Drug delivery
Vaxart’s oral vaccine has fared well in tests, even showing advantages over the standard Covid-19 jab.
Findings from Vaxart’s preclinical studies, including a study published by Duke University last autumn, suggest that its Covid-19 vaccine may inhibit the airborne transfer of the virus better than an injected protein vaccine. “Because the nose is the first line of defence for respiratory pathogens,” Tucker explains, “we think there is a benefit in preventing infection by using our oral vaccine. Plus, the antibodies in the nose (IgA) tend to be more cross-reactive than the antibodies made by injected vaccines (IgG), so we believe we will show an improved ability to block the new variants of concern. Injected vaccines don’t really induce immune responses in the nose.”
“How do you prove you took the vaccine without a band-aid on your arm and a professional certifying that they gave you a jab?”
Dr Sean Tucker 61.6%
The percentage of the world’s
population that has received at least one dose of the vaccine. This figure drops to 10.6% of people in low- income countries.
Our World in Data 12
It may be too soon to compare the efficacy of the two vaccine methods, but there is little doubt that a pill would have a number of clear strategic advantages, including the speed of administration, the lack of cold chain requirements, and the removal of a qualified healthcare professional to administer a jab. “In terms of manufacturing,” Tucker says, “the end step (tableting) is a lot easier than the sterile fill and finish of vials or needles. All of these advantages should translate to lower costs to get vaccines to people.” What is more, “a pill vaccine that is room temperature stable has global implications, particularly in the Southern Hemisphere and other parts of the world, where they don’t have the cold chain or healthcare infrastructures they need to support injections.”
Keep record
The advantages are obvious – so what might be the disadvantages? And, more importantly, what exactly are the chemical and biological barriers to
vaccinating with an oral drug? Echoing Majeed, Tucker comments on the difficulties caused by “the low pH of the stomach. That destroys a lot of proteins and large biologicals like viruses. Some of the biological barriers [also] include immune recognition in the intestine. The intestine’s primary function is to intake food and turn it into energy, not to mount an immune response.” But he is confident that Vaxart has found ways around these problems. “We solved the low pH problem by putting an enteric coating on our vaccine tablets [which] stays intact at low pH solution [thus protecting the contents from acid] and then falls apart at neutral pH, allowing the vaccine to come in contact with intestinal cells,” he says. “We solved the immune recognition problem by co-expressing a double- stranded RNA adjuvant with our protein target. This dsRNA tells the immune system to pay attention, create an immune response and develop memory so you’ll be protected if you ever ‘see’ the protein again.”
Then, there are potential issues around the traceability of an oral vaccine. “There is a concern,” as Majeed notes, “that people might be given an oral vaccine to take later but not actually use it (as sometimes happens with medication for other medical conditions).” Even if people did take it, “how do you prove you took the vaccine without a band-aid on your arm and a professional certifying that they gave you a jab?” Tucker asks. “There are technologies out there that could be used, but it’s not as simple.”
McManus, however, is confident that proof of vaccination should not pose a problem. “Every child in the UK has a vaccine record, and [one of] the vaccines that they get is oral [rotavirus],” he points out, “so why should it be any different [with a Covid-19 vaccine]? It’s a healthcare intervention so you’d keep a record of it.” If we can get oral vaccines made and approved, then healthcare systems in the most developed countries like the UK and the US should be sufficiently capable of keeping track of them through barcodes, safe chain custody, biological standards and detailed patient records. Unfortunately, it does not look like we will get an oral vaccine anytime soon. Tucker optimistically estimates that Vaxart “could be in a position to request emergency use authorisation in about a year”, but even he has to admit that “this depends on what’s happening with new variants and outbreaks”. Yet, if our lives are going to be marked out by biannual Covid-19 vaccine boosters, then the development of a pill seems like an important step, not only for those with trypanophobia, not only for neurodiverse groups, and not only for children, but for all of us. An oral solution may not be the magic pill that solves the vaccine question, but it will certainly sugarcoat it. ●
World Pharmaceutical Frontiers /
www.worldpharmaceuticals.net
Vaxart
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53
