Tag Archives: vaccine

Another Great Reason to Get a Flu Shot

Getting an annual flu shot seriously reduces your risk of getting the flu, but now it turns out that it could also help prevent a heart attack:

We included 78,706 patients, of whom 16,012 were cases and 62,694 were matched controls. Influenza vaccination had been received in the previous year by 8,472 cases (52.9%) and 32,081 controls (51.2%) and was associated with a 19% reduction in the rate of acute myocardial infarction.

A little jab'll do ya. Image courtesy US Army Corps of Engineers.

A little jab'll do ya. Image courtesy US Army Corps of Engineers.

The researchers also found that getting the vaccine earlier in the season correlates with a lower rate of heart attacks than getting the vaccine after Thanksgiving. What are you waiting for?

Then Again, Maybe Not

The apparent success of an HIV vaccine trial last year, after years of failures in the field, was a huge surprise to most virologists (including me). Now it looks like the vaccine regimen’s effect may have been only temporary:

An AIDS vaccine that appears to have worked at least partly in Thailand may only temporarily protect patients, with the effects starting to wane after a year or so, researchers reported on Thursday. That may explain why results of the experimental vaccine have been so difficult to interpret, said Dr. Nelson Michael, a colonel at the Walter Reed Army Research Institute of Research in Maryland, who helped lead the trial. Michael’s team is trying to find out how or why it might have worked. They surprised the world last September when they showed the experimental vaccine cut the risk of infection by 31 percent over three years.

That certainly isn’t what anyone wanted to hear, but against the backdrop of HIV vaccine research, it’s not entirely bad news. Even brief, weak protection is better than any previous vaccine has done against this virus, so it still looks like Michael and his colleagues are onto something. Fortunately, they’re now organizing a large follow-up study to analyze blood samples from the vaccinated volunteers. If they can find biological changes that correlate with protection, or “correlates of immunity,” then that could form the basis for a new round of vaccine development. I wish them luck. They’ll need it.

Another Virus in The Vaccination Queue

If vaccine development continues apace, human papilloma virus, and with it cervical cancer, could go the way of smallpox:

Professor Jack Cuzick told Europe’s largest cancer congress, ECCO 15 – ESMO 34 in Berlin … that while the current HPV vaccines protect against two cancer-causing strains of the HPV virus, soon there would be vaccines available that protect against nine types. If vaccination were to be combined with HPV screening which is much more sensitive than the currently used Pap smear test, then eventually the cancer would disappear in those countries that had successfully implemented national programmes. However, this would require political will and effort at both national and European level.

“It’s important to say up front that the HPV is responsible for all cervix cancer,” said Prof Cuzick. “If you can eradicate the virus, the cancer will not appear. So the current vaccine holds the promise of eradicating about 70-75% of cervical cancers caused by HPV types 16 and 18, and there appears to be some additional cross protection amongst types that are closely related to 16 or 18, in particular 31, 45 and a little bit of 33. There are new vaccines being planned that will vaccinate against nine types. If they are successful, there should be no need to screen women that have been vaccinated at all. That’s the long-term future: vaccination and no screening. After about 50 years, we could see cervical cancer disappearing.”

The bit about political will is crucial, of course, as is something that this press release leaves out entirely: developing countries. As I’ve mentioned here once or twice (okay, maybe three or four times), wiping out a virus is a pretty tall order. Still, it’s encouraging to see that cervical cancer could be brought under control, if not eradicated, in the forseeable future.

Polio Vaccination in Nigeria: WHO Just Can’t Win

The BBC is reporting another depressing development in the World Health Organization (WHO) campaign to eradicate polio:

Nigeria is fighting a rare outbreak of a vaccine-derived form of polio, says the UN’s World Health Organization. It says 69 children in the north have caught the paralysing disease from others who had already been immunised. The WHO says such rare outbreaks have occurred where immunisation campaigns did not reach enough of the population.

If you’re just tuning in, Nigeria is the same country that had a disastrous polio vaccine boycott in 2003, spurred by extremists who claimed the vaccine was part of a Western plot to eradicate Muslims. The rumor managed to shut down vaccination campaigns across wide swaths of territory, causing a predictable spike in polio infection rates shortly therafter. Now that there’s an outbreak of vaccine-derived polio, we can be sure the same scare-mongers will be claiming vindication. Would this be happening if we took a more integrated approach to poor countries’ public health problems, rather than focusing our energy and money on ego-driven eradication campaigns against individual diseases?

Still Pulling for Poor Countries’ Vaccines

The G7 nations are apparently setting up another effort to entice drug companies to work on unprofitable diseases:

The UK and other leading industrialised nations are setting up a £750m ($1.5bn) fund to speed up the development of new vaccines for use in poorer countries.

The plan is to subsidise the future purchase of vaccines in the hope this will galvanise drug firms into action.

A vaccine for pneumococcal disease is the first target.

A jab already exists, but developing countries need a tailored version which firms have been slow to invest in as there is no guaranteed market.

This is an example of a “pull” incentive, guaranteeing a market for the putative vaccine by committing rich countries to buy a certain amount once it’s developed. This contrasts with “push” efforts, which fund the research up front. The idea of “pull” systems is that drug companies will invest their own money in development if they perceive that there’s going to be a market for the final product. By guaranteeing an artificial market in the future, we can reap the benefits of corporate research without having to put taxpayers’ cash on the table until the products are ready.

It’s a neat idea, and drug company executives publicly laud it. Privately, however, they consistently admit that their own company probably won’t do it. Developing a new vaccine can take a decade or more, and there’s a tremendous risk that politicians yet to be elected will balk at honoring the expensive promises of their predecessors. Also, the governments involved have to be willing to pay the companies a suitable profit margin beyond their basic development costs, which would inevitably become a political lightning rod.

On the other hand, as the ongoing problems with “push” efforts like the Bioshield project show, there’s clearly a need for some alternative. It’s just not clear that pulling will be any more successful.

A New Twist on Herd Immunity

Catching up on some old but still under-discussed news, here’s an interesting article published on the Proceedings of the National Academy of Sciences Web site a couple of months ago. The researchers’ strategy was to conjugate an antigen from the malaria parasite to a larger protein, then use that as a vaccine. Here’s the twist: the antigen is only expressed in the mosquito stage of the malaria life cycle, so people who get such a vaccine wouldn’t actually be immune from malaria.

So what’s the point? Well, if a vaccinee got malaria, then got bitten by a mosquito, the insect would drink antibodies as well as the parasite. When the parasite tried to continue its life cycle in the mosquito to get to the next host, the antibodies would take it out. In other words, vaccinees could still get the disease, but they wouldn’t pass it on to others. If it works as well in humans as it appears to in monkeys, this could be a very clever way to control one of the world’s deadliest diseases. But are people really altruistic enough to accept a vaccine like that?

Measles vaccine vs. crocodile dung

Just as Nigeria is starting to recover from a disastrous bout of paranoia about polio vaccination, they now have news outlets trumpeting the use of – I couldn’t make this stuff up – crocodile excrement as a treatment for measles. While dispensing this appallingly bad advice, the article even manages to butcher elementary-school biology:

Going down memory lane, Chief Taiwo said the late traditional ruler in the town, Oba Ogundele who brought the amphibian creature to the village nurtured it well before he died.

Apena of Ijaleland, disclosed that Oba Ogundele got the crocodile in a river and started nurturing it adding that the reptile gives healing.

“A measles afflicted person is sure of cure once he gets to this village and draws water from the abode of the crocodile and rub on his or her entire body. I’m not kidding. He or she must receive healing. It sounds strange, but the crocodile has helped many people, both near and far”, Taiwo said.

Got that, kids? Crocodiles are amphibians, and their poop can cure measles. I’m speechless.

Polio Season, Again

For the first half of the 20th century, every summer was polio season. Poliovirus, which spreads by the infamous “fecal-oral route,” thrives in sewage systems and contaminated waterways all year, but summer offers many more chances for exposure. Anyone swimming at a local beach or public pool routinely contracted it.

Most people who catch poliovirus develop nothing more serious than a mild diarrhea, but about one to two percent of them progress to the neurological disease that made polio one of the most feared infectious agents in the world. One or two percent doesn’t sound like much, but once the virus reaches a watershed, it can infect nearly everyone in the area, so that tiny percentage translates to a huge number of permanently paralyzed children, some of whom even die of the disease.

Polio Pointers for Parents, 1951

The Salk and Sabin polio vaccines brought an end to this era, and references to polio in modern times usually conjure images of iron lungs and FDR. Unfortunately, polio isn’t quite a thing of the past yet, and a misguided, drawn-out campaign by the World Health Organization to eradicate the disease may actually do more harm than good.

Many virologists – including me – have written detailed technical critiques of the WHO’s campaign, none of which have been adequately answered. At this point, the WHO effort seems to be sustained more by egos than sound public health planning. There are numerous flaws in their approach, and while my thesis advisor and I were the first to make a major public statement criticizing it, we were not the first to forsee these difficulties, nor the last to broadcast a warning.

This is one of those cases where it hurts to be right: we’re now seeing the tragic consequences we predicted a decade ago, and once again it’s polio season. Namibia kicked it off this year, with a major outbreak that ended ten polio-free years for that country. The authorities reacted quickly, with a mass immunization drive that sought to catch up with all the people who’d missed being vaccinated before. Since then, we have no more word on outbreaks from Namibia, but the disease also struck Afghanistan this year, and the prospects for organizing a major vaccination campaign in that devastated country are next to nil.

Both the Namibia and Afghanistan outbreaks highlight one of the problems we all saw coming: once the WHO finishes “eradicating” the disease in a country, they essentially turn off the lights and leave. Of course, that’s not the way they describe it, but that’s the net result. Local public health authorities in poor countries, generally overwhelmed by the triple tragedies of AIDS, malaria, and TB, and lacking any coherent backing from their own governments, cannot be expected to keep up with polio vaccination and surveillance. Predictably, vaccination rates decline, the disease gets reintroduced from nearby areas where it’s endemic, and an outbreak starts.

A more insidious problem – also predicted a decade ago – is the rise of vaccine-derived outbreaks. Indeed, several countries, most recently China, have seen sudden outbreaks of polio that actually came from the vaccine. That’s because the Sabin vaccine, which forms the backbone of the WHO eradication effort, produces virulent revertant viruses at a low but nonzero rate. In fact, there’s good evidence that people with compromised immune systems can continue to shed live, virulent poliovirus revertants for years after immunization with the Sabin vaccine. With a sizable portion of the world’s population suffering from immunodeficiency caused by AIDS, that adds up to a lot of chronic virus secreters.

That isn’t a big problem if vaccination rates are high, because the secreted, virulent virus won’t find enough susceptible hosts to spark an outbreak. However, once the WHO declares a country “polio-free,” the political will to continue expensive and unpopular vaccination drives evaporates. Vaccination goes out of fashion, surveillance lapses, and initially there are no consequences. After a few years, though, the number of susceptible hosts builds up high enough, and a vaccine-derived outbreak occurs.

What’s the solution? Stop trying to eradicate diseases and focus on controlling them instead. Even the eradication of smallpox, our only such victory, turned out to be a mixed blessing; if smallpox had faded more gradually, we might have continued developing safer vaccines, and we wouldn’t now be spending quite as many billions of dollars on a mushrooming “biodefense” industry to protect us from bioterrorism. Shifting from polio eradication to polio control would let us integrate this vaccine into a complete package of public health programs, and reinforce the lesson that public health isn’t something you do once and then forget about. We need to help poor countries build comprehensive long-term plans, rather than vast patchworks of Band-Aids.

Unfortunately, that kind of patient planning is done by big groups of people over long periods of time, and it isn’t a great way to advance an individual career. Instead, the folks leading the current WHO effort continue their eradication campaign, and outbreaks continue to strike. We’ll see how it goes next polio season.