immune response The body's defense against foreign objects or organisms, such as bacteria, viruses or transplanted organs or tissue. Live microorganisms Microorganisms Tiny organisms including bacteria and viruses that can only be seen with a microscope. In the case of viruses or intracellular microorganisms where cell-mediated immunity Cell-mediated immunity An immune response not involving antibodies, in which specific blood cells, leukocytes, and lymphocytes attack and remove antigens.

Since LAVs contain living organisms, there is a degree of unpredictability raising some safety and stability concerns. The table lists the rare, more severe adverse reactions of these vaccines. Note the frequency of the adverse reactions to get an idea of how low or high the possibility of an adverse event is. Also read the Comments to understand additional context details on the adverse events. Answer B : Allergic anaphylactic reactions are more likely to occur after receipt of the second dose of measles vaccine.

Answer C : Pertussis wP is an inactivated vaccine. Live vaccines include:. Immune response LAVs stimulate an excellent immune response Immune response The body's defense against foreign objects or organisms, such as bacteria, viruses or transplanted organs or tissue. Safety and stability Since LAVs contain living organisms, there is a degree of unpredictability raising some safety and stability concerns. Attenuated pathogens have the very rare potential to revert to a pathogenic form and cause disease in vaccinees or their contacts.

Examples for this are the very rare, serious adverse events of: vaccine-associated paralytic poliomyelitis VAPP and disease-causing vaccine-derived poliovirus VDPV associated with oral polio vaccine OPV. Functional immune systems eliminate attenuated pathogens in their immune response. Individuals with compromised immune systems, such as HIV-infected patients may not be able to respond adequately to the attenuated antigens.

Sustained infection, for example tuberculosis BCG vaccination can result in local lymphadenitis or a disseminated infection. If the vaccine is grown in a contaminated tissue culture it can be contaminated by other viruses e. Theoretically, live attenuated virus vaccines given to pregnant women might be capable of crossing the placenta and infecting the foetus.

As a result, most live attenuated vaccines are contraindicated or not recommended during pregnancy. Other types of vaccines are allowed during cancer treatment. They can be naturally occurring or synthesized through the individual expression of viral structural proteins, which can then self-assemble into the virus-like structure. In some cases, the antigens in a VLP vaccine are the viral structural proteins themselves.

Alternatively, the VLPs can be manufactured to present antigens from another pathogen on the surface, or even multiple pathogens at once.

As each VLP has multiple copies of an antigen on its surface it is more effective at stimulating an immune response that a single copy. In some cases, the structural proteins of the VLP can act as adjuvants, helping to strengthen the immune response to the primary target antigen. Outer Membrane Vesicles OMVs are naturally produced by bacteria and are essentially a bleb of the bacterial outer cell membrane.

This contains many of the antigens found on the cell membrane but is a non-infectious particle. In the lab these OMVs can be harvested from bacteria to use as vaccines. The OMVs can also be modified so that toxic antigens are removed and antigens suitable for stimulating an immune response can be kept. OMVs also naturally act as adjuvants. This is a newer vaccine technology so there are few licenced examples:. Design by Ben Leighton. Nucleic acid vaccines work in a different way to other vaccines in that they do not supply the protein antigen to the body.

Instead they provide the genetic instructions of the antigen to cells in the body and in turn the cells produce the antigen, which stimulates an immune response. Nucleic acid vaccines are quick and easy to develop, and provide significant promise for the development of vaccines in the future.

This fatty cover both protects the mRNA when it first enters the body, and also helps it to get inside cells by fusing with the cell membrane. Once the mRNA is inside the cell, machinery inside the cell translates it into the antigen protein.

This mRNA typically lasts a few days, but in that time sufficient antigen is made to stimulate an immune response. It is then naturally broken down and removed by the body. DNA vaccines are typically administered along with a technique called electroporation. DNA must be translated to mRNA within the cell nucleus before it can subsequently be translated to protein antigens which stimulate an immune response.

As with nucleic acid vaccines, viral vectored vaccines are a newer technology, using harmless viruses to deliver the genetic code of target vaccine antigens to cells of the body, so that they can produce protein antigens to stimulate an immune response.

Viral vectored vaccines are grown in cell lines and can be developed quickly and easily on a large scale. Viral vectored vaccines are significantly cheaper to produce in most cases compared to nucleic acid vaccines and many subunit vaccines. Replicating viral vectors retain the ability to make new viral particles alongside delivering the vaccine antigen when used as a vaccine delivery platform. As with live attenuated whole pathogen vaccines this has the inherent advantage as a replicating virus that it can provide a continuous source of vaccine antigen over an extended period of time compared to non-replicating vaccines, and so is likely to produce a stronger immune response.

A single vaccine may be enough to give protection. Replicating viral vectors are typically selected so that the viruses themselves are harmless, or are attenuated, so whilst they are infecting the host, they cannot cause disease. Despite this, as there is still viral replication going on there is an increased chance of mild adverse events reactions with these vaccines.

Here are 2 exciting examples:. Getting vaccinated is easy. See how vaccines are developed, approved, and monitored. Suite L Washington, D. A-Z Index. Vaccine Types. When scientists create vaccines, they consider: How your immune system responds to the germ Who needs to be vaccinated against the germ The best technology or approach to create the vaccine Based on a number of these factors, scientists decide which type of vaccine they will make.

There are several types of vaccines, including: Inactivated vaccines Live-attenuated vaccines Messenger RNA mRNA vaccines Subunit, recombinant, polysaccharide, and conjugate vaccines Toxoid vaccines Viral vector vaccines Inactivated vaccines Inactivated vaccines use the killed version of the germ that causes a disease. Inactivated vaccines are used to protect against: Hepatitis A Flu shot only Polio shot only Rabies Live-attenuated vaccines Live vaccines use a weakened or attenuated form of the germ that causes a disease.

But live vaccines also have some limitations. These vaccines are used to protect against: Hib Haemophilus influenzae type b disease Hepatitis B HPV Human papillomavirus Whooping cough part of the DTaP combined vaccine Pneumococcal disease Meningococcal disease Shingles Toxoid vaccines Toxoid vaccines use a toxin harmful product made by the germ that causes a disease.

Toxoid vaccines are used to protect against: Diphtheria Tetanus Viral vector vaccines For decades, scientists studied viral vector vaccines. The future of vaccines Did you know that scientists are still working to create new types of vaccines?