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Showing posts with label vaccine. Show all posts
Showing posts with label vaccine. Show all posts

Snapdate: Ebola virus diseaseClick on image to enlarge.

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This is one of the data visualizations from my Ebola virus disease (EVD) graphs and tallies page.[1]

A crude extrapolation from current publicly available Ebola virus disease (EVD) confirmed case numbers. To see how I made this please visit here.[2]
The P-value for this linear trend model is <0.0001. 
The standard error = 6.13; R-squared = 0.20.
Click on graph to enlarge.
The first time I posted it I wondered if the end was in sight. That was 6th of May. Over three months later I'm wondering that again - but this time things are a bit different. There has been a steady decline in new cases, also in cases that cannot be tracked back to a known source and in cases found only after they have died of EVD. There have also been the first very promising results from one of the vaccine candidates in Guinea [4] - which has always been a difficult locale for the control of EVD case activity.

So it does look much more likely that the end to EVD in West Africa, or at least an end, is nigh.

By "an end" I mean that we may be close to seeing the cessation of new cases popping up in transmission chains each and every week. We may soon be seeing zero new cases for long periods of time. Those blissful stretches however, may be punctuated by a case arising from parts unknown. They may be tracked to a sexual transmission event, or their origin may never be fully understood. We saw this scenario in Liberia.[3] Virus characterisation indicated that the Ebola virus variant from the young Liberian man was most closely resembled other viruses that had been circulating in Liberia weeks before; the exact source of his infection though, remains unknown.

So we're not at all free and clear of this virus yet - but we are getting very close to shifting into another phase. It's still a long haul with many weeks of anxious waiting and heightened vigilance as well as the need to retain the capacity to cope with a new case or cases. But that said, we do seem to have taken one more step back from the precipice we once stared into as we imagined an Africa fending off a rolling EVD epidemic - and a world at risk as well - however unlikely that should have been. 

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H7N9 vaccine progresses through Phase I trials...

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Back in August I wrote about Novavax entering Phase I clinical trials with its virus-like particle vaccine (VLP) to prevent influenza A(H7N9) virus disease. It is based on the A/Anhui/1/2013 strain.

Novavax, A United States company, has now reported in the New England Journal of Medicine that 80% of people may be protected by the generation of anti-H7N9 antibodies in response to 2x 5�g injections in the presence of 60 units of CSL's Iscomatrix adjuvant (see more on adjuvants in my August piece). 284 people were enrolled in a trial in Australia to determine these "very preliminary" results. Increased reactions were seen among the immunized at the injection site, but few were severe.

The move away from the egg-based vaccine manufacturing system is likely to allow vaccines to be produced in much shorter periods; 12-weeks after an outbreak starts, with 50,000,000 doses potentially available in 4-months.

You may ask, why then is it precisely 9-months after the 1st H7N9 case was retrospectively identified, and Novavax is still only at Phase I trials? I think, and I'm no expert in this area, that the process will increase in speed once the 'backbone' (the VLPs being used here which are based on a baculovirus, all produced in insect cells) in combination with this adjuvant etc, have been through the entire clinical trial process the first time. A successful backbone can be leveraged for other vaccines too.

You can see a little more of the process of making the VLPs, in this case for respiratory syncytial virus, here.

So, big changes lie not-too-far ahead for influenza vaccines....assuming the course through clicnial trials is smooth sailing of course!

For those hypersensitive to hyperlinks...
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Influenza A(H7N9) vaccine approved by Chinese food and drug administration for use...[UPDATED]

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CNTV English language newshour reports that the home-made first influenza vaccine from China has met local safety standards and is ready for mass production. The vaccine was a collaborative development between the First Affiliated Hospital under the School of Medicine of Zhejiang University, Hong Kong University, Chinese Center for Disease Control and Prevention, National Institute for Food and Drug Control, and Chinese Academy of Medical Sciences.

It will be interesting to read about what the virus is comprised of (seems to use the older influenza PR8 strain as a backbone, employing a reverse genetics approach to add in H7N9) and how the vaccine makers got around H7N9's predicted low immunogenicity issue, what the dosing regimen is and what was used as adjuvant (mentioned here, earlier). As Mike Coston notes on Avian Flu Diary, the announcements don't detail much of the preceding safety trials that should have been carried out for a vaccine to have reached this level of development. 

Mike has an earlier post over on Avian Flu Diary that reminds us about the few that are sick enough to be obviously ill....and perhaps the many that do not seek medical attention because infection resulted in relatively mild disease. Largely, as Mike notes, any numbers assigned to infections that result in milder or even asymptomatic disease are guesstimates for now - at least until some actual testing is reported. History supports that mild infections are likely, but every zoonosis is its own beast.

More coming soon on the vaccine's development path and on testing to understand H7N9's reach.

Thanks to @makoto_au_japon for identifying the vaccine story through Twitter

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A scientist who knows how to communicate - and isn't bad with the vaccines either

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Kim Stephens has written a nice piece in my local 'paper', brisbanetimes.com.au, on Prof Ian Frazer's latest vaccine achievement. 

You may know Prof Frazer from such things as...the anticancer human papillomavirus (HPV) vaccine, a safe, highly effective but underutilized (in some parts at least) vaccine recommended for kids aged 11 or 12.

Anyone who can make immunological concepts sound as simple as Prof Frazer does in this latest interview should get an award....wait..he already has a couple.

Prof Frazer's latest, globally important achievement, is the human trialing of a herpes simplex virus 2 (HSV-2) vaccine. This is to defend against the virus that most notably gives you genital blisters. A virus down under, you might say. Or you might not.

But the vaccine is not just defensive, apart from preventing disease  it also therapeutic - it can treat the infection you already have. 

Skin cancer is next in case you're keeping tabs.

Thanks to Katherine Arden for alerting me to this story.
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H7N9 vaccine update...[UPDATED]

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Hat tip to Dr. Nicholas Kelly for JAMA link reminder.

Earlier in the month, Zou Yong, quality directer of China based Sinovac Biotech Ltd  the Chinese Center for Disease Control and Prevention, noted that preliminary work on an adjuvanted (see bwlow) H7N9 vaccines was complete and are ready for safety  stability and clinical trials. It has already completed been through animal testing and the vaccine seems to work in our furry little friends.

In July, Novavax commenced Phase I clinical trials in adults of its adjuvanted virus-like particle (VLP) H7N9 vaccine. This trial assesses vaccine safety and immunogenicity (ability to make the recipient mount a useful immune response to the virus - A/Anhui/1/2013 (H7N9))

Helen Branswell (listed as one of Wired's best sources of infectious diseases info), writing at the Vancouver Sun, notes that 4 companies, have or will be conducting trials on H7N9 vaccines - all up costing the guy footing the bill, the US government, $1oo-million. Sanofi Pasteur, Novartis and MedImmune (using live, weakened ["attentuated"] H7N9 virus) also have products in near clicnial trial stages while GSK, CSL, Protein Sciences and Vaccinate are catching up.

As I've written before, H7N9 is a stealth virus in humans as well as chickens. In the latter instance - stealth refers to producing little disease in chickens while in the former, stealthiness is to do with problems in creating a vaccine based on H7N9 that will trigger a suitably effective immune response to what is a relatively weak trigger of human immunity.

But Branswell notes, there remains the need to define the best adjuvant (a vaccine additive "booster" that allows the manufacturer to use the minimum amount of antigen [the virus bit] while still obtaining the best immune reaction to it) however Sinovac has shown that with one, the vaccine works better than was previously expected. Its not unexpected that avian influenza viruses to need help to trigger a good immune response for a human host according to Dr. John Treanor's comments in the article.

The impact of using an adjuvant is known as "antigen sparing". The makers would like to spread the viral antigen out as far as possible to make the greatest number of doses from what they have, as quickly as possible so adjuvants are very important...and a science unto themselves.

So, a lot of work for H7N9. As Osterholm, Ballering and Kelley wrote back in May, for any pandemic vaccine to be of benefit, development time needs to be small while production scale and distribution capacity need to be big. And don't forget, the companies with the big vaccine production capacity still make our seasonal influenza vaccines too - and its no mean feat to switch off production of one product and switch on another. New vaccine technologies are required, and are being developed. Once a vaccine platform has had a successful clicnial trail path, it should be easier to leverage that as the basis for similar vaccines protecting from different viruses/viral strains, in the future.

For influenza A(H1N1)pdm09 virus, a vaccine arrived nearly 2-months after the season wave of infections had crested. Thankfully  H7N9 has not managed the adaptations required for rapid and efficient human-to-human spread.

While a licensed, killed influenza A(H5N1) virus vaccine was prepared some time back, I'm not sure about their current capacity to scale up (shelf lives being what they are)  if H5N1 is the influenza to jump to pandemic status rather than H7N9. If either do.
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Delay to extension of Hendra virus vaccine period...it's not a ferret's life!

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Based on ABC News, Yahoo News

Who'd wanna be a ferret? 

They are great for growing influenza viruses and testing their ability to transmit between animals as a model for human-to-human transmission. Ferrets are apparently also useful for hosting Hendra virus (HeV) replication. 

Because ferrets are cheaper and easier to test vaccines on than horses, they are used as negative control animals for HeV vaccine studies like the one by Dr Deborah Middleton, veterinary pathologist at Australian Animal Health Laboratory (AAHL), Commonwealth Scientific and Industrial Research Organisation (CSIRO) was conducting (the vaccine was created and developed by CSIRO and Pfizer). 

This study was aiming to confirm that the current Hendra vaccine booster could be given every 12-months, rather than every 6-months, as it currently is. This would be a saving of ~$100/horse/year.

UPDATE: Thanks to Shane Granger, @gmggranger for more realistic costings which equate to $165/horse + microchipping at the first visit (if not already done) or some savings for more than 1 horse: 


Unfortunately, the study failed because the unvaccinated ferret control group did not become ill after being infected. This means the experiment couldn't show that the vaccine was protecting against the virus upon challenge. 

The problem was traced to a bad vial of HeV. The lab virus used to infect the animals was not as potent as expected of a real life, or "wild",  infection of horses.

Vaccination of horses is encouraged by Biosecurity Queensland to fend off the virus is lethal in viruses, in about half of human who come into close contact with infected animals and can infect dogs also as seen recently at an infected property in New South Wales and in August 2011 on a property in Queensland.

This year (2013), the Royal National Agricultural and Industrial Association of Queensland (RNA) has mandated that all horses attending or competing at its Royal Queensland Show (Ekka, held in Brisbane, Queensland) should be vaccinated for HeV. 
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H7N9: the stealth bomber virus.

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As described by EpiVax Inc. previously and now described in a scientific paper in Human Vaccine and Immunotherapeutics, the H7N9 virus is not just stealthy in poultry, its also hard to find in humans. There is concern over whether it will be possible to produce a vaccine that will be effective against a virus with such low predicted immunogenic potential. 

An H7N9 vaccine, without the right concoction of boosting additives, is predicted to be a poor trigger of our immune system's response to it. This is because H7N9 doesn't have as many T cell epitopes as other flu viruses...these are the bits recognized by important white blood cells that fight infection and shorten disease. Because of this human 'stealth' capability, it may evade the human response. 

This has obvious implications for disease (more severe if the host cannot shut the virus down quickly) and may also have implications for the usefulness of existing serodiagnostic (virus-specific antibody-detecting) assays.
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