I know you didn't ask me, but Xolair is an anti-idiotypic antibody:

http://www.merriam-webster.com/dictionary/anti-idiotypic

an antibody that binds to the antigen-combining site of another antibody either suppressing or enhancing the immune response

In other words, IgE is a type of antibody (immunoglobulin) -- i.e., a protein -- and Xolair is an antibody that binds to IgE.

As explained in Wikipedia,

http://en.wikipedia.org/wiki/Omalizumab

Omalizumab [Xolair] inhibits the binding of IgE to the high-affinity IgE receptor FcεRI by binding to an epitope (a conformational area) on IgE that overlaps with the site to which FcεRI binds. . . . . 

Reduction in surface bound IgE on FcεRI-bearing cells limits the degree of release of mediators of the allergic response.

http://en.wikipedia.org/wiki/Fc%CE%B5RI

FcεRI is found on epidermal Langerhans cells, eosinophils, mast cells and basophils.^[2][3] As a result of its cellular distribution, this receptor plays a major role in controlling allergic responses. FcεRI is also expressed on antigen-presenting cells, and controls the production of important immune mediators called cytokines that promote inflammation.^[4]

Indeed, Xolair has "off-label" uses: 

http://asthma.emedtv.com/xolair/xolair-uses.html

Although Xolair has been approved to treat allergic asthma, the medication can also be used "off-label" to treat other conditions. Off-label Xolair uses can include the prevention of severe food allergies or other types of allergies (such as seasonal allergies). Xolair is not a cure or treatment for asthma, but it can help to prevent asthma attacks from occurring. The medication has been approved for use in people who are at least 12 years old.

In contrast, the DNA vaccine described in the Telegraph article is just that:  a DNA vaccine, and not a protein (as is Xolair). 

As explained in Wikipedia, DNA vaccines are third generation vaccines: 

http://en.wikipedia.org/wiki/DNA_vaccination

First generation vaccines are whole-organism vaccines – either live and weakened, or killed forms.^[2] Live, attenuated vaccines, such as smallpox and polio vaccines, are able to induce killer T-cell (T_C or CTL) responses, helper T-cell (T_H) responses and antibody immunity. However, there is a small risk that attenuated forms of a pathogen can revert to a dangerous form, and may still be able to cause disease in immunocompromised people (such as those with AIDS). While killed vaccines do not have this risk, they cannot generate specific killer T cell responses, and may not work at all for some diseases.^[2] In order to minimise these risks, so-called second generation vaccines were developed. These are subunit vaccines, consisting of defined protein antigens (such as tetanus or diphtheria toxoid) or recombinant protein components (such as the hepatitis B surface antigen). These, too, are able to generate T_H and antibody responses, but not killer T cell responses.

 

DNA vaccines are third generation vaccines, and are made up of a small, circular piece of bacterial DNA (called a plasmid) that has been genetically engineered to produce one or two specific proteins (antigens) from a pathogen. The vaccine DNA is injected into the cells of the body, where the "inner machinery" of the host cells "reads" the DNA and converts it into pathogenic proteins. Because these proteins are recognised as foreign, when they are processed by the host cells and displayed on their surface, the immune system is alerted, which then triggers a range of immune responses.^[1][2] These DNA vaccines developed from “failed” gene therapy experiments. The first demonstration of a plasmid-induced immune response was when mice inoculated with a plasmid expressing human growth hormone elicited antibodies instead of altering growth.^[3]

According to the Telegraph article, the vaccine is comprised of: 

http://www.telegraph.co.uk/health/healthnews/7845325/One-size-fits-all-allergy-jab-for-hay-fever-asthma-and-eczema-on-the-way.html

. . . .pieces of synthetic DNA similar to those found in the bug that causes tuberculosis or TB.

The DNA fools the body into thinking it is under attack from a dangerous bug, kick-starting a multi-pronged immune response.

Now, just how the vaccine accomplishes this feat, and how in the process it reduces asthma attacks and symptoms, and allergy symptoms, I don't know, and it may, in fact, be a trade secret at this point.  Nonetheless, the mechanism of action is obviously different from that of Xolair (if that's what your question was).